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Diffstat (limited to 'mm/oom_kill.c')
-rw-r--r--mm/oom_kill.c78
1 files changed, 55 insertions, 23 deletions
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 1ecc0bcae..c12680993 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -118,6 +118,15 @@ found:
return t;
}
+/*
+ * order == -1 means the oom kill is required by sysrq, otherwise only
+ * for display purposes.
+ */
+static inline bool is_sysrq_oom(struct oom_control *oc)
+{
+ return oc->order == -1;
+}
+
/* return true if the task is not adequate as candidate victim task. */
static bool oom_unkillable_task(struct task_struct *p,
struct mem_cgroup *memcg, const nodemask_t *nodemask)
@@ -265,7 +274,7 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc,
* Don't allow any other task to have access to the reserves.
*/
if (test_tsk_thread_flag(task, TIF_MEMDIE)) {
- if (oc->order != -1)
+ if (!is_sysrq_oom(oc))
return OOM_SCAN_ABORT;
}
if (!task->mm)
@@ -278,7 +287,7 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc,
if (oom_task_origin(task))
return OOM_SCAN_SELECT;
- if (task_will_free_mem(task) && oc->order != -1)
+ if (task_will_free_mem(task) && !is_sysrq_oom(oc))
return OOM_SCAN_ABORT;
return OOM_SCAN_OK;
@@ -377,13 +386,11 @@ static void dump_tasks(struct mem_cgroup *memcg, const nodemask_t *nodemask)
static void dump_header(struct oom_control *oc, struct task_struct *p,
struct mem_cgroup *memcg)
{
- task_lock(current);
pr_warning("%s invoked oom-killer: gfp_mask=0x%x, order=%d, "
"oom_score_adj=%hd\n",
current->comm, oc->gfp_mask, oc->order,
current->signal->oom_score_adj);
- cpuset_print_task_mems_allowed(current);
- task_unlock(current);
+ cpuset_print_current_mems_allowed();
dump_stack();
if (memcg)
mem_cgroup_print_oom_info(memcg, p);
@@ -476,6 +483,24 @@ void oom_killer_enable(void)
oom_killer_disabled = false;
}
+/*
+ * task->mm can be NULL if the task is the exited group leader. So to
+ * determine whether the task is using a particular mm, we examine all the
+ * task's threads: if one of those is using this mm then this task was also
+ * using it.
+ */
+static bool process_shares_mm(struct task_struct *p, struct mm_struct *mm)
+{
+ struct task_struct *t;
+
+ for_each_thread(p, t) {
+ struct mm_struct *t_mm = READ_ONCE(t->mm);
+ if (t_mm)
+ return t_mm == mm;
+ }
+ return false;
+}
+
#define K(x) ((x) << (PAGE_SHIFT-10))
/*
* Must be called while holding a reference to p, which will be released upon
@@ -509,10 +534,8 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
if (__ratelimit(&oom_rs))
dump_header(oc, p, memcg);
- task_lock(p);
pr_err("%s: Kill process %d (%s) score %u or sacrifice child\n",
message, task_pid_nr(p), p->comm, points);
- task_unlock(p);
/*
* If any of p's children has a different mm and is eligible for kill,
@@ -525,7 +548,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
list_for_each_entry(child, &t->children, sibling) {
unsigned int child_points;
- if (child->mm == p->mm)
+ if (process_shares_mm(child, p->mm))
continue;
/*
* oom_badness() returns 0 if the thread is unkillable
@@ -552,8 +575,15 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
victim = p;
}
- /* mm cannot safely be dereferenced after task_unlock(victim) */
+ /* Get a reference to safely compare mm after task_unlock(victim) */
mm = victim->mm;
+ atomic_inc(&mm->mm_count);
+ /*
+ * We should send SIGKILL before setting TIF_MEMDIE in order to prevent
+ * the OOM victim from depleting the memory reserves from the user
+ * space under its control.
+ */
+ do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true);
mark_oom_victim(victim);
pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
@@ -571,21 +601,23 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
* pending fatal signal.
*/
rcu_read_lock();
- for_each_process(p)
- if (p->mm == mm && !same_thread_group(p, victim) &&
- !(p->flags & PF_KTHREAD)) {
- if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
- continue;
+ for_each_process(p) {
+ if (!process_shares_mm(p, mm))
+ continue;
+ if (same_thread_group(p, victim))
+ continue;
+ if (unlikely(p->flags & PF_KTHREAD))
+ continue;
+ if (is_global_init(p))
+ continue;
+ if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
+ continue;
- task_lock(p); /* Protect ->comm from prctl() */
- pr_err("Kill process %d (%s) sharing same memory\n",
- task_pid_nr(p), p->comm);
- task_unlock(p);
- do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
- }
+ do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
+ }
rcu_read_unlock();
- do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true);
+ mmdrop(mm);
put_task_struct(victim);
}
#undef K
@@ -608,7 +640,7 @@ void check_panic_on_oom(struct oom_control *oc, enum oom_constraint constraint,
return;
}
/* Do not panic for oom kills triggered by sysrq */
- if (oc->order == -1)
+ if (is_sysrq_oom(oc))
return;
dump_header(oc, NULL, memcg);
panic("Out of memory: %s panic_on_oom is enabled\n",
@@ -688,7 +720,7 @@ bool out_of_memory(struct oom_control *oc)
p = select_bad_process(oc, &points, totalpages);
/* Found nothing?!?! Either we hang forever, or we panic. */
- if (!p && oc->order != -1) {
+ if (!p && !is_sysrq_oom(oc)) {
dump_header(oc, NULL, NULL);
panic("Out of memory and no killable processes...\n");
}