The patch titled
oom: avoid race for oom killed tasks detaching mm prior to exit
has been added to the -mm tree. Its filename is
oom-avoid-race-for-oom-killed-tasks-detaching-mm-prior-to-exit.patch
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------------------------------------------------------
Subject: oom: avoid race for oom killed tasks detaching mm prior to exit
From: David Rientjes <rientjes@xxxxxxxxxx>
Tasks detach its ->mm prior to exiting so it's possible that in progress
oom kills or already exiting tasks may be missed during the oom killer's
tasklist scan. When an eligible task is found with either TIF_MEMDIE or
PF_EXITING set, the oom killer is supposed to be a no-op to avoid
needlessly killing additional tasks. This closes the race between a task
detaching its ->mm and being removed from the tasklist.
Out of memory conditions as the result of memory controllers will
automatically filter tasks that have detached their ->mm (since
task_in_mem_cgroup() will return 0). This is acceptable, however, since
memcg constrained ooms aren't the result of a lack of memory resources but
rather a limit imposed by userspace that requires a task be killed
regardless.
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/oom_kill.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff -puN mm/oom_kill.c~oom-avoid-race-for-oom-killed-tasks-detaching-mm-prior-to-exit mm/oom_kill.c
--- a/mm/oom_kill.c~oom-avoid-race-for-oom-killed-tasks-detaching-mm-prior-to-exit
+++ a/mm/oom_kill.c
@@ -290,12 +290,6 @@ static struct task_struct *select_bad_pr
for_each_process(p) {
unsigned int points;
- /*
- * skip kernel threads and tasks which have already released
- * their mm.
- */
- if (!p->mm)
- continue;
/* skip the init task */
if (is_global_init(p))
continue;
@@ -336,6 +330,12 @@ static struct task_struct *select_bad_pr
*ppoints = 1000;
}
+ /*
+ * skip kernel threads and tasks which have already released
+ * their mm.
+ */
+ if (!p->mm)
+ continue;
if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
continue;
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
linux-next.patch
cpuset-fix-the-problem-that-cpuset_mem_spread_node-returns-an-offline-node.patch
cpuset-alloc-nodemask_t-on-the-heap-rather-than-the-stack.patch
mempolicy-remove-redundant-code.patch
oom-filter-tasks-not-sharing-the-same-cpuset.patch
oom-sacrifice-child-with-highest-badness-score-for-parent.patch
oom-select-task-from-tasklist-for-mempolicy-ooms.patch
oom-remove-special-handling-for-pagefault-ooms.patch
oom-badness-heuristic-rewrite.patch
oom-deprecate-oom_adj-tunable.patch
oom-replace-sysctls-with-quick-mode.patch
oom-avoid-oom-killer-for-lowmem-allocations.patch
oom-remove-unnecessary-code-and-cleanup.patch
oom-default-to-killing-current-for-pagefault-ooms.patch
oom-avoid-race-for-oom-killed-tasks-detaching-mm-prior-to-exit.patch
memcg-oom-wakeup-filter.patch
memcg-oom-wakeup-filter-update.patch
memcg-oom-notifier.patch
memcg-oom-notifier-update.patch
memcg-oom-kill-disable-and-oom-status.patch
memcg-oom-kill-disable-and-oom-status-update.patch
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