From: Michal Hocko <mhocko@suse.cz> To: Johannes Weiner <hannes@cmpxchg.org> Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org>, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, Huang Ying <ying.huang@intel.com>, Andrea Arcangeli <aarcange@redhat.com>, Dave Chinner <david@fromorbit.com>, "Theodore Ts'o" <tytso@mit.edu> Subject: Re: [patch 05/12] mm: oom_kill: generalize OOM progress waitqueue Date: Thu, 26 Mar 2015 14:03:50 +0100 [thread overview] Message-ID: <20150326130350.GH15257@dhcp22.suse.cz> (raw) In-Reply-To: <1427264236-17249-6-git-send-email-hannes@cmpxchg.org> On Wed 25-03-15 02:17:09, Johannes Weiner wrote: > It turns out that the mechanism to wait for exiting OOM victims is > less generic than it looks: it won't issue wakeups unless the OOM > killer is disabled. > > The reason this check was added was the thought that, since only the > OOM disabling code would wait on this queue, wakeup operations could > be saved when that specific consumer is known to be absent. > > However, this is quite the handgrenade. Later attempts to reuse the > waitqueue for other purposes will lead to completely unexpected bugs > and the failure mode will appear seemingly illogical. Generally, > providers shouldn't make unnecessary assumptions about consumers. > > This could have been replaced with waitqueue_active(), but it only > saves a few instructions in one of the coldest paths in the kernel. > Simply remove it. > > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> > --- > mm/oom_kill.c | 6 +----- > 1 file changed, 1 insertion(+), 5 deletions(-) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 88aa9ba40fa5..d3490b019d46 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -437,11 +437,7 @@ void exit_oom_victim(void) > { > clear_thread_flag(TIF_MEMDIE); > > - /* > - * There is no need to signal the lasst oom_victim if there > - * is nobody who cares. > - */ > - if (!atomic_dec_return(&oom_victims) && oom_killer_disabled) > + if (!atomic_dec_return(&oom_victims)) > wake_up_all(&oom_victims_wait); > } > > -- > 2.3.3 > -- Michal Hocko SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@suse.cz> To: Johannes Weiner <hannes@cmpxchg.org> Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@linux-foundation.org>, Andrew Morton <akpm@linux-foundation.org>, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>, Huang Ying <ying.huang@intel.com>, Andrea Arcangeli <aarcange@redhat.com>, Dave Chinner <david@fromorbit.com>, Theodore Ts'o <tytso@mit.edu> Subject: Re: [patch 05/12] mm: oom_kill: generalize OOM progress waitqueue Date: Thu, 26 Mar 2015 14:03:50 +0100 [thread overview] Message-ID: <20150326130350.GH15257@dhcp22.suse.cz> (raw) In-Reply-To: <1427264236-17249-6-git-send-email-hannes@cmpxchg.org> On Wed 25-03-15 02:17:09, Johannes Weiner wrote: > It turns out that the mechanism to wait for exiting OOM victims is > less generic than it looks: it won't issue wakeups unless the OOM > killer is disabled. > > The reason this check was added was the thought that, since only the > OOM disabling code would wait on this queue, wakeup operations could > be saved when that specific consumer is known to be absent. > > However, this is quite the handgrenade. Later attempts to reuse the > waitqueue for other purposes will lead to completely unexpected bugs > and the failure mode will appear seemingly illogical. Generally, > providers shouldn't make unnecessary assumptions about consumers. > > This could have been replaced with waitqueue_active(), but it only > saves a few instructions in one of the coldest paths in the kernel. > Simply remove it. > > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> > --- > mm/oom_kill.c | 6 +----- > 1 file changed, 1 insertion(+), 5 deletions(-) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 88aa9ba40fa5..d3490b019d46 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -437,11 +437,7 @@ void exit_oom_victim(void) > { > clear_thread_flag(TIF_MEMDIE); > > - /* > - * There is no need to signal the lasst oom_victim if there > - * is nobody who cares. > - */ > - if (!atomic_dec_return(&oom_victims) && oom_killer_disabled) > + if (!atomic_dec_return(&oom_victims)) > wake_up_all(&oom_victims_wait); > } > > -- > 2.3.3 > -- Michal Hocko SUSE Labs -- 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: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2015-03-26 13:03 UTC|newest] Thread overview: 138+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-03-25 6:17 [patch 00/12] mm: page_alloc: improve OOM mechanism and policy Johannes Weiner 2015-03-25 6:17 ` Johannes Weiner 2015-03-25 6:17 ` [patch 01/12] mm: oom_kill: remove unnecessary locking in oom_enable() Johannes Weiner 2015-03-25 6:17 ` Johannes Weiner 2015-03-26 0:51 ` David Rientjes 2015-03-26 0:51 ` David Rientjes 2015-03-26 11:51 ` Michal Hocko 2015-03-26 11:51 ` Michal Hocko 2015-03-26 13:18 ` Michal Hocko 2015-03-26 13:18 ` Michal Hocko 2015-03-26 19:30 ` David Rientjes 2015-03-26 19:30 ` David Rientjes 2015-03-26 11:43 ` Michal Hocko 2015-03-26 11:43 ` Michal Hocko 2015-03-26 20:05 ` David Rientjes 2015-03-26 20:05 ` David Rientjes 2015-03-25 6:17 ` [patch 02/12] mm: oom_kill: clean up victim marking and exiting interfaces Johannes Weiner 2015-03-25 6:17 ` Johannes Weiner 2015-03-26 3:34 ` David Rientjes 2015-03-26 3:34 ` David Rientjes 2015-03-26 11:54 ` Michal Hocko 2015-03-26 11:54 ` Michal Hocko 2015-03-25 6:17 ` [patch 03/12] mm: oom_kill: switch test-and-clear of known TIF_MEMDIE to clear Johannes Weiner 2015-03-25 6:17 ` Johannes Weiner 2015-03-26 3:31 ` David Rientjes 2015-03-26 3:31 ` David Rientjes 2015-03-26 11:05 ` Johannes Weiner 2015-03-26 11:05 ` Johannes Weiner 2015-03-26 19:50 ` David Rientjes 2015-03-26 19:50 ` David Rientjes 2015-03-30 14:48 ` Michal Hocko 2015-03-30 14:48 ` Michal Hocko 2015-04-02 23:01 ` [patch] android, lmk: avoid setting TIF_MEMDIE if process has already exited David Rientjes 2015-04-02 23:01 ` David Rientjes 2015-04-28 22:50 ` [patch resend] " David Rientjes 2015-04-28 22:50 ` David Rientjes 2015-03-26 11:57 ` [patch 03/12] mm: oom_kill: switch test-and-clear of known TIF_MEMDIE to clear Michal Hocko 2015-03-26 11:57 ` Michal Hocko 2015-03-25 6:17 ` [patch 04/12] mm: oom_kill: remove unnecessary locking in exit_oom_victim() Johannes Weiner 2015-03-25 6:17 ` Johannes Weiner 2015-03-26 12:53 ` Michal Hocko 2015-03-26 12:53 ` Michal Hocko 2015-03-26 13:01 ` Michal Hocko 2015-03-26 13:01 ` Michal Hocko 2015-03-26 15:10 ` Johannes Weiner 2015-03-26 15:10 ` Johannes Weiner 2015-03-26 15:04 ` Johannes Weiner 2015-03-26 15:04 ` Johannes Weiner 2015-03-25 6:17 ` [patch 05/12] mm: oom_kill: generalize OOM progress waitqueue Johannes Weiner 2015-03-25 6:17 ` Johannes Weiner 2015-03-26 13:03 ` Michal Hocko [this message] 2015-03-26 13:03 ` Michal Hocko 2015-03-25 6:17 ` [patch 06/12] mm: oom_kill: simplify OOM killer locking Johannes Weiner 2015-03-25 6:17 ` Johannes Weiner 2015-03-26 13:31 ` Michal Hocko 2015-03-26 13:31 ` Michal Hocko 2015-03-26 15:17 ` Johannes Weiner 2015-03-26 15:17 ` Johannes Weiner 2015-03-26 16:07 ` Michal Hocko 2015-03-26 16:07 ` Michal Hocko 2015-03-25 6:17 ` [patch 07/12] mm: page_alloc: inline should_alloc_retry() Johannes Weiner 2015-03-25 6:17 ` Johannes Weiner 2015-03-26 14:11 ` Michal Hocko 2015-03-26 14:11 ` Michal Hocko 2015-03-26 15:18 ` Johannes Weiner 2015-03-26 15:18 ` Johannes Weiner 2015-03-25 6:17 ` [patch 08/12] mm: page_alloc: wait for OOM killer progress before retrying Johannes Weiner 2015-03-25 6:17 ` Johannes Weiner 2015-03-25 14:15 ` Tetsuo Handa 2015-03-25 14:15 ` Tetsuo Handa 2015-03-25 17:01 ` Vlastimil Babka 2015-03-25 17:01 ` Vlastimil Babka 2015-03-26 11:28 ` Johannes Weiner 2015-03-26 11:28 ` Johannes Weiner 2015-03-26 11:24 ` Johannes Weiner 2015-03-26 11:24 ` Johannes Weiner 2015-03-26 14:32 ` Michal Hocko 2015-03-26 14:32 ` Michal Hocko 2015-03-26 15:23 ` Johannes Weiner 2015-03-26 15:23 ` Johannes Weiner 2015-03-26 15:38 ` Michal Hocko 2015-03-26 15:38 ` Michal Hocko 2015-03-26 18:17 ` Johannes Weiner 2015-03-26 18:17 ` Johannes Weiner 2015-03-27 14:01 ` [patch 08/12] mm: page_alloc: wait for OOM killer progressbefore retrying Tetsuo Handa 2015-03-27 14:01 ` Tetsuo Handa 2015-03-26 15:58 ` [patch 08/12] mm: page_alloc: wait for OOM killer progress before retrying Michal Hocko 2015-03-26 15:58 ` Michal Hocko 2015-03-26 18:23 ` Johannes Weiner 2015-03-26 18:23 ` Johannes Weiner 2015-03-25 6:17 ` [patch 09/12] mm: page_alloc: private memory reserves for OOM-killing allocations Johannes Weiner 2015-03-25 6:17 ` Johannes Weiner 2015-04-14 16:49 ` Michal Hocko 2015-04-14 16:49 ` Michal Hocko 2015-04-24 19:13 ` Johannes Weiner 2015-04-24 19:13 ` Johannes Weiner 2015-03-25 6:17 ` [patch 10/12] mm: page_alloc: emergency reserve access for __GFP_NOFAIL allocations Johannes Weiner 2015-03-25 6:17 ` Johannes Weiner 2015-04-14 16:55 ` Michal Hocko 2015-04-14 16:55 ` Michal Hocko 2015-03-25 6:17 ` [patch 11/12] mm: page_alloc: do not lock up GFP_NOFS allocations upon OOM Johannes Weiner 2015-03-25 6:17 ` Johannes Weiner 2015-03-26 14:50 ` Michal Hocko 2015-03-26 14:50 ` Michal Hocko 2015-03-25 6:17 ` [patch 12/12] mm: page_alloc: do not lock up low-order " Johannes Weiner 2015-03-25 6:17 ` Johannes Weiner 2015-03-26 15:32 ` Michal Hocko 2015-03-26 15:32 ` Michal Hocko 2015-03-26 19:58 ` [patch 00/12] mm: page_alloc: improve OOM mechanism and policy Dave Chinner 2015-03-26 19:58 ` Dave Chinner 2015-03-27 15:05 ` Johannes Weiner 2015-03-27 15:05 ` Johannes Weiner 2015-03-30 0:32 ` Dave Chinner 2015-03-30 0:32 ` Dave Chinner 2015-03-30 19:31 ` Johannes Weiner 2015-03-30 19:31 ` Johannes Weiner 2015-04-01 15:19 ` Michal Hocko 2015-04-01 15:19 ` Michal Hocko 2015-04-01 21:39 ` Dave Chinner 2015-04-01 21:39 ` Dave Chinner 2015-04-02 7:29 ` Michal Hocko 2015-04-02 7:29 ` Michal Hocko 2015-04-07 14:18 ` Johannes Weiner 2015-04-07 14:18 ` Johannes Weiner 2015-04-11 7:29 ` Tetsuo Handa 2015-04-11 7:29 ` Tetsuo Handa 2015-04-13 12:49 ` Michal Hocko 2015-04-13 12:49 ` Michal Hocko 2015-04-13 12:46 ` Michal Hocko 2015-04-13 12:46 ` Michal Hocko 2015-04-14 0:11 ` Dave Chinner 2015-04-14 0:11 ` Dave Chinner 2015-04-14 7:20 ` Michal Hocko 2015-04-14 7:20 ` Michal Hocko 2015-04-14 10:36 ` Johannes Weiner 2015-04-14 10:36 ` Johannes Weiner 2015-04-14 14:23 ` Michal Hocko 2015-04-14 14:23 ` Michal Hocko
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20150326130350.GH15257@dhcp22.suse.cz \ --to=mhocko@suse.cz \ --cc=aarcange@redhat.com \ --cc=akpm@linux-foundation.org \ --cc=david@fromorbit.com \ --cc=hannes@cmpxchg.org \ --cc=linux-fsdevel@vger.kernel.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-mm@kvack.org \ --cc=penguin-kernel@I-love.SAKURA.ne.jp \ --cc=torvalds@linux-foundation.org \ --cc=tytso@mit.edu \ --cc=ying.huang@intel.com \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.