From: Dave Chinner <david@fromorbit.com> To: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org>, 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>, "Theodore Ts'o" <tytso@mit.edu> Subject: Re: [patch 00/12] mm: page_alloc: improve OOM mechanism and policy Date: Tue, 14 Apr 2015 10:11:18 +1000 [thread overview] Message-ID: <20150414001118.GS15810@dastard> (raw) In-Reply-To: <20150413124614.GA21790@dhcp22.suse.cz> On Mon, Apr 13, 2015 at 02:46:14PM +0200, Michal Hocko wrote: > [Sorry for a late reply] > > On Tue 07-04-15 10:18:22, Johannes Weiner wrote: > > On Wed, Apr 01, 2015 at 05:19:20PM +0200, Michal Hocko wrote: > > My question here would be: are there any NOFS allocations that *don't* > > want this behavior? Does it even make sense to require this separate > > annotation or should we just make it the default? > > > > The argument here was always that NOFS allocations are very limited in > > their reclaim powers and will trigger OOM prematurely. However, the > > way we limit dirty memory these days forces most cache to be clean at > > all times, and direct reclaim in general hasn't been allowed to issue > > page writeback for quite some time. So these days, NOFS reclaim isn't > > really weaker than regular direct reclaim. > > What about [di]cache and some others fs specific shrinkers (and heavy > metadata loads)? We don't do direct reclaim for fs shrinkers in GFP_NOFS context, either. *HOWEVER* The shrinker reclaim we can not execute is deferred to the next context that can do the reclaim, which is usually kswapd. So the reclaim gets done according to the GFP_NOFS memory pressure that is occurring, it is just done in a different context... > > The only exception is that > > it might block writeback, so we'd go OOM if the only reclaimables left > > were dirty pages against that filesystem. That should be acceptable. > > OOM killer is hardly acceptable by most users I've heard from. OOM > killer is the _last_ resort and if the allocation is restricted then > we shouldn't use the big hammer. The allocator might use __GFP_HIGH to > get access to memory reserves if it can fail or __GFP_NOFAIL if it > cannot. With your patches the NOFAIL case would get an access to memory > reserves as well. So I do not really see a reason to change GFP_NOFS vs. > OOM killer semantic. So, really, what we want is something like: #define __GFP_USE_LOWMEM_RESERVE __GFP_HIGH So that it documents the code that is using it effectively and we can find them easily with cscope/grep? Cheers, Dave. -- Dave Chinner david@fromorbit.com
WARNING: multiple messages have this Message-ID (diff)
From: Dave Chinner <david@fromorbit.com> To: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org>, 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>, Theodore Ts'o <tytso@mit.edu> Subject: Re: [patch 00/12] mm: page_alloc: improve OOM mechanism and policy Date: Tue, 14 Apr 2015 10:11:18 +1000 [thread overview] Message-ID: <20150414001118.GS15810@dastard> (raw) In-Reply-To: <20150413124614.GA21790@dhcp22.suse.cz> On Mon, Apr 13, 2015 at 02:46:14PM +0200, Michal Hocko wrote: > [Sorry for a late reply] > > On Tue 07-04-15 10:18:22, Johannes Weiner wrote: > > On Wed, Apr 01, 2015 at 05:19:20PM +0200, Michal Hocko wrote: > > My question here would be: are there any NOFS allocations that *don't* > > want this behavior? Does it even make sense to require this separate > > annotation or should we just make it the default? > > > > The argument here was always that NOFS allocations are very limited in > > their reclaim powers and will trigger OOM prematurely. However, the > > way we limit dirty memory these days forces most cache to be clean at > > all times, and direct reclaim in general hasn't been allowed to issue > > page writeback for quite some time. So these days, NOFS reclaim isn't > > really weaker than regular direct reclaim. > > What about [di]cache and some others fs specific shrinkers (and heavy > metadata loads)? We don't do direct reclaim for fs shrinkers in GFP_NOFS context, either. *HOWEVER* The shrinker reclaim we can not execute is deferred to the next context that can do the reclaim, which is usually kswapd. So the reclaim gets done according to the GFP_NOFS memory pressure that is occurring, it is just done in a different context... > > The only exception is that > > it might block writeback, so we'd go OOM if the only reclaimables left > > were dirty pages against that filesystem. That should be acceptable. > > OOM killer is hardly acceptable by most users I've heard from. OOM > killer is the _last_ resort and if the allocation is restricted then > we shouldn't use the big hammer. The allocator might use __GFP_HIGH to > get access to memory reserves if it can fail or __GFP_NOFAIL if it > cannot. With your patches the NOFAIL case would get an access to memory > reserves as well. So I do not really see a reason to change GFP_NOFS vs. > OOM killer semantic. So, really, what we want is something like: #define __GFP_USE_LOWMEM_RESERVE __GFP_HIGH So that it documents the code that is using it effectively and we can find them easily with cscope/grep? Cheers, Dave. -- Dave Chinner david@fromorbit.com -- 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:[~2015-04-14 0:21 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 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 [this message] 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
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