From 8496afaba93ece80a83cbd096f0675a1020ddfc4 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Fri, 7 Oct 2016 16:58:48 -0700 Subject: mm,oom_reaper: do not attempt to reap a task twice "mm, oom_reaper: do not attempt to reap a task twice" tried to give the OOM reaper one more chance to retry using MMF_OOM_NOT_REAPABLE flag. But the usefulness of the flag is rather limited and actually never shown in practice. If the flag is set, it means that the holder of mm->mmap_sem cannot call up_write() due to presumably being blocked at unkillable wait waiting for other thread's memory allocation. But since one of threads sharing that mm will queue that mm immediately via task_will_free_mem() shortcut (otherwise, oom_badness() will select the same mm again due to oom_score_adj value unchanged), retrying MMF_OOM_NOT_REAPABLE mm is unlikely helpful. Let's always set MMF_OOM_REAPED. Link: http://lkml.kernel.org/r/1472119394-11342-3-git-send-email-mhocko@kernel.org Signed-off-by: Tetsuo Handa Signed-off-by: Michal Hocko Cc: Oleg Nesterov Cc: David Rientjes Cc: Vladimir Davydov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/oom_kill.c | 15 +++------------ 1 file changed, 3 insertions(+), 12 deletions(-) (limited to 'mm/oom_kill.c') diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 87fad956c96b..45097f5a8f30 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -578,20 +578,11 @@ static void oom_reap_task(struct task_struct *tsk) if (attempts <= MAX_OOM_REAP_RETRIES) goto done; + /* Ignore this mm because somebody can't call up_write(mmap_sem). */ + set_bit(MMF_OOM_REAPED, &mm->flags); + pr_info("oom_reaper: unable to reap pid:%d (%s)\n", task_pid_nr(tsk), tsk->comm); - - /* - * If we've already tried to reap this task in the past and - * failed it probably doesn't make much sense to try yet again - * so hide the mm from the oom killer so that it can move on - * to another task with a different mm struct. - */ - if (test_and_set_bit(MMF_OOM_NOT_REAPABLE, &mm->flags)) { - pr_info("oom_reaper: giving up pid:%d (%s)\n", - task_pid_nr(tsk), tsk->comm); - set_bit(MMF_OOM_REAPED, &mm->flags); - } debug_show_all_locks(); done: -- cgit v1.2.3