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| author | Ying Han <yinghan@google.com> | 2010-10-26 14:21:23 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-10-26 16:52:05 -0700 |
| commit | 3d5992d2ac7dc09aed8ab537cba074589f0f0a52 (patch) | |
| tree | 0fbb51026e8aa13ddd7a6516c04471ceb97bc277 /kernel/exit.c | |
| parent | 0f4d208f1975f16f269134cee5f44c1f048581da (diff) | |
| download | lwn-3d5992d2ac7dc09aed8ab537cba074589f0f0a52.tar.gz lwn-3d5992d2ac7dc09aed8ab537cba074589f0f0a52.zip | |
oom: add per-mm oom disable count
It's pointless to kill a task if another thread sharing its mm cannot be
killed to allow future memory freeing. A subsequent patch will prevent
kills in such cases, but first it's necessary to have a way to flag a task
that shares memory with an OOM_DISABLE task that doesn't incur an
additional tasklist scan, which would make select_bad_process() an O(n^2)
function.
This patch adds an atomic counter to struct mm_struct that follows how
many threads attached to it have an oom_score_adj of OOM_SCORE_ADJ_MIN.
They cannot be killed by the kernel, so their memory cannot be freed in
oom conditions.
This only requires task_lock() on the task that we're operating on, it
does not require mm->mmap_sem since task_lock() pins the mm and the
operation is atomic.
[rientjes@google.com: changelog and sys_unshare() code]
[rientjes@google.com: protect oom_disable_count with task_lock in fork]
[rientjes@google.com: use old_mm for oom_disable_count in exec]
Signed-off-by: Ying Han <yinghan@google.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/exit.c')
| -rw-r--r-- | kernel/exit.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index e2bdf37f9fde..894179a32ec1 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -50,6 +50,7 @@ #include <linux/perf_event.h> #include <trace/events/sched.h> #include <linux/hw_breakpoint.h> +#include <linux/oom.h> #include <asm/uaccess.h> #include <asm/unistd.h> @@ -687,6 +688,8 @@ 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); |