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authorDavid Rientjes <rientjes@google.com>2011-10-31 17:07:15 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2011-10-31 17:30:45 -0700
commitc9f01245b6a7d77d17deaa71af10f6aca14fa24e (patch)
tree13ffde591a5bcefba39cb6393f09b27f1ebc1a30 /kernel
parent7b0d44fa49b1dcfdcf4897f12ddd12ddeab1a9d7 (diff)
oom: remove oom_disable_count
This removes mm->oom_disable_count entirely since it's unnecessary and currently buggy. The counter was intended to be per-process but it's currently decremented in the exit path for each thread that exits, causing it to underflow. The count was originally intended to prevent oom killing threads that share memory with threads that cannot be killed since it doesn't lead to future memory freeing. The counter could be fixed to represent all threads sharing the same mm, but it's better to remove the count since: - it is possible that the OOM_DISABLE thread sharing memory with the victim is waiting on that thread to exit and will actually cause future memory freeing, and - there is no guarantee that a thread is disabled from oom killing just because another thread sharing its mm is oom disabled. Signed-off-by: David Rientjes <rientjes@google.com> Reported-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Cc: Ying Han <yinghan@google.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/exit.c2
-rw-r--r--kernel/fork.c10
2 files changed, 1 insertions, 11 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index 2913b3509d4..d0b7d988f87 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -681,8 +681,6 @@ static void exit_mm(struct task_struct * tsk)
enter_lazy_tlb(mm, current);
/* We don't want this task to be frozen prematurely */
clear_freeze_flag(tsk);
- if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
- atomic_dec(&mm->oom_disable_count);
task_unlock(tsk);
mm_update_next_owner(mm);
mmput(mm);
diff --git a/kernel/fork.c b/kernel/fork.c
index 8e6b6f4fb27..70d76191afb 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -501,7 +501,6 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
mm->cached_hole_size = ~0UL;
mm_init_aio(mm);
mm_init_owner(mm, p);
- atomic_set(&mm->oom_disable_count, 0);
if (likely(!mm_alloc_pgd(mm))) {
mm->def_flags = 0;
@@ -816,8 +815,6 @@ good_mm:
/* Initializing for Swap token stuff */
mm->token_priority = 0;
mm->last_interval = 0;
- if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
- atomic_inc(&mm->oom_disable_count);
tsk->mm = mm;
tsk->active_mm = mm;
@@ -1391,13 +1388,8 @@ bad_fork_cleanup_io:
bad_fork_cleanup_namespaces:
exit_task_namespaces(p);
bad_fork_cleanup_mm:
- if (p->mm) {
- task_lock(p);
- if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
- atomic_dec(&p->mm->oom_disable_count);
- task_unlock(p);
+ if (p->mm)
mmput(p->mm);
- }
bad_fork_cleanup_signal:
if (!(clone_flags & CLONE_THREAD))
free_signal_struct(p->signal);