From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f70.google.com (mail-wm0-f70.google.com [74.125.82.70]) by kanga.kvack.org (Postfix) with ESMTP id 6C0FE6B0260 for ; Thu, 28 Jul 2016 15:42:45 -0400 (EDT) Received: by mail-wm0-f70.google.com with SMTP id o80so24883800wme.1 for ; Thu, 28 Jul 2016 12:42:45 -0700 (PDT) Received: from mail-wm0-f67.google.com (mail-wm0-f67.google.com. [74.125.82.67]) by mx.google.com with ESMTPS id o2si42947566wmg.89.2016.07.28.12.42.42 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 28 Jul 2016 12:42:42 -0700 (PDT) Received: by mail-wm0-f67.google.com with SMTP id x83so12612550wma.3 for ; Thu, 28 Jul 2016 12:42:42 -0700 (PDT) From: Michal Hocko Subject: [PATCH 02/10] mm,oom_reaper: Do not attempt to reap a task twice. Date: Thu, 28 Jul 2016 21:42:26 +0200 Message-Id: <1469734954-31247-3-git-send-email-mhocko@kernel.org> In-Reply-To: <1469734954-31247-1-git-send-email-mhocko@kernel.org> References: <1469734954-31247-1-git-send-email-mhocko@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Cc: Andrew Morton , Tetsuo Handa , Oleg Nesterov , David Rientjes , Vladimir Davydov , Michal Hocko From: Tetsuo Handa "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. Signed-off-by: Tetsuo Handa Signed-off-by: Michal Hocko --- include/linux/sched.h | 1 - mm/oom_kill.c | 15 +++------------ 2 files changed, 3 insertions(+), 13 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 3568dfca12bb..d9585771dc8b 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -512,7 +512,6 @@ static inline int get_dumpable(struct mm_struct *mm) #define MMF_HAS_UPROBES 19 /* has uprobes */ #define MMF_RECALC_UPROBES 20 /* MMF_HAS_UPROBES can be wrong */ #define MMF_OOM_REAPED 21 /* mm has been already reaped */ -#define MMF_OOM_NOT_REAPABLE 22 /* mm couldn't be reaped */ #define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index f685341bdee2..a8c06883a142 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -567,20 +567,11 @@ 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: -- 2.8.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org