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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-09-08 01:01:14 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-09-08 01:01:14 -0300
commite5fd91f1ef340da553f7a79da9540c3db711c937 (patch)
treeb11842027dc6641da63f4bcc524f8678263304a3 /mm/rmap.c
parent2a9b0348e685a63d97486f6749622b61e9e3292f (diff)
Linux-libre 4.2-gnu
Diffstat (limited to 'mm/rmap.c')
-rw-r--r--mm/rmap.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index f4d9cfdca..45435c8a5 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -30,6 +30,8 @@
* swap_lock (in swap_duplicate, swap_info_get)
* mmlist_lock (in mmput, drain_mmlist and others)
* mapping->private_lock (in __set_page_dirty_buffers)
+ * mem_cgroup_{begin,end}_page_stat (memcg->move_lock)
+ * mapping->tree_lock (widely used)
* inode->i_lock (in set_page_dirty's __mark_inode_dirty)
* bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
* sb_lock (within inode_lock in fs/fs-writeback.c)
@@ -625,7 +627,7 @@ pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
pmd = pmd_offset(pud, address);
/*
- * Some THP functions use the sequence pmdp_clear_flush(), set_pmd_at()
+ * Some THP functions use the sequence pmdp_huge_clear_flush(), set_pmd_at()
* without holding anon_vma lock for write. So when looking for a
* genuine pmde (in which to find pte), test present and !THP together.
*/
@@ -950,7 +952,12 @@ void page_move_anon_rmap(struct page *page,
VM_BUG_ON_PAGE(page->index != linear_page_index(vma, address), page);
anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
- page->mapping = (struct address_space *) anon_vma;
+ /*
+ * Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written
+ * simultaneously, so a concurrent reader (eg page_referenced()'s
+ * PageAnon()) will not see one without the other.
+ */
+ WRITE_ONCE(page->mapping, (struct address_space *) anon_vma);
}
/**