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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-03-26 04:42:12 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2016-03-26 05:27:59 -0300
commita156245300d5362a3b4c4afdace9e2b90169fe43 (patch)
tree392741d5ee3e05bc089c7af2db884b99899217d7 /mm
parent03dd4cb26d967f9588437b0fc9cc0e8353322bb7 (diff)
Remove UKSM support since the latest patch is very unstable and obsolete for the 4.5-gnu kernel version
Diffstat (limited to 'mm')
-rw-r--r--mm/Kconfig26
-rw-r--r--mm/Makefile3
-rw-r--r--mm/memory.c36
-rw-r--r--mm/mmap.c44
-rw-r--r--mm/rmap.c4
-rw-r--r--mm/uksm.c5525
-rw-r--r--mm/vmstat.c3
7 files changed, 7 insertions, 5634 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index 1b1b681c9..03cbfa072 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -322,32 +322,6 @@ config KSM
See Documentation/vm/ksm.txt for more information: KSM is inactive
until a program has madvised that an area is MADV_MERGEABLE, and
root has set /sys/kernel/mm/ksm/run to 1 (if CONFIG_SYSFS is set).
-choice
- prompt "Choose UKSM/KSM strategy"
- default UKSM
- depends on KSM
- help
- This option allows to select a UKSM/KSM stragety.
-
-config UKSM
- bool "Ultra-KSM for page merging"
- depends on KSM
- help
- UKSM is inspired by the Linux kernel project \u2014 KSM(Kernel Same
- page Merging), but with a fundamentally rewritten core algorithm. With
- an advanced algorithm, UKSM now can transparently scans all anonymously
- mapped user space applications with an significantly improved scan speed
- and CPU efficiency. Since KVM is friendly to KSM, KVM can also benefit from
- UKSM. Now UKSM has its first stable release and first real world enterprise user.
- For more information, please goto its project page.
- (www.kerneldedup.org)
-
-config KSM_LEGACY
- bool "Legacy KSM implementation"
- depends on KSM
- help
- The legacy KSM implementation from Redhat.
-endchoice
config DEFAULT_MMAP_MIN_ADDR
int "Low address space to protect from user allocation"
diff --git a/mm/Makefile b/mm/Makefile
index 90fd58a58..2ed43191f 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -47,8 +47,7 @@ obj-$(CONFIG_SPARSEMEM) += sparse.o
obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o
obj-$(CONFIG_SLOB) += slob.o
obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o
-obj-$(CONFIG_KSM_LEGACY) += ksm.o
-obj-$(CONFIG_UKSM) += uksm.o
+obj-$(CONFIG_KSM) += ksm.o
obj-$(CONFIG_PAGE_POISONING) += debug-pagealloc.o
obj-$(CONFIG_SLAB) += slab.o
obj-$(CONFIG_SLUB) += slub.o
diff --git a/mm/memory.c b/mm/memory.c
index 09e967a3c..8132787ae 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -122,28 +122,6 @@ unsigned long highest_memmap_pfn __read_mostly;
EXPORT_SYMBOL(zero_pfn);
-#ifdef CONFIG_UKSM
-unsigned long uksm_zero_pfn __read_mostly;
-EXPORT_SYMBOL_GPL(uksm_zero_pfn);
-struct page *empty_uksm_zero_page;
-
-static int __init setup_uksm_zero_page(void)
-{
- unsigned long addr;
- addr = __get_free_pages(GFP_KERNEL | __GFP_ZERO, 0);
- if (!addr)
- panic("Oh boy, that early out of memory?");
-
- empty_uksm_zero_page = virt_to_page((void *) addr);
- SetPageReserved(empty_uksm_zero_page);
-
- uksm_zero_pfn = page_to_pfn(empty_uksm_zero_page);
-
- return 0;
-}
-core_initcall(setup_uksm_zero_page);
-#endif
-
/*
* CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
*/
@@ -155,7 +133,6 @@ static int __init init_zero_pfn(void)
core_initcall(init_zero_pfn);
-
#if defined(SPLIT_RSS_COUNTING)
void sync_mm_rss(struct mm_struct *mm)
@@ -890,11 +867,6 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
get_page(page);
page_dup_rmap(page, false);
rss[mm_counter(page)]++;
-
- /* Should return NULL in vm_normal_page() */
- uksm_bugon_zeropage(pte);
- } else {
- uksm_map_zero_page(pte);
}
out_set_pte:
@@ -1129,7 +1101,6 @@ again:
tlb->fullmm);
tlb_remove_tlb_entry(tlb, pte, addr);
if (unlikely(!page))
- uksm_unmap_zero_page(ptent);
continue;
if (!PageAnon(page)) {
@@ -1966,10 +1937,8 @@ static inline void cow_user_page(struct page *dst, struct page *src, unsigned lo
clear_page(kaddr);
kunmap_atomic(kaddr);
flush_dcache_page(dst);
- } else {
+ } else
copy_user_highpage(dst, src, va, vma);
- uksm_cow_page(vma, src);
- }
}
static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
@@ -2114,7 +2083,6 @@ static int wp_page_copy(struct mm_struct *mm, struct vm_area_struct *vma,
new_page = alloc_zeroed_user_highpage_movable(vma, address);
if (!new_page)
goto oom;
- uksm_cow_pte(vma, orig_pte);
} else {
new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
if (!new_page)
@@ -2140,9 +2108,7 @@ static int wp_page_copy(struct mm_struct *mm, struct vm_area_struct *vma,
mm_counter_file(old_page));
inc_mm_counter_fast(mm, MM_ANONPAGES);
}
- uksm_bugon_zeropage(orig_pte);
} else {
- uksm_unmap_zero_page(orig_pte);
inc_mm_counter_fast(mm, MM_ANONPAGES);
}
flush_cache_page(vma, address, pte_pfn(orig_pte));
diff --git a/mm/mmap.c b/mm/mmap.c
index be5ee9f7f..76d1ec291 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -43,7 +43,6 @@
#include <linux/printk.h>
#include <linux/userfaultfd_k.h>
#include <linux/moduleparam.h>
-#include <linux/ksm.h>
#include <asm/uaccess.h>
#include <asm/cacheflush.h>
@@ -293,7 +292,6 @@ static struct vm_area_struct *remove_vma(struct vm_area_struct *vma)
if (vma->vm_file)
fput(vma->vm_file);
mpol_put(vma_policy(vma));
- uksm_remove_vma(vma);
kmem_cache_free(vm_area_cachep, vma);
return next;
}
@@ -758,16 +756,9 @@ int vma_adjust(struct vm_area_struct *vma, unsigned long start,
long adjust_next = 0;
int remove_next = 0;
-/*
- * to avoid deadlock, ksm_remove_vma must be done before any spin_lock is
- * acquired
- */
- uksm_remove_vma(vma);
-
if (next && !insert) {
struct vm_area_struct *exporter = NULL;
- uksm_remove_vma(next);
if (end >= next->vm_end) {
/*
* vma expands, overlapping all the next, and
@@ -861,7 +852,6 @@ again: remove_next = 1 + (end > next->vm_end);
end_changed = true;
}
vma->vm_pgoff = pgoff;
-
if (adjust_next) {
next->vm_start += adjust_next << PAGE_SHIFT;
next->vm_pgoff += adjust_next;
@@ -932,22 +922,16 @@ again: remove_next = 1 + (end > next->vm_end);
* up the code too much to do both in one go.
*/
next = vma->vm_next;
- if (remove_next == 2) {
- uksm_remove_vma(next);
+ if (remove_next == 2)
goto again;
- } else if (next) {
+ else if (next)
vma_gap_update(next);
- } else {
+ else
mm->highest_vm_end = end;
- }
- } else {
- if (next && !insert)
- uksm_vma_add_new(next);
}
if (insert && file)
uprobe_mmap(insert);
- uksm_vma_add_new(vma);
validate_mm(mm);
return 0;
@@ -1332,9 +1316,6 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
vm_flags |= calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) |
mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
- /* If uksm is enabled, we add VM_MERGABLE to new VMAs. */
- uksm_vm_flags_mod(&vm_flags);
-
if (flags & MAP_LOCKED)
if (!can_do_mlock())
return -EPERM;
@@ -1673,7 +1654,6 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
allow_write_access(file);
}
file = vma->vm_file;
- uksm_vma_add_new(vma);
out:
perf_event_mmap(vma);
@@ -1715,7 +1695,6 @@ allow_write_and_free_vma:
if (vm_flags & VM_DENYWRITE)
allow_write_access(file);
free_vma:
- uksm_remove_vma(vma);
kmem_cache_free(vm_area_cachep, vma);
unacct_error:
if (charged)
@@ -2511,8 +2490,6 @@ static int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
else
err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new);
- uksm_vma_add_new(new);
-
/* Success. */
if (!err)
return 0;
@@ -2773,7 +2750,6 @@ static unsigned long do_brk(unsigned long addr, unsigned long len)
return addr;
flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
- uksm_vm_flags_mod(&flags);
error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
if (offset_in_page(error))
@@ -2831,7 +2807,6 @@ static unsigned long do_brk(unsigned long addr, unsigned long len)
vma->vm_flags = flags;
vma->vm_page_prot = vm_get_page_prot(flags);
vma_link(mm, vma, prev, rb_link, rb_parent);
- uksm_vma_add_new(vma);
out:
perf_event_mmap(vma);
mm->total_vm += len >> PAGE_SHIFT;
@@ -2868,12 +2843,6 @@ void exit_mmap(struct mm_struct *mm)
/* mm's last user has gone, and its about to be pulled down */
mmu_notifier_release(mm);
- /*
- * Taking write lock on mmap_sem does not harm others,
- * but it's crucial for uksm to avoid races.
- */
- down_write(&mm->mmap_sem);
-
if (mm->locked_vm) {
vma = mm->mmap;
while (vma) {
@@ -2909,11 +2878,6 @@ void exit_mmap(struct mm_struct *mm)
vma = remove_vma(vma);
}
vm_unacct_memory(nr_accounted);
-
- mm->mmap = NULL;
- mm->mm_rb = RB_ROOT;
- vmacache_invalidate(mm);
- up_write(&mm->mmap_sem);
}
/* Insert vm structure into process list sorted by address
@@ -3023,7 +2987,6 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
new_vma->vm_ops->open(new_vma);
vma_link(mm, new_vma, prev, rb_link, rb_parent);
*need_rmap_locks = false;
- uksm_vma_add_new(new_vma);
}
return new_vma;
@@ -3153,7 +3116,6 @@ static struct vm_area_struct *__install_special_mapping(
vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
perf_event_mmap(vma);
- uksm_vma_add_new(vma);
return vma;
diff --git a/mm/rmap.c b/mm/rmap.c
index ea35ca339..79f3bf047 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1125,9 +1125,9 @@ void page_move_anon_rmap(struct page *page,
/**
* __page_set_anon_rmap - set up new anonymous rmap
- * @page: Page to add to rmap
+ * @page: Page to add to rmap
* @vma: VM area to add page to.
- * @address: User virtual address of the mapping
+ * @address: User virtual address of the mapping
* @exclusive: the page is exclusively owned by the current process
*/
static void __page_set_anon_rmap(struct page *page,
diff --git a/mm/uksm.c b/mm/uksm.c
deleted file mode 100644
index 2ce796323..000000000
--- a/mm/uksm.c
+++ /dev/null
@@ -1,5525 +0,0 @@
-/*
- * Ultra KSM. Copyright (C) 2011-2012 Nai Xia
- *
- * This is an improvement upon KSM. Some basic data structures and routines
- * are borrowed from ksm.c .
- *
- * Its new features:
- * 1. Full system scan:
- * It automatically scans all user processes' anonymous VMAs. Kernel-user
- * interaction to submit a memory area to KSM is no longer needed.
- *
- * 2. Rich area detection:
- * It automatically detects rich areas containing abundant duplicated
- * pages based. Rich areas are given a full scan speed. Poor areas are
- * sampled at a reasonable speed with very low CPU consumption.
- *
- * 3. Ultra Per-page scan speed improvement:
- * A new hash algorithm is proposed. As a result, on a machine with
- * Core(TM)2 Quad Q9300 CPU in 32-bit mode and 800MHZ DDR2 main memory, it
- * can scan memory areas that does not contain duplicated pages at speed of
- * 627MB/sec ~ 2445MB/sec and can merge duplicated areas at speed of
- * 477MB/sec ~ 923MB/sec.
- *
- * 4. Thrashing area avoidance:
- * Thrashing area(an VMA that has frequent Ksm page break-out) can be
- * filtered out. My benchmark shows it's more efficient than KSM's per-page
- * hash value based volatile page detection.
- *
- *
- * 5. Misc changes upon KSM:
- * * It has a fully x86-opitmized memcmp dedicated for 4-byte-aligned page
- * comparison. It's much faster than default C version on x86.
- * * rmap_item now has an struct *page member to loosely cache a
- * address-->page mapping, which reduces too much time-costly
- * follow_page().
- * * The VMA creation/exit procedures are hooked to let the Ultra KSM know.
- * * try_to_merge_two_pages() now can revert a pte if it fails. No break_
- * ksm is needed for this case.
- *
- * 6. Full Zero Page consideration(contributed by Figo Zhang)
- * Now uksmd consider full zero pages as special pages and merge them to an
- * special unswappable uksm zero page.
- */
-
-#include <linux/errno.h>
-#include <linux/mm.h>
-#include <linux/fs.h>
-#include <linux/mman.h>
-#include <linux/sched.h>
-#include <linux/rwsem.h>
-#include <linux/pagemap.h>
-#include <linux/rmap.h>
-#include <linux/spinlock.h>
-#include <linux/jhash.h>
-#include <linux/delay.h>
-#include <linux/kthread.h>
-#include <linux/wait.h>
-#include <linux/slab.h>
-#include <linux/rbtree.h>
-#include <linux/memory.h>
-#include <linux/mmu_notifier.h>
-#include <linux/swap.h>
-#include <linux/ksm.h>
-#include <linux/crypto.h>
-#include <linux/scatterlist.h>
-#include <crypto/hash.h>
-#include <linux/random.h>
-#include <linux/math64.h>
-#include <linux/gcd.h>
-#include <linux/freezer.h>
-#include <linux/sradix-tree.h>
-
-#include <asm/tlbflush.h>
-#include "internal.h"
-
-#ifdef CONFIG_X86
-#undef memcmp
-
-#ifdef CONFIG_X86_32
-#define memcmp memcmpx86_32
-/*
- * Compare 4-byte-aligned address s1 and s2, with length n
- */
-int memcmpx86_32(void *s1, void *s2, size_t n)
-{
- size_t num = n / 4;
- register int res;
-
- __asm__ __volatile__
- (
- "testl %3,%3\n\t"
- "repe; cmpsd\n\t"
- "je 1f\n\t"
- "sbbl %0,%0\n\t"
- "orl $1,%0\n"
- "1:"
- : "=&a" (res), "+&S" (s1), "+&D" (s2), "+&c" (num)
- : "0" (0)
- : "cc");
-
- return res;
-}
-
-/*
- * Check the page is all zero ?
- */
-static int is_full_zero(const void *s1, size_t len)
-{
- unsigned char same;
-
- len /= 4;
-
- __asm__ __volatile__
- ("repe; scasl;"
- "sete %0"
- : "=qm" (same), "+D" (s1), "+c" (len)
- : "a" (0)
- : "cc");
-
- return same;
-}
-
-
-#elif defined(CONFIG_X86_64)
-#define memcmp memcmpx86_64
-/*
- * Compare 8-byte-aligned address s1 and s2, with length n
- */
-int memcmpx86_64(void *s1, void *s2, size_t n)
-{
- size_t num = n / 8;
- register int res;
-
- __asm__ __volatile__
- (
- "testq %q3,%q3\n\t"
- "repe; cmpsq\n\t"
- "je 1f\n\t"
- "sbbq %q0,%q0\n\t"
- "orq $1,%q0\n"
- "1:"
- : "=&a" (res), "+&S" (s1), "+&D" (s2), "+&c" (num)
- : "0" (0)
- : "cc");
-
- return res;
-}
-
-static int is_full_zero(const void *s1, size_t len)
-{
- unsigned char same;
-
- len /= 8;
-
- __asm__ __volatile__
- ("repe; scasq;"
- "sete %0"
- : "=qm" (same), "+D" (s1), "+c" (len)
- : "a" (0)
- : "cc");
-
- return same;
-}
-
-#endif
-#else
-static int is_full_zero(const void *s1, size_t len)
-{
- unsigned long *src = s1;
- int i;
-
- len /= sizeof(*src);
-
- for (i = 0; i < len; i++) {
- if (src[i])
- return 0;
- }
-
- return 1;
-}
-#endif
-
-#define UKSM_RUNG_ROUND_FINISHED (1 << 0)
-#define TIME_RATIO_SCALE 10000
-
-#define SLOT_TREE_NODE_SHIFT 8
-#define SLOT_TREE_NODE_STORE_SIZE (1UL << SLOT_TREE_NODE_SHIFT)
-struct slot_tree_node {
- unsigned long size;
- struct sradix_tree_node snode;
- void *stores[SLOT_TREE_NODE_STORE_SIZE];
-};
-
-static struct kmem_cache *slot_tree_node_cachep;
-
-static struct sradix_tree_node *slot_tree_node_alloc(void)
-{
- struct slot_tree_node *p;
- p = kmem_cache_zalloc(slot_tree_node_cachep, GFP_KERNEL);
- if (!p)
- return NULL;
-
- return &p->snode;
-}
-
-static void slot_tree_node_free(struct sradix_tree_node *node)
-{
- struct slot_tree_node *p;
-
- p = container_of(node, struct slot_tree_node, snode);
- kmem_cache_free(slot_tree_node_cachep, p);
-}
-
-static void slot_tree_node_extend(struct sradix_tree_node *parent,
- struct sradix_tree_node *child)
-{
- struct slot_tree_node *p, *c;
-
- p = container_of(parent, struct slot_tree_node, snode);
- c = container_of(child, struct slot_tree_node, snode);
-
- p->size += c->size;
-}
-
-void slot_tree_node_assign(struct sradix_tree_node *node,
- unsigned index, void *item)
-{
- struct vma_slot *slot = item;
- struct slot_tree_node *cur;
-
- slot->snode = node;
- slot->sindex = index;
-
- while (node) {
- cur = container_of(node, struct slot_tree_node, snode);
- cur->size += slot->pages;
- node = node->parent;
- }
-}
-
-void slot_tree_node_rm(struct sradix_tree_node *node, unsigned offset)
-{
- struct vma_slot *slot;
- struct slot_tree_node *cur;
- unsigned long pages;
-
- if (node->height == 1) {
- slot = node->stores[offset];
- pages = slot->pages;
- } else {
- cur = container_of(node->stores[offset],
- struct slot_tree_node, snode);
- pages = cur->size;
- }
-
- while (node) {
- cur = container_of(node, struct slot_tree_node, snode);
- cur->size -= pages;
- node = node->parent;
- }
-}
-
-unsigned long slot_iter_index;
-int slot_iter(void *item, unsigned long height)
-{
- struct slot_tree_node *node;
- struct vma_slot *slot;
-
- if (height == 1) {
- slot = item;
- if (slot_iter_index < slot->pages) {
- /*in this one*/
- return 1;
- } else {
- slot_iter_index -= slot->pages;
- return 0;
- }
-
- } else {
- node = container_of(item, struct slot_tree_node, snode);
- if (slot_iter_index < node->size) {
- /*in this one*/
- return 1;
- } else {
- slot_iter_index -= node->size;
- return 0;
- }
- }
-}
-
-
-static inline void slot_tree_init_root(struct sradix_tree_root *root)
-{
- init_sradix_tree_root(root, SLOT_TREE_NODE_SHIFT);
- root->alloc = slot_tree_node_alloc;
- root->free = slot_tree_node_free;
- root->extend = slot_tree_node_extend;
- root->assign = slot_tree_node_assign;
- root->rm = slot_tree_node_rm;
-}
-
-void slot_tree_init(void)
-{
- slot_tree_node_cachep = kmem_cache_create("slot_tree_node",
- sizeof(struct slot_tree_node), 0,
- SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
- NULL);
-}
-
-
-/* Each rung of this ladder is a list of VMAs having a same scan ratio */
-struct scan_rung {
- //struct list_head scanned_list;
- struct sradix_tree_root vma_root;
- struct sradix_tree_root vma_root2;
-
- struct vma_slot *current_scan;
- unsigned long current_offset;
-
- /*
- * The initial value for current_offset, it should loop over
- * [0~ step - 1] to let all slot have its chance to be scanned.
- */
- unsigned long offset_init;
- unsigned long step; /* dynamic step for current_offset */
- unsigned int flags;
- unsigned long pages_to_scan;
- //unsigned long fully_scanned_slots;
- /*
- * a little bit tricky - if cpu_time_ratio > 0, then the value is the
- * the cpu time ratio it can spend in rung_i for every scan
- * period. if < 0, then it is the cpu time ratio relative to the
- * max cpu percentage user specified. Both in unit of
- * 1/TIME_RATIO_SCALE
- */
- int cpu_ratio;
-
- /*
- * How long it will take for all slots in this rung to be fully
- * scanned? If it's zero, we don't care about the cover time:
- * it's fully scanned.
- */
- unsigned int cover_msecs;
- //unsigned long vma_num;
- //unsigned long pages; /* Sum of all slot's pages in rung */
-};
-
-/**
- * node of either the stable or unstale rbtree
- *
- */
-struct tree_node {
- struct rb_node node; /* link in the main (un)stable rbtree */
- struct rb_root sub_root; /* rb_root for sublevel collision rbtree */
- u32 hash;
- unsigned long count; /* TODO: merged with sub_root */
- struct list_head all_list; /* all tree nodes in stable/unstable tree */
-};
-
-/**
- * struct stable_node - node of the stable rbtree
- * @node: rb node of this ksm page in the stable tree
- * @hlist: hlist head of rmap_items using this ksm page
- * @kpfn: page frame number of this ksm page
- */
-struct stable_node {
- struct rb_node node; /* link in sub-rbtree */
- struct tree_node *tree_node; /* it's tree node root in stable tree, NULL if it's in hell list */
- struct hlist_head hlist;
- unsigned long kpfn;
- u32 hash_max; /* if ==0 then it's not been calculated yet */
- struct list_head all_list; /* in a list for all stable nodes */
-};
-
-/**
- * struct node_vma - group rmap_items linked in a same stable
- * node together.
- */
-struct node_vma {
- union {
- struct vma_slot *slot;
- unsigned long key; /* slot is used as key sorted on hlist */
- };
- struct hlist_node hlist;
- struct hlist_head rmap_hlist;
- struct stable_node *head;
-};
-
-/**
- * struct rmap_item - reverse mapping item for virtual addresses
- * @rmap_list: next rmap_item in mm_slot's singly-linked rmap_list
- * @anon_vma: pointer to anon_vma for this mm,address, when in stable tree
- * @mm: the memory structure this rmap_item is pointing into
- * @address: the virtual address this rmap_item tracks (+ flags in low bits)
- * @node: rb node of this rmap_item in the unstable tree
- * @head: pointer to stable_node heading this list in the stable tree
- * @hlist: link into hlist of rmap_items hanging off that stable_node
- */
-struct rmap_item {
- struct vma_slot *slot;
- struct page *page;
- unsigned long address; /* + low bits used for flags below */
- unsigned long hash_round;
- unsigned long entry_index;
- union {
- struct {/* when in unstable tree */
- struct rb_node node;
- struct tree_node *tree_node;
- u32 hash_max;
- };
- struct { /* when in stable tree */
- struct node_vma *head;
- struct hlist_node hlist;
- struct anon_vma *anon_vma;
- };
- };
-} __attribute__((aligned(4)));
-
-struct rmap_list_entry {
- union {
- struct rmap_item *item;
- unsigned long addr;
- };
- /* lowest bit is used for is_addr tag */
-} __attribute__((aligned(4))); /* 4 aligned to fit in to pages*/
-
-
-/* Basic data structure definition ends */
-
-
-/*
- * Flags for rmap_item to judge if it's listed in the stable/unstable tree.
- * The flags use the low bits of rmap_item.address
- */
-#define UNSTABLE_FLAG 0x1
-#define STABLE_FLAG 0x2
-#define get_rmap_addr(x) ((x)->address & PAGE_MASK)
-
-/*
- * rmap_list_entry helpers
- */
-#define IS_ADDR_FLAG 1
-#define is_addr(ptr) ((unsigned long)(ptr) & IS_ADDR_FLAG)
-#define set_is_addr(ptr) ((ptr) |= IS_ADDR_FLAG)
-#define get_clean_addr(ptr) (((ptr) & ~(__typeof__(ptr))IS_ADDR_FLAG))
-
-
-/*
- * High speed caches for frequently allocated and freed structs
- */
-static struct kmem_cache *rmap_item_cache;
-static struct kmem_cache *stable_node_cache;
-static struct kmem_cache *node_vma_cache;
-static struct kmem_cache *vma_slot_cache;
-static struct kmem_cache *tree_node_cache;
-#define UKSM_KMEM_CACHE(__struct, __flags) kmem_cache_create("uksm_"#__struct,\
- sizeof(struct __struct), __alignof__(struct __struct),\
- (__flags), NULL)
-
-/* Array of all scan_rung, uksm_scan_ladder[0] having the minimum scan ratio */
-#define SCAN_LADDER_SIZE 4
-static struct scan_rung uksm_scan_ladder[SCAN_LADDER_SIZE];
-
-/* The evaluation rounds uksmd has finished */
-static unsigned long long uksm_eval_round = 1;
-
-/*
- * we add 1 to this var when we consider we should rebuild the whole
- * unstable tree.
- */
-static unsigned long uksm_hash_round = 1;
-
-/*
- * How many times the whole memory is scanned.
- */
-static unsigned long long fully_scanned_round = 1;
-
-/* The total number of virtual pages of all vma slots */
-static u64 uksm_pages_total;
-
-/* The number of pages has been scanned since the start up */
-static u64 uksm_pages_scanned;
-
-static u64 scanned_virtual_pages;
-
-/* The number of pages has been scanned since last encode_benefit call */
-static u64 uksm_pages_scanned_last;
-
-/* If the scanned number is tooo large, we encode it here */
-static u64 pages_scanned_stored;
-
-static unsigned long pages_scanned_base;
-
-/* The number of nodes in the stable tree */
-static unsigned long uksm_pages_shared;
-
-/* The number of page slots additionally sharing those nodes */
-static unsigned long uksm_pages_sharing;
-
-/* The number of nodes in the unstable tree */
-static unsigned long uksm_pages_unshared;
-
-/*
- * Milliseconds ksmd should sleep between scans,
- * >= 100ms to be consistent with
- * scan_time_to_sleep_msec()
- */
-static unsigned int uksm_sleep_jiffies;
-
-/* The real value for the uksmd next sleep */
-static unsigned int uksm_sleep_real;
-
-/* Saved value for user input uksm_sleep_jiffies when it's enlarged */
-static unsigned int uksm_sleep_saved;
-
-/* Max percentage of cpu utilization ksmd can take to scan in one batch */
-static unsigned int uksm_max_cpu_percentage;
-
-static int uksm_cpu_governor;
-
-static char *uksm_cpu_governor_str[4] = { "full", "medium", "low", "quiet" };
-
-struct uksm_cpu_preset_s {
- int cpu_ratio[SCAN_LADDER_SIZE];
- unsigned int cover_msecs[SCAN_LADDER_SIZE];
- unsigned int max_cpu; /* percentage */
-};
-
-struct uksm_cpu_preset_s uksm_cpu_preset[4] = {
- { {20, 40, -2500, -10000}, {1000, 500, 200, 50}, 95},
- { {20, 30, -2500, -10000}, {1000, 500, 400, 100}, 50},
- { {10, 20, -5000, -10000}, {1500, 1000, 1000, 250}, 20},
- { {10, 20, 40, 75}, {2000, 1000, 1000, 1000}, 1},
-};
-
-/* The default value for uksm_ema_page_time if it's not initialized */
-#define UKSM_PAGE_TIME_DEFAULT 500
-
-/*cost to scan one page by expotional moving average in nsecs */
-static unsigned long uksm_ema_page_time = UKSM_PAGE_TIME_DEFAULT;
-
-/* The expotional moving average alpha weight, in percentage. */
-#define EMA_ALPHA 20
-
-/*
- * The threshold used to filter out thrashing areas,
- * If it == 0, filtering is disabled, otherwise it's the percentage up-bound
- * of the thrashing ratio of all areas. Any area with a bigger thrashing ratio
- * will be considered as having a zero duplication ratio.
- */
-static unsigned int uksm_thrash_threshold = 50;
-
-/* How much dedup ratio is considered to be abundant*/
-static unsigned int uksm_abundant_threshold = 10;
-
-/* All slots having merged pages in this eval round. */
-struct list_head vma_slot_dedup = LIST_HEAD_INIT(vma_slot_dedup);
-
-/* How many times the ksmd has slept since startup */
-static unsigned long long uksm_sleep_times;
-
-#define UKSM_RUN_STOP 0
-#define UKSM_RUN_MERGE 1
-static unsigned int uksm_run = 1;
-
-static DECLARE_WAIT_QUEUE_HEAD(uksm_thread_wait);
-static DEFINE_MUTEX(uksm_thread_mutex);
-
-/*
- * List vma_slot_new is for newly created vma_slot waiting to be added by
- * ksmd. If one cannot be added(e.g. due to it's too small), it's moved to
- * vma_slot_noadd. vma_slot_del is the list for vma_slot whose corresponding
- * VMA has been removed/freed.
- */
-struct list_head vma_slot_new = LIST_HEAD_INIT(vma_slot_new);
-struct list_head vma_slot_noadd = LIST_HEAD_INIT(vma_slot_noadd);
-struct list_head vma_slot_del = LIST_HEAD_INIT(vma_slot_del);
-static DEFINE_SPINLOCK(vma_slot_list_lock);
-
-/* The unstable tree heads */
-static struct rb_root root_unstable_tree = RB_ROOT;
-
-/*
- * All tree_nodes are in a list to be freed at once when unstable tree is
- * freed after each scan round.
- */
-static struct list_head unstable_tree_node_list =
- LIST_HEAD_INIT(unstable_tree_node_list);
-
-/* List contains all stable nodes */
-static struct list_head stable_node_list = LIST_HEAD_INIT(stable_node_list);
-
-/*
- * When the hash strength is changed, the stable tree must be delta_hashed and
- * re-structured. We use two set of below structs to speed up the
- * re-structuring of stable tree.
- */
-static struct list_head
-stable_tree_node_list[2] = {LIST_HEAD_INIT(stable_tree_node_list[0]),
- LIST_HEAD_INIT(stable_tree_node_list[1])};
-
-static struct list_head *stable_tree_node_listp = &stable_tree_node_list[0];
-static struct rb_root root_stable_tree[2] = {RB_ROOT, RB_ROOT};
-static struct rb_root *root_stable_treep = &root_stable_tree[0];
-static unsigned long stable_tree_index;
-
-/* The hash strength needed to hash a full page */
-#define HASH_STRENGTH_FULL (PAGE_SIZE / sizeof(u32))
-
-/* The hash strength needed for loop-back hashing */
-#define HASH_STRENGTH_MAX (HASH_STRENGTH_FULL + 10)
-
-/* The random offsets in a page */
-static u32 *random_nums;
-
-/* The hash strength */
-static unsigned long hash_strength = HASH_STRENGTH_FULL >> 4;
-
-/* The delta value each time the hash strength increases or decreases */
-static unsigned long hash_strength_delta;
-#define HASH_STRENGTH_DELTA_MAX 5
-
-/* The time we have saved due to random_sample_hash */
-static u64 rshash_pos;
-
-/* The time we have wasted due to hash collision */
-static u64 rshash_neg;
-
-struct uksm_benefit {
- u64 pos;
- u64 neg;
- u64 scanned;
- unsigned long base;
-} benefit;
-
-/*
- * The relative cost of memcmp, compared to 1 time unit of random sample
- * hash, this value is tested when ksm module is initialized
- */
-static unsigned long memcmp_cost;
-
-static unsigned long rshash_neg_cont_zero;
-static unsigned long rshash_cont_obscure;
-
-/* The possible states of hash strength adjustment heuristic */
-enum rshash_states {
- RSHASH_STILL,
- RSHASH_TRYUP,
- RSHASH_TRYDOWN,
- RSHASH_NEW,
- RSHASH_PRE_STILL,
-};
-
-/* The possible direction we are about to adjust hash strength */
-enum rshash_direct {
- GO_UP,
- GO_DOWN,
- OBSCURE,
- STILL,
-};
-
-/* random sampling hash state machine */
-static struct {
- enum rshash_states state;
- enum rshash_direct pre_direct;
- u8 below_count;
- /* Keep a lookup window of size 5, iff above_count/below_count > 3
- * in this window we stop trying.
- */
- u8 lookup_window_index;
- u64 stable_benefit;
- unsigned long turn_point_down;
- unsigned long turn_benefit_down;
- unsigned long turn_point_up;
- unsigned long turn_benefit_up;
- unsigned long stable_point;
-} rshash_state;
-
-/*zero page hash table, hash_strength [0 ~ HASH_STRENGTH_MAX]*/
-static u32 *zero_hash_table;
-
-static inline struct node_vma *alloc_node_vma(void)
-{
- struct node_vma *node_vma;
- node_vma = kmem_cache_zalloc(node_vma_cache, GFP_KERNEL);
- if (node_vma) {
- INIT_HLIST_HEAD(&node_vma->rmap_hlist);
- INIT_HLIST_NODE(&node_vma->hlist);
- }
- return node_vma;
-}
-
-static inline void free_node_vma(struct node_vma *node_vma)
-{
- kmem_cache_free(node_vma_cache, node_vma);
-}
-
-
-static inline struct vma_slot *alloc_vma_slot(void)
-{
- struct vma_slot *slot;
-
- /*
- * In case ksm is not initialized by now.
- * Oops, we need to consider the call site of uksm_init() in the future.
- */
- if (!vma_slot_cache)
- return NULL;
-
- slot = kmem_cache_zalloc(vma_slot_cache, GFP_KERNEL);
- if (slot) {
- INIT_LIST_HEAD(&slot->slot_list);
- INIT_LIST_HEAD(&slot->dedup_list);
- slot->flags |= UKSM_SLOT_NEED_RERAND;
- }
- return slot;
-}
-
-static inline void free_vma_slot(struct vma_slot *vma_slot)
-{
- kmem_cache_free(vma_slot_cache, vma_slot);
-}
-
-
-
-static inline struct rmap_item *alloc_rmap_item(void)
-{
- struct rmap_item *rmap_item;
-
- rmap_item = kmem_cache_zalloc(rmap_item_cache, GFP_KERNEL);
- if (rmap_item) {
- /* bug on lowest bit is not clear for flag use */
- BUG_ON(is_addr(rmap_item));
- }
- return rmap_item;
-}
-
-static inline void free_rmap_item(struct rmap_item *rmap_item)
-{
- rmap_item->slot = NULL; /* debug safety */
- kmem_cache_free(rmap_item_cache, rmap_item);
-}
-
-static inline struct stable_node *alloc_stable_node(void)
-{
- struct stable_node *node;
- node = kmem_cache_alloc(stable_node_cache, GFP_KERNEL | GFP_ATOMIC);
- if (!node)
- return NULL;
-
- INIT_HLIST_HEAD(&node->hlist);
- list_add(&node->all_list, &stable_node_list);
- return node;
-}
-
-static inline void free_stable_node(struct stable_node *stable_node)
-{
- list_del(&stable_node->all_list);
- kmem_cache_free(stable_node_cache, stable_node);
-}
-
-static inline struct tree_node *alloc_tree_node(struct list_head *list)
-{
- struct tree_node *node;
- node = kmem_cache_zalloc(tree_node_cache, GFP_KERNEL | GFP_ATOMIC);
- if (!node)
- return NULL;
-
- list_add(&node->all_list, list);
- return node;
-}
-
-static inline void free_tree_node(struct tree_node *node)
-{
- list_del(&node->all_list);
- kmem_cache_free(tree_node_cache, node);
-}
-
-static void uksm_drop_anon_vma(struct rmap_item *rmap_item)
-{
- struct anon_vma *anon_vma = rmap_item->anon_vma;
-
- put_anon_vma(anon_vma);
-}
-
-
-/**
- * Remove a stable node from stable_tree, may unlink from its tree_node and
- * may remove its parent tree_node if no other stable node is pending.
- *
- * @stable_node The node need to be removed
- * @unlink_rb Will this node be unlinked from the rbtree?
- * @remove_tree_ node Will its tree_node be removed if empty?
- */
-static void remove_node_from_stable_tree(struct stable_node *stable_node,
- int unlink_rb, int remove_tree_node)
-{
- struct node_vma *node_vma;
- struct rmap_item *rmap_item;
- struct hlist_node *n;
-
- if (!hlist_empty(&stable_node->hlist)) {
- hlist_for_each_entry_safe(node_vma, n,
- &stable_node->hlist, hlist) {
- hlist_for_each_entry(rmap_item, &node_vma->rmap_hlist, hlist) {
- uksm_pages_sharing--;
-
- uksm_drop_anon_vma(rmap_item);
- rmap_item->address &= PAGE_MASK;
- }
- free_node_vma(node_vma);
- cond_resched();
- }
-
- /* the last one is counted as shared */
- uksm_pages_shared--;
- uksm_pages_sharing++;
- }
-
- if (stable_node->tree_node && unlink_rb) {
- rb_erase(&stable_node->node,
- &stable_node->tree_node->sub_root);
-
- if (RB_EMPTY_ROOT(&stable_node->tree_node->sub_root) &&
- remove_tree_node) {
- rb_erase(&stable_node->tree_node->node,
- root_stable_treep);
- free_tree_node(stable_node->tree_node);
- } else {
- stable_node->tree_node->count--;
- }
- }
-
- free_stable_node(stable_node);
-}
-
-
-/*
- * get_uksm_page: checks if the page indicated by the stable node
- * is still its ksm page, despite having held no reference to it.
- * In which case we can trust the content of the page, and it
- * returns the gotten page; but if the page has now been zapped,
- * remove the stale node from the stable tree and return NULL.
- *
- * You would expect the stable_node to hold a reference to the ksm page.
- * But if it increments the page's count, swapping out has to wait for
- * ksmd to come around again before it can free the page, which may take
- * seconds or even minutes: much too unresponsive. So instead we use a
- * "keyhole reference": access to the ksm page from the stable node peeps
- * out through its keyhole to see if that page still holds the right key,
- * pointing back to this stable node. This relies on freeing a PageAnon
- * page to reset its page->mapping to NULL, and relies on no other use of
- * a page to put something that might look like our key in page->mapping.
- *
- * include/linux/pagemap.h page_cache_get_speculative() is a good reference,
- * but this is different - made simpler by uksm_thread_mutex being held, but
- * interesting for assuming that no other use of the struct page could ever
- * put our expected_mapping into page->mapping (or a field of the union which
- * coincides with page->mapping). The RCU calls are not for KSM at all, but
- * to keep the page_count protocol described with page_cache_get_speculative.
- *
- * Note: it is possible that get_uksm_page() will return NULL one moment,
- * then page the next, if the page is in between page_freeze_refs() and
- * page_unfreeze_refs(): this shouldn't be a problem anywhere, the page
- * is on its way to being freed; but it is an anomaly to bear in mind.
- *
- * @unlink_rb: if the removal of this node will firstly unlink from
- * its rbtree. stable_node_reinsert will prevent this when restructuring the
- * node from its old tree.
- *
- * @remove_tree_node: if this is the last one of its tree_node, will the
- * tree_node be freed ? If we are inserting stable node, this tree_node may
- * be reused, so don't free it.
- */
-static struct page *get_uksm_page(struct stable_node *stable_node,
- int unlink_rb, int remove_tree_node)
-{
- struct page *page;
- void *expected_mapping;
-
- page = pfn_to_page(stable_node->kpfn);
- expected_mapping = (void *)stable_node +
- (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM);
- rcu_read_lock();
- if (page->mapping != expected_mapping)
- goto stale;
- if (!get_page_unless_zero(page))
- goto stale;
- if (page->mapping != expected_mapping) {
- put_page(page);
- goto stale;
- }
- rcu_read_unlock();
- return page;
-stale:
- rcu_read_unlock();
- remove_node_from_stable_tree(stable_node, unlink_rb, remove_tree_node);
-
- return NULL;
-}
-
-/*
- * Removing rmap_item from stable or unstable tree.
- * This function will clean the information from the stable/unstable tree.
- */
-static inline void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
-{
- if (rmap_item->address & STABLE_FLAG) {
- struct stable_node *stable_node;
- struct node_vma *node_vma;
- struct page *page;
-
- node_vma = rmap_item->head;
- stable_node = node_vma->head;
- page = get_uksm_page(stable_node, 1, 1);
- if (!page)
- goto out;
-
- /*
- * page lock is needed because it's racing with
- * try_to_unmap_ksm(), etc.
- */
- lock_page(page);
- hlist_del(&rmap_item->hlist);
-
- if (hlist_empty(&node_vma->rmap_hlist)) {
- hlist_del(&node_vma->hlist);
- free_node_vma(node_vma);
- }
- unlock_page(page);
-
- put_page(page);
- if (hlist_empty(&stable_node->hlist)) {
- /* do NOT call remove_node_from_stable_tree() here,
- * it's possible for a forked rmap_item not in
- * stable tree while the in-tree rmap_items were
- * deleted.
- */
- uksm_pages_shared--;
- } else
- uksm_pages_sharing--;
-
-
- uksm_drop_anon_vma(rmap_item);
- } else if (rmap_item->address & UNSTABLE_FLAG) {
- if (rmap_item->hash_round == uksm_hash_round) {
-
- rb_erase(&rmap_item->node,
- &rmap_item->tree_node->sub_root);
- if (RB_EMPTY_ROOT(&rmap_item->tree_node->sub_root)) {
- rb_erase(&rmap_item->tree_node->node,
- &root_unstable_tree);
-
- free_tree_node(rmap_item->tree_node);
- } else
- rmap_item->tree_node->count--;
- }
- uksm_pages_unshared--;
- }
-
- rmap_item->address &= PAGE_MASK;
- rmap_item->hash_max = 0;
-
-out:
- cond_resched(); /* we're called from many long loops */
-}
-
-static inline int slot_in_uksm(struct vma_slot *slot)
-{
- return list_empty(&slot->slot_list);
-}
-
-/*
- * Test if the mm is exiting
- */
-static inline bool uksm_test_exit(struct mm_struct *mm)
-{
- return atomic_read(&mm->mm_users) == 0;
-}
-
-static inline unsigned long vma_pool_size(struct vma_slot *slot)
-{
- return round_up(sizeof(struct rmap_list_entry) * slot->pages,
- PAGE_SIZE) >> PAGE_SHIFT;
-}
-
-#define CAN_OVERFLOW_U64(x, delta) (U64_MAX - (x) < (delta))
-
-/* must be done with sem locked */
-static int slot_pool_alloc(struct vma_slot *slot)
-{
- unsigned long pool_size;
-
- if (slot->rmap_list_pool)
- return 0;
-
- pool_size = vma_pool_size(slot);
- slot->rmap_list_pool = kzalloc(sizeof(struct page *) *
- pool_size, GFP_KERNEL);
- if (!slot->rmap_list_pool)
- return -ENOMEM;
-
- slot->pool_counts = kzalloc(sizeof(unsigned int) * pool_size,
- GFP_KERNEL);
- if (!slot->pool_counts) {
- kfree(slot->rmap_list_pool);
- return -ENOMEM;
- }
-
- slot->pool_size = pool_size;
- BUG_ON(CAN_OVERFLOW_U64(uksm_pages_total, slot->pages));
- slot->flags |= UKSM_SLOT_IN_UKSM;
- uksm_pages_total += slot->pages;
-
- return 0;
-}
-
-/*
- * Called after vma is unlinked from its mm
- */
-void uksm_remove_vma(struct vm_area_struct *vma)
-{
- struct vma_slot *slot;
-
- if (!vma->uksm_vma_slot)
- return;
-
- spin_lock(&vma_slot_list_lock);
- slot = vma->uksm_vma_slot;
- if (!slot)
- goto out;
-
- if (slot_in_uksm(slot)) {
- /**
- * This slot has been added by ksmd, so move to the del list
- * waiting ksmd to free it.
- */
- list_add_tail(&slot->slot_list, &vma_slot_del);
- } else {
- /**
- * It's still on new list. It's ok to free slot directly.
- */
- list_del(&slot->slot_list);
- free_vma_slot(slot);
- }
-out:
- vma->uksm_vma_slot = NULL;
- spin_unlock(&vma_slot_list_lock);
-}
-
-/**
- * Need to do two things:
- * 1. check if slot was moved to del list
- * 2. make sure the mmap_sem is manipulated under valid vma.
- *
- * My concern here is that in some cases, this may make
- * vma_slot_list_lock() waiters to serialized further by some
- * sem->wait_lock, can this really be expensive?
- *
- *
- * @return
- * 0: if successfully locked mmap_sem
- * -ENOENT: this slot was moved to del list
- * -EBUSY: vma lock failed
- */
-static int try_down_read_slot_mmap_sem(struct vma_slot *slot)
-{
- struct vm_area_struct *vma;
- struct mm_struct *mm;
- struct rw_semaphore *sem;
-
- spin_lock(&vma_slot_list_lock);
-
- /* the slot_list was removed and inited from new list, when it enters
- * uksm_list. If now it's not empty, then it must be moved to del list
- */
- if (!slot_in_uksm(slot)) {
- spin_unlock(&vma_slot_list_lock);
- return -ENOENT;
- }
-
- BUG_ON(slot->pages != vma_pages(slot->vma));
- /* Ok, vma still valid */
- vma = slot->vma;
- mm = vma->vm_mm;
- sem = &mm->mmap_sem;
-
- if (uksm_test_exit(mm)) {
- spin_unlock(&vma_slot_list_lock);
- return -ENOENT;
- }
-
- if (down_read_trylock(sem)) {
- spin_unlock(&vma_slot_list_lock);
- if (slot_pool_alloc(slot)) {
- uksm_remove_vma(vma);
- up_read(sem);
- return -ENOENT;
- }
- return 0;
- }
-
- spin_unlock(&vma_slot_list_lock);
- return -EBUSY;
-}
-
-static inline unsigned long
-vma_page_address(struct page *page, struct vm_area_struct *vma)
-{
- pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
- unsigned long address;
-
- address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
- if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
- /* page should be within @vma mapping range */
- return -EFAULT;
- }
- return address;
-}
-
-
-/* return 0 on success with the item's mmap_sem locked */
-static inline int get_mergeable_page_lock_mmap(struct rmap_item *item)
-{
- struct mm_struct *mm;
- struct vma_slot *slot = item->slot;
- int err = -EINVAL;
-
- struct page *page;
-
- /*
- * try_down_read_slot_mmap_sem() returns non-zero if the slot
- * has been removed by uksm_remove_vma().
- */
- if (try_down_read_slot_mmap_sem(slot))
- return -EBUSY;
-
- mm = slot->vma->vm_mm;
-
- if (uksm_test_exit(mm))
- goto failout_up;
-
- page = item->page;
- rcu_read_lock();
- if (!get_page_unless_zero(page)) {
- rcu_read_unlock();
- goto failout_up;
- }
-
- /* No need to consider huge page here. */
- if (item->slot->vma->anon_vma != page_anon_vma(page) ||
- vma_page_address(page, item->slot->vma) != get_rmap_addr(item)) {
- /*
- * TODO:
- * should we release this item becase of its stale page
- * mapping?
- */
- put_page(page);
- rcu_read_unlock();
- goto failout_up;
- }
- rcu_read_unlock();
- return 0;
-
-failout_up:
- up_read(&mm->mmap_sem);
- return err;
-}
-
-/*
- * What kind of VMA is considered ?
- */
-static inline int vma_can_enter(struct vm_area_struct *vma)
-{
- return uksm_flags_can_scan(vma->vm_flags);
-}
-
-/*
- * Called whenever a fresh new vma is created A new vma_slot.
- * is created and inserted into a global list Must be called.
- * after vma is inserted to its mm .
- */
-void uksm_vma_add_new(struct vm_area_struct *vma)
-{
- struct vma_slot *slot;
-
- if (!vma_can_enter(vma)) {
- vma->uksm_vma_slot = NULL;
- return;
- }
-
- slot = alloc_vma_slot();
- if (!slot) {
- vma->uksm_vma_slot = NULL;
- return;
- }
-
- vma->uksm_vma_slot = slot;
- vma->vm_flags |= VM_MERGEABLE;
- slot->vma = vma;
- slot->mm = vma->vm_mm;
- slot->ctime_j = jiffies;
- slot->pages = vma_pages(vma);
- spin_lock(&vma_slot_list_lock);
- list_add_tail(&slot->slot_list, &vma_slot_new);
- spin_unlock(&vma_slot_list_lock);
-}
-
-/* 32/3 < they < 32/2 */
-#define shiftl 8
-#define shiftr 12
-
-#define HASH_FROM_TO(from, to) \
-for (index = from; index < to; index++) { \
- pos = random_nums[index]; \
- hash += key[pos]; \
- hash += (hash << shiftl); \
- hash ^= (hash >> shiftr); \
-}
-
-
-#define HASH_FROM_DOWN_TO(from, to) \
-for (index = from - 1; index >= to; index--) { \
- hash ^= (hash >> shiftr); \
- hash ^= (hash >> (shiftr*2)); \
- hash -= (hash << shiftl); \
- hash += (hash << (shiftl*2)); \
- pos = random_nums[index]; \
- hash -= key[pos]; \
-}
-
-/*
- * The main random sample hash function.
- */
-static u32 random_sample_hash(void *addr, u32 hash_strength)
-{
- u32 hash = 0xdeadbeef;
- int index, pos, loop = hash_strength;
- u32 *key = (u32 *)addr;
-
- if (loop > HASH_STRENGTH_FULL)
- loop = HASH_STRENGTH_FULL;
-
- HASH_FROM_TO(0, loop);
-
- if (hash_strength > HASH_STRENGTH_FULL) {
- loop = hash_strength - HASH_STRENGTH_FULL;
- HASH_FROM_TO(0, loop);
- }
-
- return hash;
-}
-
-
-/**
- * It's used when hash strength is adjusted
- *
- * @addr The page's virtual address
- * @from The original hash strength
- * @to The hash strength changed to
- * @hash The hash value generated with "from" hash value
- *
- * return the hash value
- */
-static u32 delta_hash(void *addr, int from, int to, u32 hash)
-{
- u32 *key = (u32 *)addr;
- int index, pos; /* make sure they are int type */
-
- if (to > from) {
- if (from >= HASH_STRENGTH_FULL) {
- from -= HASH_STRENGTH_FULL;
- to -= HASH_STRENGTH_FULL;
- HASH_FROM_TO(from, to);
- } else if (to <= HASH_STRENGTH_FULL) {
- HASH_FROM_TO(from, to);
- } else {
- HASH_FROM_TO(from, HASH_STRENGTH_FULL);
- HASH_FROM_TO(0, to - HASH_STRENGTH_FULL);
- }
- } else {
- if (from <= HASH_STRENGTH_FULL) {
- HASH_FROM_DOWN_TO(from, to);
- } else if (to >= HASH_STRENGTH_FULL) {
- from -= HASH_STRENGTH_FULL;
- to -= HASH_STRENGTH_FULL;
- HASH_FROM_DOWN_TO(from, to);
- } else {
- HASH_FROM_DOWN_TO(from - HASH_STRENGTH_FULL, 0);
- HASH_FROM_DOWN_TO(HASH_STRENGTH_FULL, to);
- }
- }
-
- return hash;
-}
-
-/**
- *
- * Called when: rshash_pos or rshash_neg is about to overflow or a scan round
- * has finished.
- *
- * return 0 if no page has been scanned since last call, 1 otherwise.
- */
-static inline int encode_benefit(void)
-{
- u64 scanned_delta, pos_delta, neg_delta;
- unsigned long base = benefit.base;
-
- scanned_delta = uksm_pages_scanned - uksm_pages_scanned_last;
-
- if (!scanned_delta)
- return 0;
-
- scanned_delta >>= base;
- pos_delta = rshash_pos >> base;
- neg_delta = rshash_neg >> base;
-
- if (CAN_OVERFLOW_U64(benefit.pos, pos_delta) ||
- CAN_OVERFLOW_U64(benefit.neg, neg_delta) ||
- CAN_OVERFLOW_U64(benefit.scanned, scanned_delta)) {
- benefit.scanned >>= 1;
- benefit.neg >>= 1;
- benefit.pos >>= 1;
- benefit.base++;
- scanned_delta >>= 1;
- pos_delta >>= 1;
- neg_delta >>= 1;
- }
-
- benefit.pos += pos_delta;
- benefit.neg += neg_delta;
- benefit.scanned += scanned_delta;
-
- BUG_ON(!benefit.scanned);
-
- rshash_pos = rshash_neg = 0;
- uksm_pages_scanned_last = uksm_pages_scanned;
-
- return 1;
-}
-
-static inline void reset_benefit(void)
-{
- benefit.pos = 0;
- benefit.neg = 0;
- benefit.base = 0;
- benefit.scanned = 0;
-}
-
-static inline void inc_rshash_pos(unsigned long delta)
-{
- if (CAN_OVERFLOW_U64(rshash_pos, delta))
- encode_benefit();
-
- rshash_pos += delta;
-}
-
-static inline void inc_rshash_neg(unsigned long delta)
-{
- if (CAN_OVERFLOW_U64(rshash_neg, delta))
- encode_benefit();
-
- rshash_neg += delta;
-}
-
-
-static inline u32 page_hash(struct page *page, unsigned long hash_strength,
- int cost_accounting)
-{
- u32 val;
- unsigned long delta;
-
- void *addr = kmap_atomic(page);
-
- val = random_sample_hash(addr, hash_strength);
- kunmap_atomic(addr);
-
- if (cost_accounting) {
- if (HASH_STRENGTH_FULL > hash_strength)
- delta = HASH_STRENGTH_FULL - hash_strength;
- else
- delta = 0;
-
- inc_rshash_pos(delta);
- }
-
- return val;
-}
-
-static int memcmp_pages(struct page *page1, struct page *page2,
- int cost_accounting)
-{
- char *addr1, *addr2;
- int ret;
-
- addr1 = kmap_atomic(page1);
- addr2 = kmap_atomic(page2);
- ret = memcmp(addr1, addr2, PAGE_SIZE);
- kunmap_atomic(addr2);
- kunmap_atomic(addr1);
-
- if (cost_accounting)
- inc_rshash_neg(memcmp_cost);
-
- return ret;
-}
-
-static inline int pages_identical(struct page *page1, struct page *page2)
-{
- return !memcmp_pages(page1, page2, 0);
-}
-
-static inline int is_page_full_zero(struct page *page)
-{
- char *addr;
- int ret;
-
- addr = kmap_atomic(page);
- ret = is_full_zero(addr, PAGE_SIZE);
- kunmap_atomic(addr);
-
- return ret;
-}
-
-static int write_protect_page(struct vm_area_struct *vma, struct page *page,
- pte_t *orig_pte, pte_t *old_pte)
-{
- struct mm_struct *mm = vma->vm_mm;
- unsigned long addr;
- pte_t *ptep;
- spinlock_t *ptl;
- int swapped;
- int err = -EFAULT;
- unsigned long mmun_start; /* For mmu_notifiers */
- unsigned long mmun_end; /* For mmu_notifiers */
-
- addr = page_address_in_vma(page, vma);
- if (addr == -EFAULT)
- goto out;
-
- BUG_ON(PageTransCompound(page));
-
- mmun_start = addr;
- mmun_end = addr + PAGE_SIZE;
- mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
-
- ptep = page_check_address(page, mm, addr, &ptl, 0);
- if (!ptep)
- goto out_mn;
-
- if (old_pte)
- *old_pte = *ptep;
-
- if (pte_write(*ptep) || pte_dirty(*ptep)) {
- pte_t entry;
-
- swapped = PageSwapCache(page);
- flush_cache_page(vma, addr, page_to_pfn(page));
- /*
- * Ok this is tricky, when get_user_pages_fast() run it doesnt
- * take any lock, therefore the check that we are going to make
- * with the pagecount against the mapcount is racey and
- * O_DIRECT can happen right after the check.
- * So we clear the pte and flush the tlb before the check
- * this assure us that no O_DIRECT can happen after the check
- * or in the middle of the check.
- */
- entry = ptep_clear_flush_notify(vma, addr, ptep);
- /*
- * Check that no O_DIRECT or similar I/O is in progress on the
- * page
- */
- if (page_mapcount(page) + 1 + swapped != page_count(page)) {
- set_pte_at(mm, addr, ptep, entry);
- goto out_unlock;
- }
- if (pte_dirty(entry))
- set_page_dirty(page);
- entry = pte_mkclean(pte_wrprotect(entry));
- set_pte_at_notify(mm, addr, ptep, entry);
- }
- *orig_pte = *ptep;
- err = 0;
-
-out_unlock:
- pte_unmap_unlock(ptep, ptl);
-out_mn:
- mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
-out:
- return err;
-}
-
-#define MERGE_ERR_PGERR 1 /* the page is invalid cannot continue */
-#define MERGE_ERR_COLLI 2 /* there is a collision */
-#define MERGE_ERR_COLLI_MAX 3 /* collision at the max hash strength */
-#define MERGE_ERR_CHANGED 4 /* the page has changed since last hash */
-
-
-/**
- * replace_page - replace page in vma by new ksm page
- * @vma: vma that holds the pte pointing to page
- * @page: the page we are replacing by kpage
- * @kpage: the ksm page we replace page by
- * @orig_pte: the original value of the pte
- *
- * Returns 0 on success, MERGE_ERR_PGERR on failure.
- */
-static int replace_page(struct vm_area_struct *vma, struct page *page,
- struct page *kpage, pte_t orig_pte)
-{
- struct mm_struct *mm = vma->vm_mm;
- pgd_t *pgd;
- pud_t *pud;
- pmd_t *pmd;
- pte_t *ptep;
- spinlock_t *ptl;
- pte_t entry;
-
- unsigned long addr;
- int err = MERGE_ERR_PGERR;
- unsigned long mmun_start; /* For mmu_notifiers */
- unsigned long mmun_end; /* For mmu_notifiers */
-
- addr = page_address_in_vma(page, vma);
- if (addr == -EFAULT)
- goto out;
-
- pgd = pgd_offset(mm, addr);
- if (!pgd_present(*pgd))
- goto out;
-
- pud = pud_offset(pgd, addr);
- if (!pud_present(*pud))
- goto out;
-
- pmd = pmd_offset(pud, addr);
- BUG_ON(pmd_trans_huge(*pmd));
- if (!pmd_present(*pmd))
- goto out;
-
- mmun_start = addr;
- mmun_end = addr + PAGE_SIZE;
- mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
-
- ptep = pte_offset_map_lock(mm, pmd, addr, &ptl);
- if (!pte_same(*ptep, orig_pte)) {
- pte_unmap_unlock(ptep, ptl);
- goto out_mn;
- }
-
- flush_cache_page(vma, addr, pte_pfn(*ptep));
- ptep_clear_flush_notify(vma, addr, ptep);
- entry = mk_pte(kpage, vma->vm_page_prot);
-
- /* special treatment is needed for zero_page */
- if ((page_to_pfn(kpage) == uksm_zero_pfn) ||
- (page_to_pfn(kpage) == zero_pfn))
- entry = pte_mkspecial(entry);
- else {
- get_page(kpage);
- page_add_anon_rmap(kpage, vma, addr);
- }
-
- set_pte_at_notify(mm, addr, ptep, entry);
-
- page_remove_rmap(page);
- if (!page_mapped(page))
- try_to_free_swap(page);
- put_page(page);
-
- pte_unmap_unlock(ptep, ptl);
- err = 0;
-out_mn:
- mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
-out:
- return err;
-}
-
-
-/**
- * Fully hash a page with HASH_STRENGTH_MAX return a non-zero hash value. The
- * zero hash value at HASH_STRENGTH_MAX is used to indicated that its
- * hash_max member has not been calculated.
- *
- * @page The page needs to be hashed
- * @hash_old The hash value calculated with current hash strength
- *
- * return the new hash value calculated at HASH_STRENGTH_MAX
- */
-static inline u32 page_hash_max(struct page *page, u32 hash_old)
-{
- u32 hash_max = 0;
- void *addr;
-
- addr = kmap_atomic(page);
- hash_max = delta_hash(addr, hash_strength,
- HASH_STRENGTH_MAX, hash_old);
-
- kunmap_atomic(addr);
-
- if (!hash_max)
- hash_max = 1;
-
- inc_rshash_neg(HASH_STRENGTH_MAX - hash_strength);
- return hash_max;
-}
-
-/*
- * We compare the hash again, to ensure that it is really a hash collision
- * instead of being caused by page write.
- */
-static inline int check_collision(struct rmap_item *rmap_item,
- u32 hash)
-{
- int err;
- struct page *page = rmap_item->page;
-
- /* if this rmap_item has already been hash_maxed, then the collision
- * must appears in the second-level rbtree search. In this case we check
- * if its hash_max value has been changed. Otherwise, the collision
- * happens in the first-level rbtree search, so we check against it's
- * current hash value.
- */
- if (rmap_item->hash_max) {
- inc_rshash_neg(memcmp_cost);
- inc_rshash_neg(HASH_STRENGTH_MAX - hash_strength);
-
- if (rmap_item->hash_max == page_hash_max(page, hash))
- err = MERGE_ERR_COLLI;
- else
- err = MERGE_ERR_CHANGED;
- } else {
- inc_rshash_neg(memcmp_cost + hash_strength);
-
- if (page_hash(page, hash_strength, 0) == hash)
- err = MERGE_ERR_COLLI;
- else
- err = MERGE_ERR_CHANGED;
- }
-
- return err;
-}
-
-static struct page *page_trans_compound_anon(struct page *page)
-{
- if (PageTransCompound(page)) {
- struct page *head = compound_head(page);
- /*
- * head may actually be splitted and freed from under
- * us but it's ok here.
- */
- if (PageAnon(head))
- return head;
- }
- return NULL;
-}
-
-static int page_trans_compound_anon_split(struct page *page)
-{
- int ret = 0;
- struct page *transhuge_head = page_trans_compound_anon(page);
- if (transhuge_head) {
- /* Get the reference on the head to split it. */
- if (get_page_unless_zero(transhuge_head)) {
- /*
- * Recheck we got the reference while the head
- * was still anonymous.
- */
- if (PageAnon(transhuge_head))
- ret = split_huge_page(transhuge_head);
- else
- /*
- * Retry later if split_huge_page run
- * from under us.
- */
- ret = 1;
- put_page(transhuge_head);
- } else
- /* Retry later if split_huge_page run from under us. */
- ret = 1;
- }
- return ret;
-}
-
-/**
- * Try to merge a rmap_item.page with a kpage in stable node. kpage must
- * already be a ksm page.
- *
- * @return 0 if the pages were merged, -EFAULT otherwise.
- */
-static int try_to_merge_with_uksm_page(struct rmap_item *rmap_item,
- struct page *kpage, u32 hash)
-{
- struct vm_area_struct *vma = rmap_item->slot->vma;
- struct mm_struct *mm = vma->vm_mm;
- pte_t orig_pte = __pte(0);
- int err = MERGE_ERR_PGERR;
- struct page *page;
-
- if (uksm_test_exit(mm))
- goto out;
-
- page = rmap_item->page;
-
- if (page == kpage) { /* ksm page forked */
- err = 0;
- goto out;
- }
-
- if (PageTransCompound(page) && page_trans_compound_anon_split(page))
- goto out;
- BUG_ON(PageTransCompound(page));
-
- if (!PageAnon(page) || !PageKsm(kpage))
- goto out;
-
- /*
- * We need the page lock to read a stable PageSwapCache in
- * write_protect_page(). We use trylock_page() instead of
- * lock_page() because we don't want to wait here - we
- * prefer to continue scanning and merging different pages,
- * then come back to this page when it is unlocked.
- */
- if (!trylock_page(page))
- goto out;
- /*
- * If this anonymous page is mapped only here, its pte may need
- * to be write-protected. If it's mapped elsewhere, all of its
- * ptes are necessarily already write-protected. But in either
- * case, we need to lock and check page_count is not raised.
- */
- if (write_protect_page(vma, page, &orig_pte, NULL) == 0) {
- if (pages_identical(page, kpage))
- err = replace_page(vma, page, kpage, orig_pte);
- else
- err = check_collision(rmap_item, hash);
- }
-
- if ((vma->vm_flags & VM_LOCKED) && kpage && !err) {
- munlock_vma_page(page);
- if (!PageMlocked(kpage)) {
- unlock_page(page);
- lock_page(kpage);
- mlock_vma_page(kpage);
- page = kpage; /* for final unlock */
- }
- }
-
- unlock_page(page);
-out:
- return err;
-}
-
-
-
-/**
- * If two pages fail to merge in try_to_merge_two_pages, then we have a chance
- * to restore a page mapping that has been changed in try_to_merge_two_pages.
- *
- * @return 0 on success.
- */
-static int restore_uksm_page_pte(struct vm_area_struct *vma, unsigned long addr,
- pte_t orig_pte, pte_t wprt_pte)
-{
- struct mm_struct *mm = vma->vm_mm;
- pgd_t *pgd;
- pud_t *pud;
- pmd_t *pmd;
- pte_t *ptep;
- spinlock_t *ptl;
-
- int err = -EFAULT;
-
- pgd = pgd_offset(mm, addr);
- if (!pgd_present(*pgd))
- goto out;
-
- pud = pud_offset(pgd, addr);
- if (!pud_present(*pud))
- goto out;
-
- pmd = pmd_offset(pud, addr);
- if (!pmd_present(*pmd))
- goto out;
-
- ptep = pte_offset_map_lock(mm, pmd, addr, &ptl);
- if (!pte_same(*ptep, wprt_pte)) {
- /* already copied, let it be */
- pte_unmap_unlock(ptep, ptl);
- goto out;
- }
-
- /*
- * Good boy, still here. When we still get the ksm page, it does not
- * return to the free page pool, there is no way that a pte was changed
- * to other page and gets back to this page. And remind that ksm page
- * do not reuse in do_wp_page(). So it's safe to restore the original
- * pte.
- */
- flush_cache_page(vma, addr, pte_pfn(*ptep));
- ptep_clear_flush_notify(vma, addr, ptep);
- set_pte_at_notify(mm, addr, ptep, orig_pte);
-
- pte_unmap_unlock(ptep, ptl);
- err = 0;
-out:
- return err;
-}
-
-/**
- * try_to_merge_two_pages() - take two identical pages and prepare
- * them to be merged into one page(rmap_item->page)
- *
- * @return 0 if we successfully merged two identical pages into
- * one ksm page. MERGE_ERR_COLLI if it's only a hash collision
- * search in rbtree. MERGE_ERR_CHANGED if rmap_item has been
- * changed since it's hashed. MERGE_ERR_PGERR otherwise.
- *
- */
-static int try_to_merge_two_pages(struct rmap_item *rmap_item,
- struct rmap_item *tree_rmap_item,
- u32 hash)
-{
- pte_t orig_pte1 = __pte(0), orig_pte2 = __pte(0);
- pte_t wprt_pte1 = __pte(0), wprt_pte2 = __pte(0);
- struct vm_area_struct *vma1 = rmap_item->slot->vma;
- struct vm_area_struct *vma2 = tree_rmap_item->slot->vma;
- struct page *page = rmap_item->page;
- struct page *tree_page = tree_rmap_item->page;
- int err = MERGE_ERR_PGERR;
- struct address_space *saved_mapping;
-
-
- if (rmap_item->page == tree_rmap_item->page)
- goto out;
-
- if (PageTransCompound(page) && page_trans_compound_anon_split(page))
- goto out;
- BUG_ON(PageTransCompound(page));
-
- if (PageTransCompound(tree_page) && page_trans_compound_anon_split(tree_page))
- goto out;
- BUG_ON(PageTransCompound(tree_page));
-
- if (!PageAnon(page) || !PageAnon(tree_page))
- goto out;
-
- if (!trylock_page(page))
- goto out;
-
-
- if (write_protect_page(vma1, page, &wprt_pte1, &orig_pte1) != 0) {
- unlock_page(page);
- goto out;
- }
-
- /*
- * While we hold page lock, upgrade page from
- * PageAnon+anon_vma to PageKsm+NULL stable_node:
- * stable_tree_insert() will update stable_node.
- */
- saved_mapping = page->mapping;
- set_page_stable_node(page, NULL);
- mark_page_accessed(page);
- unlock_page(page);
-
- if (!trylock_page(tree_page))
- goto restore_out;
-
- if (write_protect_page(vma2, tree_page, &wprt_pte2, &orig_pte2) != 0) {
- unlock_page(tree_page);
- goto restore_out;
- }
-
- if (pages_identical(page, tree_page)) {
- err = replace_page(vma2, tree_page, page, wprt_pte2);
- if (err) {
- unlock_page(tree_page);
- goto restore_out;
- }
-
- if ((vma2->vm_flags & VM_LOCKED)) {
- munlock_vma_page(tree_page);
- if (!PageMlocked(page)) {
- unlock_page(tree_page);
- lock_page(page);
- mlock_vma_page(page);
- tree_page = page; /* for final unlock */
- }
- }
-
- unlock_page(tree_page);
-
- goto out; /* success */
-
- } else {
- if (tree_rmap_item->hash_max &&
- tree_rmap_item->hash_max == rmap_item->hash_max) {
- err = MERGE_ERR_COLLI_MAX;
- } else if (page_hash(page, hash_strength, 0) ==
- page_hash(tree_page, hash_strength, 0)) {
- inc_rshash_neg(memcmp_cost + hash_strength * 2);
- err = MERGE_ERR_COLLI;
- } else {
- err = MERGE_ERR_CHANGED;
- }
-
- unlock_page(tree_page);
- }
-
-restore_out:
- lock_page(page);
- if (!restore_uksm_page_pte(vma1, get_rmap_addr(rmap_item),
- orig_pte1, wprt_pte1))
- page->mapping = saved_mapping;
-
- unlock_page(page);
-out:
- return err;
-}
-
-static inline int hash_cmp(u32 new_val, u32 node_val)
-{
- if (new_val > node_val)
- return 1;
- else if (new_val < node_val)
- return -1;
- else
- return 0;
-}
-
-static inline u32 rmap_item_hash_max(struct rmap_item *item, u32 hash)
-{
- u32 hash_max = item->hash_max;
-
- if (!hash_max) {
- hash_max = page_hash_max(item->page, hash);
-
- item->hash_max = hash_max;
- }
-
- return hash_max;
-}
-
-
-
-/**
- * stable_tree_search() - search the stable tree for a page
- *
- * @item: the rmap_item we are comparing with
- * @hash: the hash value of this item->page already calculated
- *
- * @return the page we have found, NULL otherwise. The page returned has
- * been gotten.
- */
-static struct page *stable_tree_search(struct rmap_item *item, u32 hash)
-{
- struct rb_node *node = root_stable_treep->rb_node;
- struct tree_node *tree_node;
- unsigned long hash_max;
- struct page *page = item->page;
- struct stable_node *stable_node;
-
- stable_node = page_stable_node(page);
- if (stable_node) {
- /* ksm page forked, that is
- * if (PageKsm(page) && !in_stable_tree(rmap_item))
- * it's actually gotten once outside.
- */
- get_page(page);
- return page;
- }
-
- while (node) {
- int cmp;
-
- tree_node = rb_entry(node, struct tree_node, node);
-
- cmp = hash_cmp(hash, tree_node->hash);
-
- if (cmp < 0)
- node = node->rb_left;
- else if (cmp > 0)
- node = node->rb_right;
- else
- break;
- }
-
- if (!node)
- return NULL;
-
- if (tree_node->count == 1) {
- stable_node = rb_entry(tree_node->sub_root.rb_node,
- struct stable_node, node);
- BUG_ON(!stable_node);
-
- goto get_page_out;
- }
-
- /*
- * ok, we have to search the second
- * level subtree, hash the page to a
- * full strength.
- */
- node = tree_node->sub_root.rb_node;
- BUG_ON(!node);
- hash_max = rmap_item_hash_max(item, hash);
-
- while (node) {
- int cmp;
-
- stable_node = rb_entry(node, struct stable_node, node);
-
- cmp = hash_cmp(hash_max, stable_node->hash_max);
-
- if (cmp < 0)
- node = node->rb_left;
- else if (cmp > 0)
- node = node->rb_right;
- else
- goto get_page_out;
- }
-
- return NULL;
-
-get_page_out:
- page = get_uksm_page(stable_node, 1, 1);
- return page;
-}
-
-static int try_merge_rmap_item(struct rmap_item *item,
- struct page *kpage,
- struct page *tree_page)
-{
- spinlock_t *ptl;
- pte_t *ptep;
- unsigned long addr;
- struct vm_area_struct *vma = item->slot->vma;
-
- addr = get_rmap_addr(item);
- ptep = page_check_address(kpage, vma->vm_mm, addr, &ptl, 0);
- if (!ptep)
- return 0;
-
- if (pte_write(*ptep)) {
- /* has changed, abort! */
- pte_unmap_unlock(ptep, ptl);
- return 0;
- }
-
- get_page(tree_page);
- page_add_anon_rmap(tree_page, vma, addr);
-
- flush_cache_page(vma, addr, pte_pfn(*ptep));
- ptep_clear_flush_notify(vma, addr, ptep);
- set_pte_at_notify(vma->vm_mm, addr, ptep,
- mk_pte(tree_page, vma->vm_page_prot));
-
- page_remove_rmap(kpage);
- put_page(kpage);
-
- pte_unmap_unlock(ptep, ptl);
-
- return 1;
-}
-
-/**
- * try_to_merge_with_stable_page() - when two rmap_items need to be inserted
- * into stable tree, the page was found to be identical to a stable ksm page,
- * this is the last chance we can merge them into one.
- *
- * @item1: the rmap_item holding the page which we wanted to insert
- * into stable tree.
- * @item2: the other rmap_item we found when unstable tree search
- * @oldpage: the page currently mapped by the two rmap_items
- * @tree_page: the page we found identical in stable tree node
- * @success1: return if item1 is successfully merged
- * @success2: return if item2 is successfully merged
- */
-static void try_merge_with_stable(struct rmap_item *item1,
- struct rmap_item *item2,
- struct page **kpage,
- struct page *tree_page,
- int *success1, int *success2)
-{
- struct vm_area_struct *vma1 = item1->slot->vma;
- struct vm_area_struct *vma2 = item2->slot->vma;
- *success1 = 0;
- *success2 = 0;
-
- if (unlikely(*kpage == tree_page)) {
- /* I don't think this can really happen */
- printk(KERN_WARNING "UKSM: unexpected condition detected in "
- "try_merge_with_stable() -- *kpage == tree_page !\n");
- *success1 = 1;
- *success2 = 1;
- return;
- }
-
- if (!PageAnon(*kpage) || !PageKsm(*kpage))
- goto failed;
-
- if (!trylock_page(tree_page))
- goto failed;
-
- /* If the oldpage is still ksm and still pointed
- * to in the right place, and still write protected,
- * we are confident it's not changed, no need to
- * memcmp anymore.
- * be ware, we cannot take nested pte locks,
- * deadlock risk.
- */
- if (!try_merge_rmap_item(item1, *kpage, tree_page))
- goto unlock_failed;
-
- /* ok, then vma2, remind that pte1 already set */
- if (!try_merge_rmap_item(item2, *kpage, tree_page))
- goto success_1;
-
- *success2 = 1;
-success_1:
- *success1 = 1;
-
-
- if ((*success1 && vma1->vm_flags & VM_LOCKED) ||
- (*success2 && vma2->vm_flags & VM_LOCKED)) {
- munlock_vma_page(*kpage);
- if (!PageMlocked(tree_page))
- mlock_vma_page(tree_page);
- }
-
- /*
- * We do not need oldpage any more in the caller, so can break the lock
- * now.
- */
- unlock_page(*kpage);
- *kpage = tree_page; /* Get unlocked outside. */
- return;
-
-unlock_failed:
- unlock_page(tree_page);
-failed:
- return;
-}
-
-static inline void stable_node_hash_max(struct stable_node *node,
- struct page *page, u32 hash)
-{
- u32 hash_max = node->hash_max;
-
- if (!hash_max) {
- hash_max = page_hash_max(page, hash);
- node->hash_max = hash_max;
- }
-}
-
-static inline
-struct stable_node *new_stable_node(struct tree_node *tree_node,
- struct page *kpage, u32 hash_max)
-{
- struct stable_node *new_stable_node;
-
- new_stable_node = alloc_stable_node();
- if (!new_stable_node)
- return NULL;
-
- new_stable_node->kpfn = page_to_pfn(kpage);
- new_stable_node->hash_max = hash_max;
- new_stable_node->tree_node = tree_node;
- set_page_stable_node(kpage, new_stable_node);
-
- return new_stable_node;
-}
-
-static inline
-struct stable_node *first_level_insert(struct tree_node *tree_node,
- struct rmap_item *rmap_item,
- struct rmap_item *tree_rmap_item,
- struct page **kpage, u32 hash,
- int *success1, int *success2)
-{
- int cmp;
- struct page *tree_page;
- u32 hash_max = 0;
- struct stable_node *stable_node, *new_snode;
- struct rb_node *parent = NULL, **new;
-
- /* this tree node contains no sub-tree yet */
- stable_node = rb_entry(tree_node->sub_root.rb_node,
- struct stable_node, node);
-
- tree_page = get_uksm_page(stable_node, 1, 0);
- if (tree_page) {
- cmp = memcmp_pages(*kpage, tree_page, 1);
- if (!cmp) {
- try_merge_with_stable(rmap_item, tree_rmap_item, kpage,
- tree_page, success1, success2);
- put_page(tree_page);
- if (!*success1 && !*success2)
- goto failed;
-
- return stable_node;
-
- } else {
- /*
- * collision in first level try to create a subtree.
- * A new node need to be created.
- */
- put_page(tree_page);
-
- stable_node_hash_max(stable_node, tree_page,
- tree_node->hash);
- hash_max = rmap_item_hash_max(rmap_item, hash);
- cmp = hash_cmp(hash_max, stable_node->hash_max);
-
- parent = &stable_node->node;
- if (cmp < 0) {
- new = &parent->rb_left;
- } else if (cmp > 0) {
- new = &parent->rb_right;
- } else {
- goto failed;
- }
- }
-
- } else {
- /* the only stable_node deleted, we reuse its tree_node.
- */
- parent = NULL;
- new = &tree_node->sub_root.rb_node;
- }
-
- new_snode = new_stable_node(tree_node, *kpage, hash_max);
- if (!new_snode)
- goto failed;
-
- rb_link_node(&new_snode->node, parent, new);
- rb_insert_color(&new_snode->node, &tree_node->sub_root);
- tree_node->count++;
- *success1 = *success2 = 1;
-
- return new_snode;
-
-failed:
- return NULL;
-}
-
-static inline
-struct stable_node *stable_subtree_insert(struct tree_node *tree_node,
- struct rmap_item *rmap_item,
- struct rmap_item *tree_rmap_item,
- struct page **kpage, u32 hash,
- int *success1, int *success2)
-{
- struct page *tree_page;
- u32 hash_max;
- struct stable_node *stable_node, *new_snode;
- struct rb_node *parent, **new;
-
-research:
- parent = NULL;
- new = &tree_node->sub_root.rb_node;
- BUG_ON(!*new);
- hash_max = rmap_item_hash_max(rmap_item, hash);
- while (*new) {
- int cmp;
-
- stable_node = rb_entry(*new, struct stable_node, node);
-
- cmp = hash_cmp(hash_max, stable_node->hash_max);
-
- if (cmp < 0) {
- parent = *new;
- new = &parent->rb_left;
- } else if (cmp > 0) {
- parent = *new;
- new = &parent->rb_right;
- } else {
- tree_page = get_uksm_page(stable_node, 1, 0);
- if (tree_page) {
- cmp = memcmp_pages(*kpage, tree_page, 1);
- if (!cmp) {
- try_merge_with_stable(rmap_item,
- tree_rmap_item, kpage,
- tree_page, success1, success2);
-
- put_page(tree_page);
- if (!*success1 && !*success2)
- goto failed;
- /*
- * successfully merged with a stable
- * node
- */
- return stable_node;
- } else {
- put_page(tree_page);
- goto failed;
- }
- } else {
- /*
- * stable node may be deleted,
- * and subtree maybe
- * restructed, cannot
- * continue, research it.
- */
- if (tree_node->count) {
- goto research;
- } else {
- /* reuse the tree node*/
- parent = NULL;
- new = &tree_node->sub_root.rb_node;
- }
- }
- }
- }
-
- new_snode = new_stable_node(tree_node, *kpage, hash_max);
- if (!new_snode)
- goto failed;
-
- rb_link_node(&new_snode->node, parent, new);
- rb_insert_color(&new_snode->node, &tree_node->sub_root);
- tree_node->count++;
- *success1 = *success2 = 1;
-
- return new_snode;
-
-failed:
- return NULL;
-}
-
-
-/**
- * stable_tree_insert() - try to insert a merged page in unstable tree to
- * the stable tree
- *
- * @kpage: the page need to be inserted
- * @hash: the current hash of this page
- * @rmap_item: the rmap_item being scanned
- * @tree_rmap_item: the rmap_item found on unstable tree
- * @success1: return if rmap_item is merged
- * @success2: return if tree_rmap_item is merged
- *
- * @return the stable_node on stable tree if at least one
- * rmap_item is inserted into stable tree, NULL
- * otherwise.
- */
-static struct stable_node *
-stable_tree_insert(struct page **kpage, u32 hash,
- struct rmap_item *rmap_item,
- struct rmap_item *tree_rmap_item,
- int *success1, int *success2)
-{
- struct rb_node **new = &root_stable_treep->rb_node;
- struct rb_node *parent = NULL;
- struct stable_node *stable_node;
- struct tree_node *tree_node;
- u32 hash_max = 0;
-
- *success1 = *success2 = 0;
-
- while (*new) {
- int cmp;
-
- tree_node = rb_entry(*new, struct tree_node, node);
-
- cmp = hash_cmp(hash, tree_node->hash);
-
- if (cmp < 0) {
- parent = *new;
- new = &parent->rb_left;
- } else if (cmp > 0) {
- parent = *new;
- new = &parent->rb_right;
- } else
- break;
- }
-
- if (*new) {
- if (tree_node->count == 1) {
- stable_node = first_level_insert(tree_node, rmap_item,
- tree_rmap_item, kpage,
- hash, success1, success2);
- } else {
- stable_node = stable_subtree_insert(tree_node,
- rmap_item, tree_rmap_item, kpage,
- hash, success1, success2);
- }
- } else {
-
- /* no tree node found */
- tree_node = alloc_tree_node(stable_tree_node_listp);
- if (!tree_node) {
- stable_node = NULL;
- goto out;
- }
-
- stable_node = new_stable_node(tree_node, *kpage, hash_max);
- if (!stable_node) {
- free_tree_node(tree_node);
- goto out;
- }
-
- tree_node->hash = hash;
- rb_link_node(&tree_node->node, parent, new);
- rb_insert_color(&tree_node->node, root_stable_treep);
- parent = NULL;
- new = &tree_node->sub_root.rb_node;
-
- rb_link_node(&stable_node->node, parent, new);
- rb_insert_color(&stable_node->node, &tree_node->sub_root);
- tree_node->count++;
- *success1 = *success2 = 1;
- }
-
-out:
- return stable_node;
-}
-
-
-/**
- * get_tree_rmap_item_page() - try to get the page and lock the mmap_sem
- *
- * @return 0 on success, -EBUSY if unable to lock the mmap_sem,
- * -EINVAL if the page mapping has been changed.
- */
-static inline int get_tree_rmap_item_page(struct rmap_item *tree_rmap_item)
-{
- int err;
-
- err = get_mergeable_page_lock_mmap(tree_rmap_item);
-
- if (err == -EINVAL) {
- /* its page map has been changed, remove it */
- remove_rmap_item_from_tree(tree_rmap_item);
- }
-
- /* The page is gotten and mmap_sem is locked now. */
- return err;
-}
-
-
-/**
- * unstable_tree_search_insert() - search an unstable tree rmap_item with the
- * same hash value. Get its page and trylock the mmap_sem
- */
-static inline
-struct rmap_item *unstable_tree_search_insert(struct rmap_item *rmap_item,
- u32 hash)
-
-{
- struct rb_node **new = &root_unstable_tree.rb_node;
- struct rb_node *parent = NULL;
- struct tree_node *tree_node;
- u32 hash_max;
- struct rmap_item *tree_rmap_item;
-
- while (*new) {
- int cmp;
-
- tree_node = rb_entry(*new, struct tree_node, node);
-
- cmp = hash_cmp(hash, tree_node->hash);
-
- if (cmp < 0) {
- parent = *new;
- new = &parent->rb_left;
- } else if (cmp > 0) {
- parent = *new;
- new = &parent->rb_right;
- } else
- break;
- }
-
- if (*new) {
- /* got the tree_node */
- if (tree_node->count == 1) {
- tree_rmap_item = rb_entry(tree_node->sub_root.rb_node,
- struct rmap_item, node);
- BUG_ON(!tree_rmap_item);
-
- goto get_page_out;
- }
-
- /* well, search the collision subtree */
- new = &tree_node->sub_root.rb_node;
- BUG_ON(!*new);
- hash_max = rmap_item_hash_max(rmap_item, hash);
-
- while (*new) {
- int cmp;
-
- tree_rmap_item = rb_entry(*new, struct rmap_item,
- node);
-
- cmp = hash_cmp(hash_max, tree_rmap_item->hash_max);
- parent = *new;
- if (cmp < 0)
- new = &parent->rb_left;
- else if (cmp > 0)
- new = &parent->rb_right;
- else
- goto get_page_out;
- }
- } else {
- /* alloc a new tree_node */
- tree_node = alloc_tree_node(&unstable_tree_node_list);
- if (!tree_node)
- return NULL;
-
- tree_node->hash = hash;
- rb_link_node(&tree_node->node, parent, new);
- rb_insert_color(&tree_node->node, &root_unstable_tree);
- parent = NULL;
- new = &tree_node->sub_root.rb_node;
- }
-
- /* did not found even in sub-tree */
- rmap_item->tree_node = tree_node;
- rmap_item->address |= UNSTABLE_FLAG;
- rmap_item->hash_round = uksm_hash_round;
- rb_link_node(&rmap_item->node, parent, new);
- rb_insert_color(&rmap_item->node, &tree_node->sub_root);
-
- uksm_pages_unshared++;
- return NULL;
-
-get_page_out:
- if (tree_rmap_item->page == rmap_item->page)
- return NULL;
-
- if (get_tree_rmap_item_page(tree_rmap_item))
- return NULL;
-
- return tree_rmap_item;
-}
-
-static void hold_anon_vma(struct rmap_item *rmap_item,
- struct anon_vma *anon_vma)
-{
- rmap_item->anon_vma = anon_vma;
- get_anon_vma(anon_vma);
-}
-
-
-/**
- * stable_tree_append() - append a rmap_item to a stable node. Deduplication
- * ratio statistics is done in this function.
- *
- */
-static void stable_tree_append(struct rmap_item *rmap_item,
- struct stable_node *stable_node, int logdedup)
-{
- struct node_vma *node_vma = NULL, *new_node_vma, *node_vma_cont = NULL;
- unsigned long key = (unsigned long)rmap_item->slot;
- unsigned long factor = rmap_item->slot->rung->step;
-
- BUG_ON(!stable_node);
- rmap_item->address |= STABLE_FLAG;
-
- if (hlist_empty(&stable_node->hlist)) {
- uksm_pages_shared++;
- goto node_vma_new;
- } else {
- uksm_pages_sharing++;
- }
-
- hlist_for_each_entry(node_vma, &stable_node->hlist, hlist) {
- if (node_vma->key >= key)
- break;
-
- if (logdedup) {
- node_vma->slot->pages_bemerged += factor;
- if (list_empty(&node_vma->slot->dedup_list))
- list_add(&node_vma->slot->dedup_list,
- &vma_slot_dedup);
- }
- }
-
- if (node_vma) {
- if (node_vma->key == key) {
- node_vma_cont = hlist_entry_safe(node_vma->hlist.next, struct node_vma, hlist);
- goto node_vma_ok;
- } else if (node_vma->key > key) {
- node_vma_cont = node_vma;
- }
- }
-
-node_vma_new:
- /* no same vma already in node, alloc a new node_vma */
- new_node_vma = alloc_node_vma();
- BUG_ON(!new_node_vma);
- new_node_vma->head = stable_node;
- new_node_vma->slot = rmap_item->slot;
-
- if (!node_vma) {
- hlist_add_head(&new_node_vma->hlist, &stable_node->hlist);
- } else if (node_vma->key != key) {
- if (node_vma->key < key)
- hlist_add_behind(&new_node_vma->hlist, &node_vma->hlist);
- else {
- hlist_add_before(&new_node_vma->hlist,
- &node_vma->hlist);
- }
-
- }
- node_vma = new_node_vma;
-
-node_vma_ok: /* ok, ready to add to the list */
- rmap_item->head = node_vma;
- hlist_add_head(&rmap_item->hlist, &node_vma->rmap_hlist);
- hold_anon_vma(rmap_item, rmap_item->slot->vma->anon_vma);
- if (logdedup) {
- rmap_item->slot->pages_merged++;
- if (node_vma_cont) {
- node_vma = node_vma_cont;
- hlist_for_each_entry_continue(node_vma, hlist) {
- node_vma->slot->pages_bemerged += factor;
- if (list_empty(&node_vma->slot->dedup_list))
- list_add(&node_vma->slot->dedup_list,
- &vma_slot_dedup);
- }
- }
- }
-}
-
-/*
- * We use break_ksm to break COW on a ksm page: it's a stripped down
- *
- * if (get_user_pages(current, mm, addr, 1, 1, 1, &page, NULL) == 1)
- * put_page(page);
- *
- * but taking great care only to touch a ksm page, in a VM_MERGEABLE vma,
- * in case the application has unmapped and remapped mm,addr meanwhile.
- * Could a ksm page appear anywhere else? Actually yes, in a VM_PFNMAP
- * mmap of /dev/mem or /dev/kmem, where we would not want to touch it.
- */
-static int break_ksm(struct vm_area_struct *vma, unsigned long addr)
-{
- struct page *page;
- int ret = 0;
-
- do {
- cond_resched();
- page = follow_page(vma, addr, FOLL_GET);
- if (IS_ERR_OR_NULL(page))
- break;
- if (PageKsm(page)) {
- ret = handle_mm_fault(vma->vm_mm, vma, addr,
- FAULT_FLAG_WRITE);
- } else
- ret = VM_FAULT_WRITE;
- put_page(page);
- } while (!(ret & (VM_FAULT_WRITE | VM_FAULT_SIGBUS | VM_FAULT_SIGSEGV | VM_FAULT_OOM)));
- /*
- * We must loop because handle_mm_fault() may back out if there's
- * any difficulty e.g. if pte accessed bit gets updated concurrently.
- *
- * VM_FAULT_WRITE is what we have been hoping for: it indicates that
- * COW has been broken, even if the vma does not permit VM_WRITE;
- * but note that a concurrent fault might break PageKsm for us.
- *
- * VM_FAULT_SIGBUS could occur if we race with truncation of the
- * backing file, which also invalidates anonymous pages: that's
- * okay, that truncation will have unmapped the PageKsm for us.
- *
- * VM_FAULT_OOM: at the time of writing (late July 2009), setting
- * aside mem_cgroup limits, VM_FAULT_OOM would only be set if the
- * current task has TIF_MEMDIE set, and will be OOM killed on return
- * to user; and ksmd, having no mm, would never be chosen for that.
- *
- * But if the mm is in a limited mem_cgroup, then the fault may fail
- * with VM_FAULT_OOM even if the current task is not TIF_MEMDIE; and
- * even ksmd can fail in this way - though it's usually breaking ksm
- * just to undo a merge it made a moment before, so unlikely to oom.
- *
- * That's a pity: we might therefore have more kernel pages allocated
- * than we're counting as nodes in the stable tree; but uksm_do_scan
- * will retry to break_cow on each pass, so should recover the page
- * in due course. The important thing is to not let VM_MERGEABLE
- * be cleared while any such pages might remain in the area.
- */
- return (ret & VM_FAULT_OOM) ? -ENOMEM : 0;
-}
-
-static void break_cow(struct rmap_item *rmap_item)
-{
- struct vm_area_struct *vma = rmap_item->slot->vma;
- struct mm_struct *mm = vma->vm_mm;
- unsigned long addr = get_rmap_addr(rmap_item);
-
- if (uksm_test_exit(mm))
- goto out;
-
- break_ksm(vma, addr);
-out:
- return;
-}
-
-/*
- * Though it's very tempting to unmerge in_stable_tree(rmap_item)s rather
- * than check every pte of a given vma, the locking doesn't quite work for
- * that - an rmap_item is assigned to the stable tree after inserting ksm
- * page and upping mmap_sem. Nor does it fit with the way we skip dup'ing
- * rmap_items from parent to child at fork time (so as not to waste time
- * if exit comes before the next scan reaches it).
- *
- * Similarly, although we'd like to remove rmap_items (so updating counts
- * and freeing memory) when unmerging an area, it's easier to leave that
- * to the next pass of ksmd - consider, for example, how ksmd might be
- * in cmp_and_merge_page on one of the rmap_items we would be removing.
- */
-inline int unmerge_uksm_pages(struct vm_area_struct *vma,
- unsigned long start, unsigned long end)
-{
- unsigned long addr;
- int err = 0;
-
- for (addr = start; addr < end && !err; addr += PAGE_SIZE) {
- if (uksm_test_exit(vma->vm_mm))
- break;
- if (signal_pending(current))
- err = -ERESTARTSYS;
- else
- err = break_ksm(vma, addr);
- }
- return err;
-}
-
-static inline void inc_uksm_pages_scanned(void)
-{
- u64 delta;
-
-
- if (uksm_pages_scanned == U64_MAX) {
- encode_benefit();
-
- delta = uksm_pages_scanned >> pages_scanned_base;
-
- if (CAN_OVERFLOW_U64(pages_scanned_stored, delta)) {
- pages_scanned_stored >>= 1;
- delta >>= 1;
- pages_scanned_base++;
- }
-
- pages_scanned_stored += delta;
-
- uksm_pages_scanned = uksm_pages_scanned_last = 0;
- }
-
- uksm_pages_scanned++;
-}
-
-static inline int find_zero_page_hash(int strength, u32 hash)
-{
- return (zero_hash_table[strength] == hash);
-}
-
-static
-int cmp_and_merge_zero_page(struct vm_area_struct *vma, struct page *page)
-{
- struct page *zero_page = empty_uksm_zero_page;
- struct mm_struct *mm = vma->vm_mm;
- pte_t orig_pte = __pte(0);
- int err = -EFAULT;
-
- if (uksm_test_exit(mm))
- goto out;
-
- if (PageTransCompound(page) && page_trans_compound_anon_split(page))
- goto out;
- BUG_ON(PageTransCompound(page));
-
- if (!PageAnon(page))
- goto out;
-
- if (!trylock_page(page))
- goto out;
-
- if (write_protect_page(vma, page, &orig_pte, 0) == 0) {
- if (is_page_full_zero(page))
- err = replace_page(vma, page, zero_page, orig_pte);
- }
-
- unlock_page(page);
-out:
- return err;
-}
-
-/*
- * cmp_and_merge_page() - first see if page can be merged into the stable
- * tree; if not, compare hash to previous and if it's the same, see if page
- * can be inserted into the unstable tree, or merged with a page already there
- * and both transferred to the stable tree.
- *
- * @page: the page that we are searching identical page to.
- * @rmap_item: the reverse mapping into the virtual address of this page
- */
-static void cmp_and_merge_page(struct rmap_item *rmap_item, u32 hash)
-{
- struct rmap_item *tree_rmap_item;
- struct page *page;
- struct page *kpage = NULL;
- u32 hash_max;
- int err;
- unsigned int success1, success2;
- struct stable_node *snode;
- int cmp;
- struct rb_node *parent = NULL, **new;
-
- remove_rmap_item_from_tree(rmap_item);
- page = rmap_item->page;
-
- /* We first start with searching the page inside the stable tree */
- kpage = stable_tree_search(rmap_item, hash);
- if (kpage) {
- err = try_to_merge_with_uksm_page(rmap_item, kpage,
- hash);
- if (!err) {
- /*
- * The page was successfully merged, add
- * its rmap_item to the stable tree.
- * page lock is needed because it's
- * racing with try_to_unmap_ksm(), etc.
- */
- lock_page(kpage);
- snode = page_stable_node(kpage);
- stable_tree_append(rmap_item, snode, 1);
- unlock_page(kpage);
- put_page(kpage);
- return; /* success */
- }
- put_page(kpage);
-
- /*
- * if it's a collision and it has been search in sub-rbtree
- * (hash_max != 0), we want to abort, because if it is
- * successfully merged in unstable tree, the collision trends to
- * happen again.
- */
- if (err == MERGE_ERR_COLLI && rmap_item->hash_max)
- return;
- }
-
- tree_rmap_item =
- unstable_tree_search_insert(rmap_item, hash);
- if (tree_rmap_item) {
- err = try_to_merge_two_pages(rmap_item, tree_rmap_item, hash);
- /*
- * As soon as we merge this page, we want to remove the
- * rmap_item of the page we have merged with from the unstable
- * tree, and insert it instead as new node in the stable tree.
- */
- if (!err) {
- kpage = page;
- remove_rmap_item_from_tree(tree_rmap_item);
- lock_page(kpage);
- snode = stable_tree_insert(&kpage, hash,
- rmap_item, tree_rmap_item,
- &success1, &success2);
-
- /*
- * Do not log dedup for tree item, it's not counted as
- * scanned in this round.
- */
- if (success2)
- stable_tree_append(tree_rmap_item, snode, 0);
-
- /*
- * The order of these two stable append is important:
- * we are scanning rmap_item.
- */
- if (success1)
- stable_tree_append(rmap_item, snode, 1);
-
- /*
- * The original kpage may be unlocked inside
- * stable_tree_insert() already. This page
- * should be unlocked before doing
- * break_cow().
- */
- unlock_page(kpage);
-
- if (!success1)
- break_cow(rmap_item);
-
- if (!success2)
- break_cow(tree_rmap_item);
-
- } else if (err == MERGE_ERR_COLLI) {
- BUG_ON(tree_rmap_item->tree_node->count > 1);
-
- rmap_item_hash_max(tree_rmap_item,
- tree_rmap_item->tree_node->hash);
-
- hash_max = rmap_item_hash_max(rmap_item, hash);
- cmp = hash_cmp(hash_max, tree_rmap_item->hash_max);
- parent = &tree_rmap_item->node;
- if (cmp < 0)
- new = &parent->rb_left;
- else if (cmp > 0)
- new = &parent->rb_right;
- else
- goto put_up_out;
-
- rmap_item->tree_node = tree_rmap_item->tree_node;
- rmap_item->address |= UNSTABLE_FLAG;
- rmap_item->hash_round = uksm_hash_round;
- rb_link_node(&rmap_item->node, parent, new);
- rb_insert_color(&rmap_item->node,
- &tree_rmap_item->tree_node->sub_root);
- rmap_item->tree_node->count++;
- } else {
- /*
- * either one of the page has changed or they collide
- * at the max hash, we consider them as ill items.
- */
- remove_rmap_item_from_tree(tree_rmap_item);
- }
-put_up_out:
- put_page(tree_rmap_item->page);
- up_read(&tree_rmap_item->slot->vma->vm_mm->mmap_sem);
- }
-}
-
-
-
-
-static inline unsigned long get_pool_index(struct vma_slot *slot,
- unsigned long index)
-{
- unsigned long pool_index;
-
- pool_index = (sizeof(struct rmap_list_entry *) * index) >> PAGE_SHIFT;
- if (pool_index >= slot->pool_size)
- BUG();
- return pool_index;
-}
-
-static inline unsigned long index_page_offset(unsigned long index)
-{
- return offset_in_page(sizeof(struct rmap_list_entry *) * index);
-}
-
-static inline
-struct rmap_list_entry *get_rmap_list_entry(struct vma_slot *slot,
- unsigned long index, int need_alloc)
-{
- unsigned long pool_index;
- struct page *page;
- void *addr;
-
-
- pool_index = get_pool_index(slot, index);
- if (!slot->rmap_list_pool[pool_index]) {
- if (!need_alloc)
- return NULL;
-
- page = alloc_page(GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN);
- if (!page)
- return NULL;
-
- slot->rmap_list_pool[pool_index] = page;
- }
-
- addr = kmap(slot->rmap_list_pool[pool_index]);
- addr += index_page_offset(index);
-
- return addr;
-}
-
-static inline void put_rmap_list_entry(struct vma_slot *slot,
- unsigned long index)
-{
- unsigned long pool_index;
-
- pool_index = get_pool_index(slot, index);
- BUG_ON(!slot->rmap_list_pool[pool_index]);
- kunmap(slot->rmap_list_pool[pool_index]);
-}
-
-static inline int entry_is_new(struct rmap_list_entry *entry)
-{
- return !entry->item;
-}
-
-static inline unsigned long get_index_orig_addr(struct vma_slot *slot,
- unsigned long index)
-{
- return slot->vma->vm_start + (index << PAGE_SHIFT);
-}
-
-static inline unsigned long get_entry_address(struct rmap_list_entry *entry)
-{
- unsigned long addr;
-
- if (is_addr(entry->addr))
- addr = get_clean_addr(entry->addr);
- else if (entry->item)
- addr = get_rmap_addr(entry->item);
- else
- BUG();
-
- return addr;
-}
-
-static inline struct rmap_item *get_entry_item(struct rmap_list_entry *entry)
-{
- if (is_addr(entry->addr))
- return NULL;
-
- return entry->item;
-}
-
-static inline void inc_rmap_list_pool_count(struct vma_slot *slot,
- unsigned long index)
-{
- unsigned long pool_index;
-
- pool_index = get_pool_index(slot, index);
- BUG_ON(!slot->rmap_list_pool[pool_index]);
- slot->pool_counts[pool_index]++;
-}
-
-static inline void dec_rmap_list_pool_count(struct vma_slot *slot,
- unsigned long index)
-{
- unsigned long pool_index;
-
- pool_index = get_pool_index(slot, index);
- BUG_ON(!slot->rmap_list_pool[pool_index]);
- BUG_ON(!slot->pool_counts[pool_index]);
- slot->pool_counts[pool_index]--;
-}
-
-static inline int entry_has_rmap(struct rmap_list_entry *entry)
-{
- return !is_addr(entry->addr) && entry->item;
-}
-
-static inline void swap_entries(struct rmap_list_entry *entry1,
- unsigned long index1,
- struct rmap_list_entry *entry2,
- unsigned long index2)
-{
- struct rmap_list_entry tmp;
-
- /* swapping two new entries is meaningless */
- BUG_ON(entry_is_new(entry1) && entry_is_new(entry2));
-
- tmp = *entry1;
- *entry1 = *entry2;
- *entry2 = tmp;
-
- if (entry_has_rmap(entry1))
- entry1->item->entry_index = index1;
-
- if (entry_has_rmap(entry2))
- entry2->item->entry_index = index2;
-
- if (entry_has_rmap(entry1) && !entry_has_rmap(entry2)) {
- inc_rmap_list_pool_count(entry1->item->slot, index1);
- dec_rmap_list_pool_count(entry1->item->slot, index2);
- } else if (!entry_has_rmap(entry1) && entry_has_rmap(entry2)) {
- inc_rmap_list_pool_count(entry2->item->slot, index2);
- dec_rmap_list_pool_count(entry2->item->slot, index1);
- }
-}
-
-static inline void free_entry_item(struct rmap_list_entry *entry)
-{
- unsigned long index;
- struct rmap_item *item;
-
- if (!is_addr(entry->addr)) {
- BUG_ON(!entry->item);
- item = entry->item;
- entry->addr = get_rmap_addr(item);
- set_is_addr(entry->addr);
- index = item->entry_index;
- remove_rmap_item_from_tree(item);
- dec_rmap_list_pool_count(item->slot, index);
- free_rmap_item(item);
- }
-}
-
-static inline int pool_entry_boundary(unsigned long index)
-{
- unsigned long linear_addr;
-
- linear_addr = sizeof(struct rmap_list_entry *) * index;
- return index && !offset_in_page(linear_addr);
-}
-
-static inline void try_free_last_pool(struct vma_slot *slot,
- unsigned long index)
-{
- unsigned long pool_index;
-
- pool_index = get_pool_index(slot, index);
- if (slot->rmap_list_pool[pool_index] &&
- !slot->pool_counts[pool_index]) {
- __free_page(slot->rmap_list_pool[pool_index]);
- slot->rmap_list_pool[pool_index] = NULL;
- slot->flags |= UKSM_SLOT_NEED_SORT;
- }
-
-}
-
-static inline unsigned long vma_item_index(struct vm_area_struct *vma,
- struct rmap_item *item)
-{
- return (get_rmap_addr(item) - vma->vm_start) >> PAGE_SHIFT;
-}
-
-static int within_same_pool(struct vma_slot *slot,
- unsigned long i, unsigned long j)
-{
- unsigned long pool_i, pool_j;
-
- pool_i = get_pool_index(slot, i);
- pool_j = get_pool_index(slot, j);
-
- return (pool_i == pool_j);
-}
-
-static void sort_rmap_entry_list(struct vma_slot *slot)
-{
- unsigned long i, j;
- struct rmap_list_entry *entry, *swap_entry;
-
- entry = get_rmap_list_entry(slot, 0, 0);
- for (i = 0; i < slot->pages; ) {
-
- if (!entry)
- goto skip_whole_pool;
-
- if (entry_is_new(entry))
- goto next_entry;
-
- if (is_addr(entry->addr)) {
- entry->addr = 0;
- goto next_entry;
- }
-
- j = vma_item_index(slot->vma, entry->item);
- if (j == i)
- goto next_entry;
-
- if (within_same_pool(slot, i, j))
- swap_entry = entry + j - i;
- else
- swap_entry = get_rmap_list_entry(slot, j, 1);
-
- swap_entries(entry, i, swap_entry, j);
- if (!within_same_pool(slot, i, j))
- put_rmap_list_entry(slot, j);
- continue;
-
-skip_whole_pool:
- i += PAGE_SIZE / sizeof(*entry);
- if (i < slot->pages)
- entry = get_rmap_list_entry(slot, i, 0);
- continue;
-
-next_entry:
- if (i >= slot->pages - 1 ||
- !within_same_pool(slot, i, i + 1)) {
- put_rmap_list_entry(slot, i);
- if (i + 1 < slot->pages)
- entry = get_rmap_list_entry(slot, i + 1, 0);
- } else
- entry++;
- i++;
- continue;
- }
-
- /* free empty pool entries which contain no rmap_item */
- /* CAN be simplied to based on only pool_counts when bug freed !!!!! */
- for (i = 0; i < slot->pool_size; i++) {
- unsigned char has_rmap;
- void *addr;
-
- if (!slot->rmap_list_pool[i])
- continue;
-
- has_rmap = 0;
- addr = kmap(slot->rmap_list_pool[i]);
- BUG_ON(!addr);
- for (j = 0; j < PAGE_SIZE / sizeof(*entry); j++) {
- entry = (struct rmap_list_entry *)addr + j;
- if (is_addr(entry->addr))
- continue;
- if (!entry->item)
- continue;
- has_rmap = 1;
- }
- kunmap(slot->rmap_list_pool[i]);
- if (!has_rmap) {
- BUG_ON(slot->pool_counts[i]);
- __free_page(slot->rmap_list_pool[i]);
- slot->rmap_list_pool[i] = NULL;
- }
- }
-
- slot->flags &= ~UKSM_SLOT_NEED_SORT;
-}
-
-/*
- * vma_fully_scanned() - if all the pages in this slot have been scanned.
- */
-static inline int vma_fully_scanned(struct vma_slot *slot)
-{
- return slot->pages_scanned == slot->pages;
-}
-
-/**
- * get_next_rmap_item() - Get the next rmap_item in a vma_slot according to
- * its random permutation. This function is embedded with the random
- * permutation index management code.
- */
-static struct rmap_item *get_next_rmap_item(struct vma_slot *slot, u32 *hash)
-{
- unsigned long rand_range, addr, swap_index, scan_index;
- struct rmap_item *item = NULL;
- struct rmap_list_entry *scan_entry, *swap_entry = NULL;
- struct page *page;
-
- scan_index = swap_index = slot->pages_scanned % slot->pages;
-
- if (pool_entry_boundary(scan_index))
- try_free_last_pool(slot, scan_index - 1);
-
- if (vma_fully_scanned(slot)) {
- if (slot->flags & UKSM_SLOT_NEED_SORT)
- slot->flags |= UKSM_SLOT_NEED_RERAND;
- else
- slot->flags &= ~UKSM_SLOT_NEED_RERAND;
- if (slot->flags & UKSM_SLOT_NEED_SORT)
- sort_rmap_entry_list(slot);
- }
-
- scan_entry = get_rmap_list_entry(slot, scan_index, 1);
- if (!scan_entry)
- return NULL;
-
- if (entry_is_new(scan_entry)) {
- scan_entry->addr = get_index_orig_addr(slot, scan_index);
- set_is_addr(scan_entry->addr);
- }
-
- if (slot->flags & UKSM_SLOT_NEED_RERAND) {
- rand_range = slot->pages - scan_index;
- BUG_ON(!rand_range);
- swap_index = scan_index + (prandom_u32() % rand_range);
- }
-
- if (swap_index != scan_index) {
- swap_entry = get_rmap_list_entry(slot, swap_index, 1);
- if (entry_is_new(swap_entry)) {
- swap_entry->addr = get_index_orig_addr(slot,
- swap_index);
- set_is_addr(swap_entry->addr);
- }
- swap_entries(scan_entry, scan_index, swap_entry, swap_index);
- }
-
- addr = get_entry_address(scan_entry);
- item = get_entry_item(scan_entry);
- BUG_ON(addr > slot->vma->vm_end || addr < slot->vma->vm_start);
-
- page = follow_page(slot->vma, addr, FOLL_GET);
- if (IS_ERR_OR_NULL(page))
- goto nopage;
-
- if (!PageAnon(page) && !page_trans_compound_anon(page))
- goto putpage;
-
- /*check is zero_page pfn or uksm_zero_page*/
- if ((page_to_pfn(page) == zero_pfn)
- || (page_to_pfn(page) == uksm_zero_pfn))
- goto putpage;
-
- flush_anon_page(slot->vma, page, addr);
- flush_dcache_page(page);
-
-
- *hash = page_hash(page, hash_strength, 1);
- inc_uksm_pages_scanned();
- /*if the page content all zero, re-map to zero-page*/
- if (find_zero_page_hash(hash_strength, *hash)) {
- if (!cmp_and_merge_zero_page(slot->vma, page)) {
- slot->pages_merged++;
- inc_zone_page_state(page, NR_UKSM_ZERO_PAGES);
- dec_mm_counter(slot->mm, MM_ANONPAGES);
-
- /* For full-zero pages, no need to create rmap item */
- goto putpage;
- } else {
- inc_rshash_neg(memcmp_cost / 2);
- }
- }
-
- if (!item) {
- item = alloc_rmap_item();
- if (item) {
- /* It has already been zeroed */
- item->slot = slot;
- item->address = addr;
- item->entry_index = scan_index;
- scan_entry->item = item;
- inc_rmap_list_pool_count(slot, scan_index);
- } else
- goto putpage;
- }
-
- BUG_ON(item->slot != slot);
- /* the page may have changed */
- item->page = page;
- put_rmap_list_entry(slot, scan_index);
- if (swap_entry)
- put_rmap_list_entry(slot, swap_index);
- return item;
-
-putpage:
- put_page(page);
- page = NULL;
-nopage:
- /* no page, store addr back and free rmap_item if possible */
- free_entry_item(scan_entry);
- put_rmap_list_entry(slot, scan_index);
- if (swap_entry)
- put_rmap_list_entry(slot, swap_index);
- return NULL;
-}
-
-static inline int in_stable_tree(struct rmap_item *rmap_item)
-{
- return rmap_item->address & STABLE_FLAG;
-}
-
-/**
- * scan_vma_one_page() - scan the next page in a vma_slot. Called with
- * mmap_sem locked.
- */
-static noinline void scan_vma_one_page(struct vma_slot *slot)
-{
- u32 hash;
- struct mm_struct *mm;
- struct rmap_item *rmap_item = NULL;
- struct vm_area_struct *vma = slot->vma;
-
- mm = vma->vm_mm;
- BUG_ON(!mm);
- BUG_ON(!slot);
-
- rmap_item = get_next_rmap_item(slot, &hash);
- if (!rmap_item)
- goto out1;
-
- if (PageKsm(rmap_item->page) && in_stable_tree(rmap_item))
- goto out2;
-
- cmp_and_merge_page(rmap_item, hash);
-out2:
- put_page(rmap_item->page);
-out1:
- slot->pages_scanned++;
- if (slot->fully_scanned_round != fully_scanned_round)
- scanned_virtual_pages++;
-
- if (vma_fully_scanned(slot))
- slot->fully_scanned_round = fully_scanned_round;
-}
-
-static inline unsigned long rung_get_pages(struct scan_rung *rung)
-{
- struct slot_tree_node *node;
-
- if (!rung->vma_root.rnode)
- return 0;
-
- node = container_of(rung->vma_root.rnode, struct slot_tree_node, snode);
-
- return node->size;
-}
-
-#define RUNG_SAMPLED_MIN 3
-
-static inline
-void uksm_calc_rung_step(struct scan_rung *rung,
- unsigned long page_time, unsigned long ratio)
-{
- unsigned long sampled, pages;
-
- /* will be fully scanned ? */
- if (!rung->cover_msecs) {
- rung->step = 1;
- return;
- }
-
- sampled = rung->cover_msecs * (NSEC_PER_MSEC / TIME_RATIO_SCALE)
- * ratio / page_time;
-
- /*
- * Before we finsish a scan round and expensive per-round jobs,
- * we need to have a chance to estimate the per page time. So
- * the sampled number can not be too small.
- */
- if (sampled < RUNG_SAMPLED_MIN)
- sampled = RUNG_SAMPLED_MIN;
-
- pages = rung_get_pages(rung);
- if (likely(pages > sampled))
- rung->step = pages / sampled;
- else
- rung->step = 1;
-}
-
-static inline int step_need_recalc(struct scan_rung *rung)
-{
- unsigned long pages, stepmax;
-
- pages = rung_get_pages(rung);
- stepmax = pages / RUNG_SAMPLED_MIN;
-
- return pages && (rung->step > pages ||
- (stepmax && rung->step > stepmax));
-}
-
-static inline
-void reset_current_scan(struct scan_rung *rung, int finished, int step_recalc)
-{
- struct vma_slot *slot;
-
- if (finished)
- rung->flags |= UKSM_RUNG_ROUND_FINISHED;
-
- if (step_recalc || step_need_recalc(rung)) {
- uksm_calc_rung_step(rung, uksm_ema_page_time, rung->cpu_ratio);
- BUG_ON(step_need_recalc(rung));
- }
-
- slot_iter_index = prandom_u32() % rung->step;
- BUG_ON(!rung->vma_root.rnode);
- slot = sradix_tree_next(&rung->vma_root, NULL, 0, slot_iter);
- BUG_ON(!slot);
-
- rung->current_scan = slot;
- rung->current_offset = slot_iter_index;
-}
-
-static inline struct sradix_tree_root *slot_get_root(struct vma_slot *slot)
-{
- return &slot->rung->vma_root;
-}
-
-/*
- * return if resetted.
- */
-static int advance_current_scan(struct scan_rung *rung)
-{
- unsigned short n;
- struct vma_slot *slot, *next = NULL;
-
- BUG_ON(!rung->vma_root.num);
-
- slot = rung->current_scan;
- n = (slot->pages - rung->current_offset) % rung->step;
- slot_iter_index = rung->step - n;
- next = sradix_tree_next(&rung->vma_root, slot->snode,
- slot->sindex, slot_iter);
-
- if (next) {
- rung->current_offset = slot_iter_index;
- rung->current_scan = next;
- return 0;
- } else {
- reset_current_scan(rung, 1, 0);
- return 1;
- }
-}
-
-static inline void rung_rm_slot(struct vma_slot *slot)
-{
- struct scan_rung *rung = slot->rung;
- struct sradix_tree_root *root;
-
- if (rung->current_scan == slot)
- advance_current_scan(rung);
-
- root = slot_get_root(slot);
- sradix_tree_delete_from_leaf(root, slot->snode, slot->sindex);
- slot->snode = NULL;
- if (step_need_recalc(rung)) {
- uksm_calc_rung_step(rung, uksm_ema_page_time, rung->cpu_ratio);
- BUG_ON(step_need_recalc(rung));
- }
-
- /* In case advance_current_scan loop back to this slot again */
- if (rung->vma_root.num && rung->current_scan == slot)
- reset_current_scan(slot->rung, 1, 0);
-}
-
-static inline void rung_add_new_slots(struct scan_rung *rung,
- struct vma_slot **slots, unsigned long num)
-{
- int err;
- struct vma_slot *slot;
- unsigned long i;
- struct sradix_tree_root *root = &rung->vma_root;
-
- err = sradix_tree_enter(root, (void **)slots, num);
- BUG_ON(err);
-
- for (i = 0; i < num; i++) {
- slot = slots[i];
- slot->rung = rung;
- BUG_ON(vma_fully_scanned(slot));
- }
-
- if (rung->vma_root.num == num)
- reset_current_scan(rung, 0, 1);
-}
-
-static inline int rung_add_one_slot(struct scan_rung *rung,
- struct vma_slot *slot)
-{
- int err;
-
- err = sradix_tree_enter(&rung->vma_root, (void **)&slot, 1);
- if (err)
- return err;
-
- slot->rung = rung;
- if (rung->vma_root.num == 1)
- reset_current_scan(rung, 0, 1);
-
- return 0;
-}
-
-/*
- * Return true if the slot is deleted from its rung.
- */
-static inline int vma_rung_enter(struct vma_slot *slot, struct scan_rung *rung)
-{
- struct scan_rung *old_rung = slot->rung;
- int err;
-
- if (old_rung == rung)
- return 0;
-
- rung_rm_slot(slot);
- err = rung_add_one_slot(rung, slot);
- if (err) {
- err = rung_add_one_slot(old_rung, slot);
- WARN_ON(err); /* OOPS, badly OOM, we lost this slot */
- }
-
- return 1;
-}
-
-static inline int vma_rung_up(struct vma_slot *slot)
-{
- struct scan_rung *rung;
-
- rung = slot->rung;
- if (slot->rung != &uksm_scan_ladder[SCAN_LADDER_SIZE-1])
- rung++;
-
- return vma_rung_enter(slot, rung);
-}
-
-static inline int vma_rung_down(struct vma_slot *slot)
-{
- struct scan_rung *rung;
-
- rung = slot->rung;
- if (slot->rung != &uksm_scan_ladder[0])
- rung--;
-
- return vma_rung_enter(slot, rung);
-}
-
-/**
- * cal_dedup_ratio() - Calculate the deduplication ratio for this slot.
- */
-static unsigned long cal_dedup_ratio(struct vma_slot *slot)
-{
- unsigned long ret;
-
- BUG_ON(slot->pages_scanned == slot->last_scanned);
-
- ret = slot->pages_merged;
-
- /* Thrashing area filtering */
- if (ret && uksm_thrash_threshold) {
- if (slot->pages_cowed * 100 / slot->pages_merged
- > uksm_thrash_threshold) {
- ret = 0;
- } else {
- ret = slot->pages_merged - slot->pages_cowed;
- }
- }
-
- return ret;
-}
-
-/**
- * cal_dedup_ratio() - Calculate the deduplication ratio for this slot.
- */
-static unsigned long cal_dedup_ratio_old(struct vma_slot *slot)
-{
- unsigned long ret;
- unsigned long pages_scanned;
-
- pages_scanned = slot->pages_scanned;
- if (!pages_scanned) {
- if (uksm_thrash_threshold)
- return 0;
- else
- pages_scanned = slot->pages_scanned;
- }
-
- ret = slot->pages_bemerged * 100 / pages_scanned;
-
- /* Thrashing area filtering */
- if (ret && uksm_thrash_threshold) {
- if (slot->pages_cowed * 100 / slot->pages_bemerged
- > uksm_thrash_threshold) {
- ret = 0;
- } else {
- ret = slot->pages_bemerged - slot->pages_cowed;
- }
- }
-
- return ret;
-}
-
-/**
- * stable_node_reinsert() - When the hash_strength has been adjusted, the
- * stable tree need to be restructured, this is the function re-inserting the
- * stable node.
- */
-static inline void stable_node_reinsert(struct stable_node *new_node,
- struct page *page,
- struct rb_root *root_treep,
- struct list_head *tree_node_listp,
- u32 hash)
-{
- struct rb_node **new = &root_treep->rb_node;
- struct rb_node *parent = NULL;
- struct stable_node *stable_node;
- struct tree_node *tree_node;
- struct page *tree_page;
- int cmp;
-
- while (*new) {
- int cmp;
-
- tree_node = rb_entry(*new, struct tree_node, node);
-
- cmp = hash_cmp(hash, tree_node->hash);
-
- if (cmp < 0) {
- parent = *new;
- new = &parent->rb_left;
- } else if (cmp > 0) {
- parent = *new;
- new = &parent->rb_right;
- } else
- break;
- }
-
- if (*new) {
- /* find a stable tree node with same first level hash value */
- stable_node_hash_max(new_node, page, hash);
- if (tree_node->count == 1) {
- stable_node = rb_entry(tree_node->sub_root.rb_node,
- struct stable_node, node);
- tree_page = get_uksm_page(stable_node, 1, 0);
- if (tree_page) {
- stable_node_hash_max(stable_node,
- tree_page, hash);
- put_page(tree_page);
-
- /* prepare for stable node insertion */
-
- cmp = hash_cmp(new_node->hash_max,
- stable_node->hash_max);
- parent = &stable_node->node;
- if (cmp < 0)
- new = &parent->rb_left;
- else if (cmp > 0)
- new = &parent->rb_right;
- else
- goto failed;
-
- goto add_node;
- } else {
- /* the only stable_node deleted, the tree node
- * was not deleted.
- */
- goto tree_node_reuse;
- }
- }
-
- /* well, search the collision subtree */
- new = &tree_node->sub_root.rb_node;
- parent = NULL;
- BUG_ON(!*new);
- while (*new) {
- int cmp;
-
- stable_node = rb_entry(*new, struct stable_node, node);
-
- cmp = hash_cmp(new_node->hash_max,
- stable_node->hash_max);
-
- if (cmp < 0) {
- parent = *new;
- new = &parent->rb_left;
- } else if (cmp > 0) {
- parent = *new;
- new = &parent->rb_right;
- } else {
- /* oh, no, still a collision */
- goto failed;
- }
- }
-
- goto add_node;
- }
-
- /* no tree node found */
- tree_node = alloc_tree_node(tree_node_listp);
- if (!tree_node) {
- printk(KERN_ERR "UKSM: memory allocation error!\n");
- goto failed;
- } else {
- tree_node->hash = hash;
- rb_link_node(&tree_node->node, parent, new);
- rb_insert_color(&tree_node->node, root_treep);
-
-tree_node_reuse:
- /* prepare for stable node insertion */
- parent = NULL;
- new = &tree_node->sub_root.rb_node;
- }
-
-add_node:
- rb_link_node(&new_node->node, parent, new);
- rb_insert_color(&new_node->node, &tree_node->sub_root);
- new_node->tree_node = tree_node;
- tree_node->count++;
- return;
-
-failed:
- /* This can only happen when two nodes have collided
- * in two levels.
- */
- new_node->tree_node = NULL;
- return;
-}
-
-static inline void free_all_tree_nodes(struct list_head *list)
-{
- struct tree_node *node, *tmp;
-
- list_for_each_entry_safe(node, tmp, list, all_list) {
- free_tree_node(node);
- }
-}
-
-/**
- * stable_tree_delta_hash() - Delta hash the stable tree from previous hash
- * strength to the current hash_strength. It re-structures the hole tree.
- */
-static inline void stable_tree_delta_hash(u32 prev_hash_strength)
-{
- struct stable_node *node, *tmp;
- struct rb_root *root_new_treep;
- struct list_head *new_tree_node_listp;
-
- stable_tree_index = (stable_tree_index + 1) % 2;
- root_new_treep = &root_stable_tree[stable_tree_index];
- new_tree_node_listp = &stable_tree_node_list[stable_tree_index];
- *root_new_treep = RB_ROOT;
- BUG_ON(!list_empty(new_tree_node_listp));
-
- /*
- * we need to be safe, the node could be removed by get_uksm_page()
- */
- list_for_each_entry_safe(node, tmp, &stable_node_list, all_list) {
- void *addr;
- struct page *node_page;
- u32 hash;
-
- /*
- * We are completely re-structuring the stable nodes to a new
- * stable tree. We don't want to touch the old tree unlinks and
- * old tree_nodes. The old tree_nodes will be freed at once.
- */
- node_page = get_uksm_page(node, 0, 0);
- if (!node_page)
- continue;
-
- if (node->tree_node) {
- hash = node->tree_node->hash;
-
- addr = kmap_atomic(node_page);
-
- hash = delta_hash(addr, prev_hash_strength,
- hash_strength, hash);
- kunmap_atomic(addr);
- } else {
- /*
- *it was not inserted to rbtree due to collision in last
- *round scan.
- */
- hash = page_hash(node_page, hash_strength, 0);
- }
-
- stable_node_reinsert(node, node_page, root_new_treep,
- new_tree_node_listp, hash);
- put_page(node_page);
- }
-
- root_stable_treep = root_new_treep;
- free_all_tree_nodes(stable_tree_node_listp);
- BUG_ON(!list_empty(stable_tree_node_listp));
- stable_tree_node_listp = new_tree_node_listp;
-}
-
-static inline void inc_hash_strength(unsigned long delta)
-{
- hash_strength += 1 << delta;
- if (hash_strength > HASH_STRENGTH_MAX)
- hash_strength = HASH_STRENGTH_MAX;
-}
-
-static inline void dec_hash_strength(unsigned long delta)
-{
- unsigned long change = 1 << delta;
-
- if (hash_strength <= change + 1)
- hash_strength = 1;
- else
- hash_strength -= change;
-}
-
-static inline void inc_hash_strength_delta(void)
-{
- hash_strength_delta++;
- if (hash_strength_delta > HASH_STRENGTH_DELTA_MAX)
- hash_strength_delta = HASH_STRENGTH_DELTA_MAX;
-}
-
-/*
-static inline unsigned long get_current_neg_ratio(void)
-{
- if (!rshash_pos || rshash_neg > rshash_pos)
- return 100;
-
- return div64_u64(100 * rshash_neg , rshash_pos);
-}
-*/
-
-static inline unsigned long get_current_neg_ratio(void)
-{
- u64 pos = benefit.pos;
- u64 neg = benefit.neg;
-
- if (!neg)
- return 0;
-
- if (!pos || neg > pos)
- return 100;
-
- if (neg > div64_u64(U64_MAX, 100))
- pos = div64_u64(pos, 100);
- else
- neg *= 100;
-
- return div64_u64(neg, pos);
-}
-
-static inline unsigned long get_current_benefit(void)
-{
- u64 pos = benefit.pos;
- u64 neg = benefit.neg;
- u64 scanned = benefit.scanned;
-
- if (neg > pos)
- return 0;
-
- return div64_u64((pos - neg), scanned);
-}
-
-static inline int judge_rshash_direction(void)
-{
- u64 current_neg_ratio, stable_benefit;
- u64 current_benefit, delta = 0;
- int ret = STILL;
-
- /* Try to probe a value after the boot, and in case the system
- are still for a long time. */
- if ((fully_scanned_round & 0xFFULL) == 10) {
- ret = OBSCURE;
- goto out;
- }
-
- current_neg_ratio = get_current_neg_ratio();
-
- if (current_neg_ratio == 0) {
- rshash_neg_cont_zero++;
- if (rshash_neg_cont_zero > 2)
- return GO_DOWN;
- else
- return STILL;
- }
- rshash_neg_cont_zero = 0;
-
- if (current_neg_ratio > 90) {
- ret = GO_UP;
- goto out;
- }
-
- current_benefit = get_current_benefit();
- stable_benefit = rshash_state.stable_benefit;
-
- if (!stable_benefit) {
- ret = OBSCURE;
- goto out;
- }
-
- if (current_benefit > stable_benefit)
- delta = current_benefit - stable_benefit;
- else if (current_benefit < stable_benefit)
- delta = stable_benefit - current_benefit;
-
- delta = div64_u64(100 * delta , stable_benefit);
-
- if (delta > 50) {
- rshash_cont_obscure++;
- if (rshash_cont_obscure > 2)
- return OBSCURE;
- else
- return STILL;
- }
-
-out:
- rshash_cont_obscure = 0;
- return ret;
-}
-
-/**
- * rshash_adjust() - The main function to control the random sampling state
- * machine for hash strength adapting.
- *
- * return true if hash_strength has changed.
- */
-static inline int rshash_adjust(void)
-{
- unsigned long prev_hash_strength = hash_strength;
-
- if (!encode_benefit())
- return 0;
-
- switch (rshash_state.state) {
- case RSHASH_STILL:
- switch (judge_rshash_direction()) {
- case GO_UP:
- if (rshash_state.pre_direct == GO_DOWN)
- hash_strength_delta = 0;
-
- inc_hash_strength(hash_strength_delta);
- inc_hash_strength_delta();
- rshash_state.stable_benefit = get_current_benefit();
- rshash_state.pre_direct = GO_UP;
- break;
-
- case GO_DOWN:
- if (rshash_state.pre_direct == GO_UP)
- hash_strength_delta = 0;
-
- dec_hash_strength(hash_strength_delta);
- inc_hash_strength_delta();
- rshash_state.stable_benefit = get_current_benefit();
- rshash_state.pre_direct = GO_DOWN;
- break;
-
- case OBSCURE:
- rshash_state.stable_point = hash_strength;
- rshash_state.turn_point_down = hash_strength;
- rshash_state.turn_point_up = hash_strength;
- rshash_state.turn_benefit_down = get_current_benefit();
- rshash_state.turn_benefit_up = get_current_benefit();
- rshash_state.lookup_window_index = 0;
- rshash_state.state = RSHASH_TRYDOWN;
- dec_hash_strength(hash_strength_delta);
- inc_hash_strength_delta();
- break;
-
- case STILL:
- break;
- default:
- BUG();
- }
- break;
-
- case RSHASH_TRYDOWN:
- if (rshash_state.lookup_window_index++ % 5 == 0)
- rshash_state.below_count = 0;
-
- if (get_current_benefit() < rshash_state.stable_benefit)
- rshash_state.below_count++;
- else if (get_current_benefit() >
- rshash_state.turn_benefit_down) {
- rshash_state.turn_point_down = hash_strength;
- rshash_state.turn_benefit_down = get_current_benefit();
- }
-
- if (rshash_state.below_count >= 3 ||
- judge_rshash_direction() == GO_UP ||
- hash_strength == 1) {
- hash_strength = rshash_state.stable_point;
- hash_strength_delta = 0;
- inc_hash_strength(hash_strength_delta);
- inc_hash_strength_delta();
- rshash_state.lookup_window_index = 0;
- rshash_state.state = RSHASH_TRYUP;
- hash_strength_delta = 0;
- } else {
- dec_hash_strength(hash_strength_delta);
- inc_hash_strength_delta();
- }
- break;
-
- case RSHASH_TRYUP:
- if (rshash_state.lookup_window_index++ % 5 == 0)
- rshash_state.below_count = 0;
-
- if (get_current_benefit() < rshash_state.turn_benefit_down)
- rshash_state.below_count++;
- else if (get_current_benefit() > rshash_state.turn_benefit_up) {
- rshash_state.turn_point_up = hash_strength;
- rshash_state.turn_benefit_up = get_current_benefit();
- }
-
- if (rshash_state.below_count >= 3 ||
- judge_rshash_direction() == GO_DOWN ||
- hash_strength == HASH_STRENGTH_MAX) {
- hash_strength = rshash_state.turn_benefit_up >
- rshash_state.turn_benefit_down ?
- rshash_state.turn_point_up :
- rshash_state.turn_point_down;
-
- rshash_state.state = RSHASH_PRE_STILL;
- } else {
- inc_hash_strength(hash_strength_delta);
- inc_hash_strength_delta();
- }
-
- break;
-
- case RSHASH_NEW:
- case RSHASH_PRE_STILL:
- rshash_state.stable_benefit = get_current_benefit();
- rshash_state.state = RSHASH_STILL;
- hash_strength_delta = 0;
- break;
- default:
- BUG();
- }
-
- /* rshash_neg = rshash_pos = 0; */
- reset_benefit();
-
- if (prev_hash_strength != hash_strength)
- stable_tree_delta_hash(prev_hash_strength);
-
- return prev_hash_strength != hash_strength;
-}
-
-/**
- * round_update_ladder() - The main function to do update of all the
- * adjustments whenever a scan round is finished.
- */
-static noinline void round_update_ladder(void)
-{
- int i;
- unsigned long dedup;
- struct vma_slot *slot, *tmp_slot;
-
- for (i = 0; i < SCAN_LADDER_SIZE; i++) {
- uksm_scan_ladder[i].flags &= ~UKSM_RUNG_ROUND_FINISHED;
- }
-
- list_for_each_entry_safe(slot, tmp_slot, &vma_slot_dedup, dedup_list) {
-
- /* slot may be rung_rm_slot() when mm exits */
- if (slot->snode) {
- dedup = cal_dedup_ratio_old(slot);
- if (dedup && dedup >= uksm_abundant_threshold)
- vma_rung_up(slot);
- }
-
- slot->pages_bemerged = 0;
- slot->pages_cowed = 0;
-
- list_del_init(&slot->dedup_list);
- }
-}
-
-static void uksm_del_vma_slot(struct vma_slot *slot)
-{
- int i, j;
- struct rmap_list_entry *entry;
-
- if (slot->snode) {
- /*
- * In case it just failed when entering the rung, it's not
- * necessary.
- */
- rung_rm_slot(slot);
- }
-
- if (!list_empty(&slot->dedup_list))
- list_del(&slot->dedup_list);
-
- if (!slot->rmap_list_pool || !slot->pool_counts) {
- /* In case it OOMed in uksm_vma_enter() */
- goto out;
- }
-
- for (i = 0; i < slot->pool_size; i++) {
- void *addr;
-
- if (!slot->rmap_list_pool[i])
- continue;
-
- addr = kmap(slot->rmap_list_pool[i]);
- for (j = 0; j < PAGE_SIZE / sizeof(*entry); j++) {
- entry = (struct rmap_list_entry *)addr + j;
- if (is_addr(entry->addr))
- continue;
- if (!entry->item)
- continue;
-
- remove_rmap_item_from_tree(entry->item);
- free_rmap_item(entry->item);
- slot->pool_counts[i]--;
- }
- BUG_ON(slot->pool_counts[i]);
- kunmap(slot->rmap_list_pool[i]);
- __free_page(slot->rmap_list_pool[i]);
- }
- kfree(slot->rmap_list_pool);
- kfree(slot->pool_counts);
-
-out:
- slot->rung = NULL;
- if (slot->flags & UKSM_SLOT_IN_UKSM) {
- BUG_ON(uksm_pages_total < slot->pages);
- uksm_pages_total -= slot->pages;
- }
-
- if (slot->fully_scanned_round == fully_scanned_round)
- scanned_virtual_pages -= slot->pages;
- else
- scanned_virtual_pages -= slot->pages_scanned;
- free_vma_slot(slot);
-}
-
-
-#define SPIN_LOCK_PERIOD 32
-static struct vma_slot *cleanup_slots[SPIN_LOCK_PERIOD];
-static inline void cleanup_vma_slots(void)
-{
- struct vma_slot *slot;
- int i;
-
- i = 0;
- spin_lock(&vma_slot_list_lock);
- while (!list_empty(&vma_slot_del)) {
- slot = list_entry(vma_slot_del.next,
- struct vma_slot, slot_list);
- list_del(&slot->slot_list);
- cleanup_slots[i++] = slot;
- if (i == SPIN_LOCK_PERIOD) {
- spin_unlock(&vma_slot_list_lock);
- while (--i >= 0)
- uksm_del_vma_slot(cleanup_slots[i]);
- i = 0;
- spin_lock(&vma_slot_list_lock);
- }
- }
- spin_unlock(&vma_slot_list_lock);
-
- while (--i >= 0)
- uksm_del_vma_slot(cleanup_slots[i]);
-}
-
-/*
-*expotional moving average formula
-*/
-static inline unsigned long ema(unsigned long curr, unsigned long last_ema)
-{
- /*
- * For a very high burst, even the ema cannot work well, a false very
- * high per-page time estimation can result in feedback in very high
- * overhead of context swith and rung update -- this will then lead
- * to higher per-paper time, this may not converge.
- *
- * Instead, we try to approach this value in a binary manner.
- */
- if (curr > last_ema * 10)
- return last_ema * 2;
-
- return (EMA_ALPHA * curr + (100 - EMA_ALPHA) * last_ema) / 100;
-}
-
-/*
- * convert cpu ratio in 1/TIME_RATIO_SCALE configured by user to
- * nanoseconds based on current uksm_sleep_jiffies.
- */
-static inline unsigned long cpu_ratio_to_nsec(unsigned int ratio)
-{
- return NSEC_PER_USEC * jiffies_to_usecs(uksm_sleep_jiffies) /
- (TIME_RATIO_SCALE - ratio) * ratio;
-}
-
-
-static inline unsigned long rung_real_ratio(int cpu_time_ratio)
-{
- unsigned long ret;
-
- BUG_ON(!cpu_time_ratio);
-
- if (cpu_time_ratio > 0)
- ret = cpu_time_ratio;
- else
- ret = (unsigned long)(-cpu_time_ratio) *
- uksm_max_cpu_percentage / 100UL;
-
- return ret ? ret : 1;
-}
-
-static noinline void uksm_calc_scan_pages(void)
-{
- struct scan_rung *ladder = uksm_scan_ladder;
- unsigned long sleep_usecs, nsecs;
- unsigned long ratio;
- int i;
- unsigned long per_page;
-
- if (uksm_ema_page_time > 100000 ||
- (((unsigned long) uksm_eval_round & (256UL - 1)) == 0UL))
- uksm_ema_page_time = UKSM_PAGE_TIME_DEFAULT;
-
- per_page = uksm_ema_page_time;
- BUG_ON(!per_page);
-
- /*
- * For every 8 eval round, we try to probe a uksm_sleep_jiffies value
- * based on saved user input.
- */
- if (((unsigned long) uksm_eval_round & (8UL - 1)) == 0UL)
- uksm_sleep_jiffies = uksm_sleep_saved;
-
- /* We require a rung scan at least 1 page in a period. */
- nsecs = per_page;
- ratio = rung_real_ratio(ladder[0].cpu_ratio);
- if (cpu_ratio_to_nsec(ratio) < nsecs) {
- sleep_usecs = nsecs * (TIME_RATIO_SCALE - ratio) / ratio
- / NSEC_PER_USEC;
- uksm_sleep_jiffies = usecs_to_jiffies(sleep_usecs) + 1;
- }
-
- for (i = 0; i < SCAN_LADDER_SIZE; i++) {
- ratio = rung_real_ratio(ladder[i].cpu_ratio);
- ladder[i].pages_to_scan = cpu_ratio_to_nsec(ratio) /
- per_page;
- BUG_ON(!ladder[i].pages_to_scan);
- uksm_calc_rung_step(&ladder[i], per_page, ratio);
- }
-}
-
-/*
- * From the scan time of this round (ns) to next expected min sleep time
- * (ms), be careful of the possible overflows. ratio is taken from
- * rung_real_ratio()
- */
-static inline
-unsigned int scan_time_to_sleep(unsigned long long scan_time, unsigned long ratio)
-{
- scan_time >>= 20; /* to msec level now */
- BUG_ON(scan_time > (ULONG_MAX / TIME_RATIO_SCALE));
-
- return (unsigned int) ((unsigned long) scan_time *
- (TIME_RATIO_SCALE - ratio) / ratio);
-}
-
-#define __round_mask(x, y) ((__typeof__(x))((y)-1))
-#define round_up(x, y) ((((x)-1) | __round_mask(x, y))+1)
-
-static void uksm_vma_enter(struct vma_slot **slots, unsigned long num)
-{
- struct scan_rung *rung;
-
- rung = &uksm_scan_ladder[0];
- rung_add_new_slots(rung, slots, num);
-}
-
-static struct vma_slot *batch_slots[SLOT_TREE_NODE_STORE_SIZE];
-
-static void uksm_enter_all_slots(void)
-{
- struct vma_slot *slot;
- unsigned long index;
- struct list_head empty_vma_list;
- int i;
-
- i = 0;
- index = 0;
- INIT_LIST_HEAD(&empty_vma_list);
-
- spin_lock(&vma_slot_list_lock);
- while (!list_empty(&vma_slot_new)) {
- slot = list_entry(vma_slot_new.next,
- struct vma_slot, slot_list);
-
- if (!slot->vma->anon_vma) {
- list_move(&slot->slot_list, &empty_vma_list);
- } else if (vma_can_enter(slot->vma)) {
- batch_slots[index++] = slot;
- list_del_init(&slot->slot_list);
- } else {
- list_move(&slot->slot_list, &vma_slot_noadd);
- }
-
- if (++i == SPIN_LOCK_PERIOD ||
- (index && !(index % SLOT_TREE_NODE_STORE_SIZE))) {
- spin_unlock(&vma_slot_list_lock);
-
- if (index && !(index % SLOT_TREE_NODE_STORE_SIZE)) {
- uksm_vma_enter(batch_slots, index);
- index = 0;
- }
- i = 0;
- cond_resched();
- spin_lock(&vma_slot_list_lock);
- }
- }
-
- list_splice(&empty_vma_list, &vma_slot_new);
-
- spin_unlock(&vma_slot_list_lock);
-
- if (index)
- uksm_vma_enter(batch_slots, index);
-
-}
-
-static inline int rung_round_finished(struct scan_rung *rung)
-{
- return rung->flags & UKSM_RUNG_ROUND_FINISHED;
-}
-
-static inline void judge_slot(struct vma_slot *slot)
-{
- struct scan_rung *rung = slot->rung;
- unsigned long dedup;
- int deleted;
-
- dedup = cal_dedup_ratio(slot);
- if (vma_fully_scanned(slot) && uksm_thrash_threshold)
- deleted = vma_rung_enter(slot, &uksm_scan_ladder[0]);
- else if (dedup && dedup >= uksm_abundant_threshold)
- deleted = vma_rung_up(slot);
- else
- deleted = vma_rung_down(slot);
-
- slot->pages_merged = 0;
- slot->pages_cowed = 0;
-
- if (vma_fully_scanned(slot))
- slot->pages_scanned = 0;
-
- slot->last_scanned = slot->pages_scanned;
-
- /* If its deleted in above, then rung was already advanced. */
- if (!deleted)
- advance_current_scan(rung);
-}
-
-
-static inline int hash_round_finished(void)
-{
- if (scanned_virtual_pages > (uksm_pages_total >> 2)) {
- scanned_virtual_pages = 0;
- if (uksm_pages_scanned)
- fully_scanned_round++;
-
- return 1;
- } else {
- return 0;
- }
-}
-
-#define UKSM_MMSEM_BATCH 5
-#define BUSY_RETRY 100
-
-/**
- * uksm_do_scan() - the main worker function.
- */
-static noinline void uksm_do_scan(void)
-{
- struct vma_slot *slot, *iter;
- struct mm_struct *busy_mm;
- unsigned char round_finished, all_rungs_emtpy;
- int i, err, mmsem_batch;
- unsigned long pcost;
- long long delta_exec;
- unsigned long vpages, max_cpu_ratio;
- unsigned long long start_time, end_time, scan_time;
- unsigned int expected_jiffies;
-
- might_sleep();
-
- vpages = 0;
-
- start_time = task_sched_runtime(current);
- max_cpu_ratio = 0;
- mmsem_batch = 0;
-
- for (i = 0; i < SCAN_LADDER_SIZE;) {
- struct scan_rung *rung = &uksm_scan_ladder[i];
- unsigned long ratio;
- int busy_retry;
-
- if (!rung->pages_to_scan) {
- i++;
- continue;
- }
-
- if (!rung->vma_root.num) {
- rung->pages_to_scan = 0;
- i++;
- continue;
- }
-
- ratio = rung_real_ratio(rung->cpu_ratio);
- if (ratio > max_cpu_ratio)
- max_cpu_ratio = ratio;
-
- busy_retry = BUSY_RETRY;
- /*
- * Do not consider rung_round_finished() here, just used up the
- * rung->pages_to_scan quota.
- */
- while (rung->pages_to_scan && rung->vma_root.num &&
- likely(!freezing(current))) {
- int reset = 0;
-
- slot = rung->current_scan;
-
- BUG_ON(vma_fully_scanned(slot));
-
- if (mmsem_batch) {
- err = 0;
- } else {
- err = try_down_read_slot_mmap_sem(slot);
- }
-
- if (err == -ENOENT) {
-rm_slot:
- rung_rm_slot(slot);
- continue;
- }
-
- busy_mm = slot->mm;
-
- if (err == -EBUSY) {
- /* skip other vmas on the same mm */
- do {
- reset = advance_current_scan(rung);
- iter = rung->current_scan;
- busy_retry--;
- if (iter->vma->vm_mm != busy_mm ||
- !busy_retry || reset)
- break;
- } while (1);
-
- if (iter->vma->vm_mm != busy_mm) {
- continue;
- } else {
- /* scan round finsished */
- break;
- }
- }
-
- BUG_ON(!vma_can_enter(slot->vma));
- if (uksm_test_exit(slot->vma->vm_mm)) {
- mmsem_batch = 0;
- up_read(&slot->vma->vm_mm->mmap_sem);
- goto rm_slot;
- }
-
- if (mmsem_batch)
- mmsem_batch--;
- else
- mmsem_batch = UKSM_MMSEM_BATCH;
-
- /* Ok, we have take the mmap_sem, ready to scan */
- scan_vma_one_page(slot);
- rung->pages_to_scan--;
- vpages++;
-
- if (rung->current_offset + rung->step > slot->pages - 1
- || vma_fully_scanned(slot)) {
- up_read(&slot->vma->vm_mm->mmap_sem);
- judge_slot(slot);
- mmsem_batch = 0;
- } else {
- rung->current_offset += rung->step;
- if (!mmsem_batch)
- up_read(&slot->vma->vm_mm->mmap_sem);
- }
-
- busy_retry = BUSY_RETRY;
- cond_resched();
- }
-
- if (mmsem_batch) {
- up_read(&slot->vma->vm_mm->mmap_sem);
- mmsem_batch = 0;
- }
-
- if (freezing(current))
- break;
-
- cond_resched();
- }
- end_time = task_sched_runtime(current);
- delta_exec = end_time - start_time;
-
- if (freezing(current))
- return;
-
- cleanup_vma_slots();
- uksm_enter_all_slots();
-
- round_finished = 1;
- all_rungs_emtpy = 1;
- for (i = 0; i < SCAN_LADDER_SIZE; i++) {
- struct scan_rung *rung = &uksm_scan_ladder[i];
-
- if (rung->vma_root.num) {
- all_rungs_emtpy = 0;
- if (!rung_round_finished(rung))
- round_finished = 0;
- }
- }
-
- if (all_rungs_emtpy)
- round_finished = 0;
-
- if (round_finished) {
- round_update_ladder();
- uksm_eval_round++;
-
- if (hash_round_finished() && rshash_adjust()) {
- /* Reset the unstable root iff hash strength changed */
- uksm_hash_round++;
- root_unstable_tree = RB_ROOT;
- free_all_tree_nodes(&unstable_tree_node_list);
- }
-
- /*
- * A number of pages can hang around indefinitely on per-cpu
- * pagevecs, raised page count preventing write_protect_page
- * from merging them. Though it doesn't really matter much,
- * it is puzzling to see some stuck in pages_volatile until
- * other activity jostles them out, and they also prevented
- * LTP's KSM test from succeeding deterministically; so drain
- * them here (here rather than on entry to uksm_do_scan(),
- * so we don't IPI too often when pages_to_scan is set low).
- */
- lru_add_drain_all();
- }
-
-
- if (vpages && delta_exec > 0) {
- pcost = (unsigned long) delta_exec / vpages;
- if (likely(uksm_ema_page_time))
- uksm_ema_page_time = ema(pcost, uksm_ema_page_time);
- else
- uksm_ema_page_time = pcost;
- }
-
- uksm_calc_scan_pages();
- uksm_sleep_real = uksm_sleep_jiffies;
- /* in case of radical cpu bursts, apply the upper bound */
- end_time = task_sched_runtime(current);
- if (max_cpu_ratio && end_time > start_time) {
- scan_time = end_time - start_time;
- expected_jiffies = msecs_to_jiffies(
- scan_time_to_sleep(scan_time, max_cpu_ratio));
-
- if (expected_jiffies > uksm_sleep_real)
- uksm_sleep_real = expected_jiffies;
-
- /* We have a 1 second up bound for responsiveness. */
- if (jiffies_to_msecs(uksm_sleep_real) > MSEC_PER_SEC)
- uksm_sleep_real = msecs_to_jiffies(1000);
- }
-
- return;
-}
-
-static int ksmd_should_run(void)
-{
- return uksm_run & UKSM_RUN_MERGE;
-}
-
-static int uksm_scan_thread(void *nothing)
-{
- set_freezable();
- set_user_nice(current, 5);
-
- while (!kthread_should_stop()) {
- mutex_lock(&uksm_thread_mutex);
- if (ksmd_should_run()) {
- uksm_do_scan();
- }
- mutex_unlock(&uksm_thread_mutex);
-
- try_to_freeze();
-
- if (ksmd_should_run()) {
- schedule_timeout_interruptible(uksm_sleep_real);
- uksm_sleep_times++;
- } else {
- wait_event_freezable(uksm_thread_wait,
- ksmd_should_run() || kthread_should_stop());
- }
- }
- return 0;
-}
-
-int rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc)
-{
- struct stable_node *stable_node;
- struct node_vma *node_vma;
- struct rmap_item *rmap_item;
- int ret = SWAP_AGAIN;
- int search_new_forks = 0;
- unsigned long address;
-
- VM_BUG_ON_PAGE(!PageKsm(page), page);
- VM_BUG_ON_PAGE(!PageLocked(page), page);
-
- stable_node = page_stable_node(page);
- if (!stable_node)
- return ret;
-again:
- hlist_for_each_entry(node_vma, &stable_node->hlist, hlist) {
- hlist_for_each_entry(rmap_item, &node_vma->rmap_hlist, hlist) {
- struct anon_vma *anon_vma = rmap_item->anon_vma;
- struct anon_vma_chain *vmac;
- struct vm_area_struct *vma;
-
- anon_vma_lock_read(anon_vma);
- anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root,
- 0, ULONG_MAX) {
- vma = vmac->vma;
- address = get_rmap_addr(rmap_item);
-
- if (address < vma->vm_start ||
- address >= vma->vm_end)
- continue;
-
- if ((rmap_item->slot->vma == vma) ==
- search_new_forks)
- continue;
-
- if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
- continue;
-
- ret = rwc->rmap_one(page, vma, address, rwc->arg);
- if (ret != SWAP_AGAIN) {
- anon_vma_unlock_read(anon_vma);
- goto out;
- }
-
- if (rwc->done && rwc->done(page)) {
- anon_vma_unlock_read(anon_vma);
- goto out;
- }
- }
- anon_vma_unlock_read(anon_vma);
- }
- }
- if (!search_new_forks++)
- goto again;
-out:
- return ret;
-}
-
-#ifdef CONFIG_MIGRATION
-/* Common ksm interface but may be specific to uksm */
-void ksm_migrate_page(struct page *newpage, struct page *oldpage)
-{
- struct stable_node *stable_node;
-
- VM_BUG_ON_PAGE(!PageLocked(oldpage), oldpage);
- VM_BUG_ON_PAGE(!PageLocked(newpage), newpage);
- VM_BUG_ON(newpage->mapping != oldpage->mapping);
-
- stable_node = page_stable_node(newpage);
- if (stable_node) {
- VM_BUG_ON(stable_node->kpfn != page_to_pfn(oldpage));
- stable_node->kpfn = page_to_pfn(newpage);
- }
-}
-#endif /* CONFIG_MIGRATION */
-
-#ifdef CONFIG_MEMORY_HOTREMOVE
-static struct stable_node *uksm_check_stable_tree(unsigned long start_pfn,
- unsigned long end_pfn)
-{
- struct rb_node *node;
-
- for (node = rb_first(root_stable_treep); node; node = rb_next(node)) {
- struct stable_node *stable_node;
-
- stable_node = rb_entry(node, struct stable_node, node);
- if (stable_node->kpfn >= start_pfn &&
- stable_node->kpfn < end_pfn)
- return stable_node;
- }
- return NULL;
-}
-
-static int uksm_memory_callback(struct notifier_block *self,
- unsigned long action, void *arg)
-{
- struct memory_notify *mn = arg;
- struct stable_node *stable_node;
-
- switch (action) {
- case MEM_GOING_OFFLINE:
- /*
- * Keep it very simple for now: just lock out ksmd and
- * MADV_UNMERGEABLE while any memory is going offline.
- * mutex_lock_nested() is necessary because lockdep was alarmed
- * that here we take uksm_thread_mutex inside notifier chain
- * mutex, and later take notifier chain mutex inside
- * uksm_thread_mutex to unlock it. But that's safe because both
- * are inside mem_hotplug_mutex.
- */
- mutex_lock_nested(&uksm_thread_mutex, SINGLE_DEPTH_NESTING);
- break;
-
- case MEM_OFFLINE:
- /*
- * Most of the work is done by page migration; but there might
- * be a few stable_nodes left over, still pointing to struct
- * pages which have been offlined: prune those from the tree.
- */
- while ((stable_node = uksm_check_stable_tree(mn->start_pfn,
- mn->start_pfn + mn->nr_pages)) != NULL)
- remove_node_from_stable_tree(stable_node, 1, 1);
- /* fallthrough */
-
- case MEM_CANCEL_OFFLINE:
- mutex_unlock(&uksm_thread_mutex);
- break;
- }
- return NOTIFY_OK;
-}
-#endif /* CONFIG_MEMORY_HOTREMOVE */
-
-#ifdef CONFIG_SYSFS
-/*
- * This all compiles without CONFIG_SYSFS, but is a waste of space.
- */
-
-#define UKSM_ATTR_RO(_name) \
- static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
-#define UKSM_ATTR(_name) \
- static struct kobj_attribute _name##_attr = \
- __ATTR(_name, 0644, _name##_show, _name##_store)
-
-static ssize_t max_cpu_percentage_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- return sprintf(buf, "%u\n", uksm_max_cpu_percentage);
-}
-
-static ssize_t max_cpu_percentage_store(struct kobject *kobj,
- struct kobj_attribute *attr,
- const char *buf, size_t count)
-{
- unsigned long max_cpu_percentage;
- int err;
-
- err = kstrtoul(buf, 10, &max_cpu_percentage);
- if (err || max_cpu_percentage > 100)
- return -EINVAL;
-
- if (max_cpu_percentage == 100)
- max_cpu_percentage = 99;
- else if (max_cpu_percentage < 10)
- max_cpu_percentage = 10;
-
- uksm_max_cpu_percentage = max_cpu_percentage;
-
- return count;
-}
-UKSM_ATTR(max_cpu_percentage);
-
-static ssize_t sleep_millisecs_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- return sprintf(buf, "%u\n", jiffies_to_msecs(uksm_sleep_jiffies));
-}
-
-static ssize_t sleep_millisecs_store(struct kobject *kobj,
- struct kobj_attribute *attr,
- const char *buf, size_t count)
-{
- unsigned long msecs;
- int err;
-
- err = kstrtoul(buf, 10, &msecs);
- if (err || msecs > MSEC_PER_SEC)
- return -EINVAL;
-
- uksm_sleep_jiffies = msecs_to_jiffies(msecs);
- uksm_sleep_saved = uksm_sleep_jiffies;
-
- return count;
-}
-UKSM_ATTR(sleep_millisecs);
-
-
-static ssize_t cpu_governor_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- int n = sizeof(uksm_cpu_governor_str) / sizeof(char *);
- int i;
-
- buf[0] = '\0';
- for (i = 0; i < n ; i++) {
- if (uksm_cpu_governor == i)
- strcat(buf, "[");
-
- strcat(buf, uksm_cpu_governor_str[i]);
-
- if (uksm_cpu_governor == i)
- strcat(buf, "]");
-
- strcat(buf, " ");
- }
- strcat(buf, "\n");
-
- return strlen(buf);
-}
-
-static inline void init_performance_values(void)
-{
- int i;
- struct scan_rung *rung;
- struct uksm_cpu_preset_s *preset = uksm_cpu_preset + uksm_cpu_governor;
-
-
- for (i = 0; i < SCAN_LADDER_SIZE; i++) {
- rung = uksm_scan_ladder + i;
- rung->cpu_ratio = preset->cpu_ratio[i];
- rung->cover_msecs = preset->cover_msecs[i];
- }
-
- uksm_max_cpu_percentage = preset->max_cpu;
-}
-
-static ssize_t cpu_governor_store(struct kobject *kobj,
- struct kobj_attribute *attr,
- const char *buf, size_t count)
-{
- int n = sizeof(uksm_cpu_governor_str) / sizeof(char *);
-
- for (n--; n >=0 ; n--) {
- if (!strncmp(buf, uksm_cpu_governor_str[n],
- strlen(uksm_cpu_governor_str[n])))
- break;
- }
-
- if (n < 0)
- return -EINVAL;
- else
- uksm_cpu_governor = n;
-
- init_performance_values();
-
- return count;
-}
-UKSM_ATTR(cpu_governor);
-
-static ssize_t run_show(struct kobject *kobj, struct kobj_attribute *attr,
- char *buf)
-{
- return sprintf(buf, "%u\n", uksm_run);
-}
-
-static ssize_t run_store(struct kobject *kobj, struct kobj_attribute *attr,
- const char *buf, size_t count)
-{
- int err;
- unsigned long flags;
-
- err = kstrtoul(buf, 10, &flags);
- if (err || flags > UINT_MAX)
- return -EINVAL;
- if (flags > UKSM_RUN_MERGE)
- return -EINVAL;
-
- mutex_lock(&uksm_thread_mutex);
- if (uksm_run != flags) {
- uksm_run = flags;
- }
- mutex_unlock(&uksm_thread_mutex);
-
- if (flags & UKSM_RUN_MERGE)
- wake_up_interruptible(&uksm_thread_wait);
-
- return count;
-}
-UKSM_ATTR(run);
-
-static ssize_t abundant_threshold_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- return sprintf(buf, "%u\n", uksm_abundant_threshold);
-}
-
-static ssize_t abundant_threshold_store(struct kobject *kobj,
- struct kobj_attribute *attr,
- const char *buf, size_t count)
-{
- int err;
- unsigned long flags;
-
- err = kstrtoul(buf, 10, &flags);
- if (err || flags > 99)
- return -EINVAL;
-
- uksm_abundant_threshold = flags;
-
- return count;
-}
-UKSM_ATTR(abundant_threshold);
-
-static ssize_t thrash_threshold_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- return sprintf(buf, "%u\n", uksm_thrash_threshold);
-}
-
-static ssize_t thrash_threshold_store(struct kobject *kobj,
- struct kobj_attribute *attr,
- const char *buf, size_t count)
-{
- int err;
- unsigned long flags;
-
- err = kstrtoul(buf, 10, &flags);
- if (err || flags > 99)
- return -EINVAL;
-
- uksm_thrash_threshold = flags;
-
- return count;
-}
-UKSM_ATTR(thrash_threshold);
-
-static ssize_t cpu_ratios_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- int i, size;
- struct scan_rung *rung;
- char *p = buf;
-
- for (i = 0; i < SCAN_LADDER_SIZE; i++) {
- rung = &uksm_scan_ladder[i];
-
- if (rung->cpu_ratio > 0)
- size = sprintf(p, "%d ", rung->cpu_ratio);
- else
- size = sprintf(p, "MAX/%d ",
- TIME_RATIO_SCALE / -rung->cpu_ratio);
-
- p += size;
- }
-
- *p++ = '\n';
- *p = '\0';
-
- return p - buf;
-}
-
-static ssize_t cpu_ratios_store(struct kobject *kobj,
- struct kobj_attribute *attr,
- const char *buf, size_t count)
-{
- int i, cpuratios[SCAN_LADDER_SIZE], err;
- unsigned long value;
- struct scan_rung *rung;
- char *p, *end = NULL;
-
- p = kzalloc(count, GFP_KERNEL);
- if (!p)
- return -ENOMEM;
-
- memcpy(p, buf, count);
-
- for (i = 0; i < SCAN_LADDER_SIZE; i++) {
- if (i != SCAN_LADDER_SIZE -1) {
- end = strchr(p, ' ');
- if (!end)
- return -EINVAL;
-
- *end = '\0';
- }
-
- if (strstr(p, "MAX/")) {
- p = strchr(p, '/') + 1;
- err = kstrtoul(p, 10, &value);
- if (err || value > TIME_RATIO_SCALE || !value)
- return -EINVAL;
-
- cpuratios[i] = - (int) (TIME_RATIO_SCALE / value);
- } else {
- err = kstrtoul(p, 10, &value);
- if (err || value > TIME_RATIO_SCALE || !value)
- return -EINVAL;
-
- cpuratios[i] = value;
- }
-
- p = end + 1;
- }
-
- for (i = 0; i < SCAN_LADDER_SIZE; i++) {
- rung = &uksm_scan_ladder[i];
-
- rung->cpu_ratio = cpuratios[i];
- }
-
- return count;
-}
-UKSM_ATTR(cpu_ratios);
-
-static ssize_t eval_intervals_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- int i, size;
- struct scan_rung *rung;
- char *p = buf;
-
- for (i = 0; i < SCAN_LADDER_SIZE; i++) {
- rung = &uksm_scan_ladder[i];
- size = sprintf(p, "%u ", rung->cover_msecs);
- p += size;
- }
-
- *p++ = '\n';
- *p = '\0';
-
- return p - buf;
-}
-
-static ssize_t eval_intervals_store(struct kobject *kobj,
- struct kobj_attribute *attr,
- const char *buf, size_t count)
-{
- int i, err;
- unsigned long values[SCAN_LADDER_SIZE];
- struct scan_rung *rung;
- char *p, *end = NULL;
-
- p = kzalloc(count, GFP_KERNEL);
- if (!p)
- return -ENOMEM;
-
- memcpy(p, buf, count);
-
- for (i = 0; i < SCAN_LADDER_SIZE; i++) {
- if (i != SCAN_LADDER_SIZE -1) {
- end = strchr(p, ' ');
- if (!end)
- return -EINVAL;
-
- *end = '\0';
- }
-
- err = kstrtoul(p, 10, &values[i]);
- if (err)
- return -EINVAL;
-
- p = end + 1;
- }
-
- for (i = 0; i < SCAN_LADDER_SIZE; i++) {
- rung = &uksm_scan_ladder[i];
-
- rung->cover_msecs = values[i];
- }
-
- return count;
-}
-UKSM_ATTR(eval_intervals);
-
-static ssize_t ema_per_page_time_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- return sprintf(buf, "%lu\n", uksm_ema_page_time);
-}
-UKSM_ATTR_RO(ema_per_page_time);
-
-static ssize_t pages_shared_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- return sprintf(buf, "%lu\n", uksm_pages_shared);
-}
-UKSM_ATTR_RO(pages_shared);
-
-static ssize_t pages_sharing_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- return sprintf(buf, "%lu\n", uksm_pages_sharing);
-}
-UKSM_ATTR_RO(pages_sharing);
-
-static ssize_t pages_unshared_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- return sprintf(buf, "%lu\n", uksm_pages_unshared);
-}
-UKSM_ATTR_RO(pages_unshared);
-
-static ssize_t full_scans_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- return sprintf(buf, "%llu\n", fully_scanned_round);
-}
-UKSM_ATTR_RO(full_scans);
-
-static ssize_t pages_scanned_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- unsigned long base = 0;
- u64 delta, ret;
-
- if (pages_scanned_stored) {
- base = pages_scanned_base;
- ret = pages_scanned_stored;
- delta = uksm_pages_scanned >> base;
- if (CAN_OVERFLOW_U64(ret, delta)) {
- ret >>= 1;
- delta >>= 1;
- base++;
- ret += delta;
- }
- } else {
- ret = uksm_pages_scanned;
- }
-
- while (ret > ULONG_MAX) {
- ret >>= 1;
- base++;
- }
-
- if (base)
- return sprintf(buf, "%lu * 2^%lu\n", (unsigned long)ret, base);
- else
- return sprintf(buf, "%lu\n", (unsigned long)ret);
-}
-UKSM_ATTR_RO(pages_scanned);
-
-static ssize_t hash_strength_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- return sprintf(buf, "%lu\n", hash_strength);
-}
-UKSM_ATTR_RO(hash_strength);
-
-static ssize_t sleep_times_show(struct kobject *kobj,
- struct kobj_attribute *attr, char *buf)
-{
- return sprintf(buf, "%llu\n", uksm_sleep_times);
-}
-UKSM_ATTR_RO(sleep_times);
-
-
-static struct attribute *uksm_attrs[] = {
- &max_cpu_percentage_attr.attr,
- &sleep_millisecs_attr.attr,
- &cpu_governor_attr.attr,
- &run_attr.attr,
- &ema_per_page_time_attr.attr,
- &pages_shared_attr.attr,
- &pages_sharing_attr.attr,
- &pages_unshared_attr.attr,
- &full_scans_attr.attr,
- &pages_scanned_attr.attr,
- &hash_strength_attr.attr,
- &sleep_times_attr.attr,
- &thrash_threshold_attr.attr,
- &abundant_threshold_attr.attr,
- &cpu_ratios_attr.attr,
- &eval_intervals_attr.attr,
- NULL,
-};
-
-static struct attribute_group uksm_attr_group = {
- .attrs = uksm_attrs,
- .name = "uksm",
-};
-#endif /* CONFIG_SYSFS */
-
-static inline void init_scan_ladder(void)
-{
- int i;
- struct scan_rung *rung;
-
- for (i = 0; i < SCAN_LADDER_SIZE; i++) {
- rung = uksm_scan_ladder + i;
- slot_tree_init_root(&rung->vma_root);
- }
-
- init_performance_values();
- uksm_calc_scan_pages();
-}
-
-static inline int cal_positive_negative_costs(void)
-{
- struct page *p1, *p2;
- unsigned char *addr1, *addr2;
- unsigned long i, time_start, hash_cost;
- unsigned long loopnum = 0;
-
- /*IMPORTANT: volatile is needed to prevent over-optimization by gcc. */
- volatile u32 hash;
- volatile int ret;
-
- p1 = alloc_page(GFP_KERNEL);
- if (!p1)
- return -ENOMEM;
-
- p2 = alloc_page(GFP_KERNEL);
- if (!p2)
- return -ENOMEM;
-
- addr1 = kmap_atomic(p1);
- addr2 = kmap_atomic(p2);
- memset(addr1, prandom_u32(), PAGE_SIZE);
- memcpy(addr2, addr1, PAGE_SIZE);
-
- /* make sure that the two pages differ in last byte */
- addr2[PAGE_SIZE-1] = ~addr2[PAGE_SIZE-1];
- kunmap_atomic(addr2);
- kunmap_atomic(addr1);
-
- time_start = jiffies;
- while (jiffies - time_start < 100) {
- for (i = 0; i < 100; i++)
- hash = page_hash(p1, HASH_STRENGTH_FULL, 0);
- loopnum += 100;
- }
- hash_cost = (jiffies - time_start);
-
- time_start = jiffies;
- for (i = 0; i < loopnum; i++)
- ret = pages_identical(p1, p2);
- memcmp_cost = HASH_STRENGTH_FULL * (jiffies - time_start);
- memcmp_cost /= hash_cost;
- printk(KERN_INFO "UKSM: relative memcmp_cost = %lu "
- "hash=%u cmp_ret=%d.\n",
- memcmp_cost, hash, ret);
-
- __free_page(p1);
- __free_page(p2);
- return 0;
-}
-
-static int init_zeropage_hash_table(void)
-{
- struct page *page;
- char *addr;
- int i;
-
- page = alloc_page(GFP_KERNEL);
- if (!page)
- return -ENOMEM;
-
- addr = kmap_atomic(page);
- memset(addr, 0, PAGE_SIZE);
- kunmap_atomic(addr);
-
- zero_hash_table = kmalloc(HASH_STRENGTH_MAX * sizeof(u32),
- GFP_KERNEL);
- if (!zero_hash_table)
- return -ENOMEM;
-
- for (i = 0; i < HASH_STRENGTH_MAX; i++)
- zero_hash_table[i] = page_hash(page, i, 0);
-
- __free_page(page);
-
- return 0;
-}
-
-static inline int init_random_sampling(void)
-{
- unsigned long i;
- random_nums = kmalloc(PAGE_SIZE, GFP_KERNEL);
- if (!random_nums)
- return -ENOMEM;
-
- for (i = 0; i < HASH_STRENGTH_FULL; i++)
- random_nums[i] = i;
-
- for (i = 0; i < HASH_STRENGTH_FULL; i++) {
- unsigned long rand_range, swap_index, tmp;
-
- rand_range = HASH_STRENGTH_FULL - i;
- swap_index = i + prandom_u32() % rand_range;
- tmp = random_nums[i];
- random_nums[i] = random_nums[swap_index];
- random_nums[swap_index] = tmp;
- }
-
- rshash_state.state = RSHASH_NEW;
- rshash_state.below_count = 0;
- rshash_state.lookup_window_index = 0;
-
- return cal_positive_negative_costs();
-}
-
-static int __init uksm_slab_init(void)
-{
- rmap_item_cache = UKSM_KMEM_CACHE(rmap_item, 0);
- if (!rmap_item_cache)
- goto out;
-
- stable_node_cache = UKSM_KMEM_CACHE(stable_node, 0);
- if (!stable_node_cache)
- goto out_free1;
-
- node_vma_cache = UKSM_KMEM_CACHE(node_vma, 0);
- if (!node_vma_cache)
- goto out_free2;
-
- vma_slot_cache = UKSM_KMEM_CACHE(vma_slot, 0);
- if (!vma_slot_cache)
- goto out_free3;
-
- tree_node_cache = UKSM_KMEM_CACHE(tree_node, 0);
- if (!tree_node_cache)
- goto out_free4;
-
- return 0;
-
-out_free4:
- kmem_cache_destroy(vma_slot_cache);
-out_free3:
- kmem_cache_destroy(node_vma_cache);
-out_free2:
- kmem_cache_destroy(stable_node_cache);
-out_free1:
- kmem_cache_destroy(rmap_item_cache);
-out:
- return -ENOMEM;
-}
-
-static void __init uksm_slab_free(void)
-{
- kmem_cache_destroy(stable_node_cache);
- kmem_cache_destroy(rmap_item_cache);
- kmem_cache_destroy(node_vma_cache);
- kmem_cache_destroy(vma_slot_cache);
- kmem_cache_destroy(tree_node_cache);
-}
-
-/* Common interface to ksm, different to it. */
-int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
- unsigned long end, int advice, unsigned long *vm_flags)
-{
- int err;
-
- switch (advice) {
- case MADV_MERGEABLE:
- return 0; /* just ignore the advice */
-
- case MADV_UNMERGEABLE:
- if (!(*vm_flags & VM_MERGEABLE))
- return 0; /* just ignore the advice */
-
- if (vma->anon_vma) {
- err = unmerge_uksm_pages(vma, start, end);
- if (err)
- return err;
- }
-
- uksm_remove_vma(vma);
- *vm_flags &= ~VM_MERGEABLE;
- break;
- }
-
- return 0;
-}
-
-/* Common interface to ksm, actually the same. */
-struct page *ksm_might_need_to_copy(struct page *page,
- struct vm_area_struct *vma, unsigned long address)
-{
- struct anon_vma *anon_vma = page_anon_vma(page);
- struct page *new_page;
-
- if (PageKsm(page)) {
- if (page_stable_node(page))
- return page; /* no need to copy it */
- } else if (!anon_vma) {
- return page; /* no need to copy it */
- } else if (anon_vma->root == vma->anon_vma->root &&
- page->index == linear_page_index(vma, address)) {
- return page; /* still no need to copy it */
- }
- if (!PageUptodate(page))
- return page; /* let do_swap_page report the error */
-
- new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
- if (new_page) {
- copy_user_highpage(new_page, page, address, vma);
-
- SetPageDirty(new_page);
- __SetPageUptodate(new_page);
- __set_page_locked(new_page);
- }
-
- return new_page;
-}
-
-static int __init uksm_init(void)
-{
- struct task_struct *uksm_thread;
- int err;
-
- uksm_sleep_jiffies = msecs_to_jiffies(100);
- uksm_sleep_saved = uksm_sleep_jiffies;
-
- slot_tree_init();
- init_scan_ladder();
-
-
- err = init_random_sampling();
- if (err)
- goto out_free2;
-
- err = uksm_slab_init();
- if (err)
- goto out_free1;
-
- err = init_zeropage_hash_table();
- if (err)
- goto out_free0;
-
- uksm_thread = kthread_run(uksm_scan_thread, NULL, "uksmd");
- if (IS_ERR(uksm_thread)) {
- printk(KERN_ERR "uksm: creating kthread failed\n");
- err = PTR_ERR(uksm_thread);
- goto out_free;
- }
-
-#ifdef CONFIG_SYSFS
- err = sysfs_create_group(mm_kobj, &uksm_attr_group);
- if (err) {
- printk(KERN_ERR "uksm: register sysfs failed\n");
- kthread_stop(uksm_thread);
- goto out_free;
- }
-#else
- uksm_run = UKSM_RUN_MERGE; /* no way for user to start it */
-
-#endif /* CONFIG_SYSFS */
-
-#ifdef CONFIG_MEMORY_HOTREMOVE
- /*
- * Choose a high priority since the callback takes uksm_thread_mutex:
- * later callbacks could only be taking locks which nest within that.
- */
- hotplug_memory_notifier(uksm_memory_callback, 100);
-#endif
- return 0;
-
-out_free:
- kfree(zero_hash_table);
-out_free0:
- uksm_slab_free();
-out_free1:
- kfree(random_nums);
-out_free2:
- kfree(uksm_scan_ladder);
- return err;
-}
-
-#ifdef MODULE
-subsys_initcall(ksm_init);
-#else
-late_initcall(uksm_init);
-#endif
-
diff --git a/mm/vmstat.c b/mm/vmstat.c
index c301bd6e0..084c6725b 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -764,9 +764,6 @@ const char * const vmstat_text[] = {
"nr_anon_transparent_hugepages",
"nr_free_cma",
-#ifdef CONFIG_UKSM
- "nr_uksm_zero_pages",
-#endif
/* enum writeback_stat_item counters */
"nr_dirty_threshold",
"nr_dirty_background_threshold",