From: Michal Hocko <mhocko@kernel.org> To: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org>, Shakeel Butt <shakeelb@google.com>, Alexander Viro <viro@zeniv.linux.org.uk>, Vladimir Davydov <vdavydov.dev@gmail.com>, Andrew Morton <akpm@linux-foundation.org>, Linux MM <linux-mm@kvack.org>, linux-fsdevel@vger.kernel.org, LKML <linux-kernel@vger.kernel.org> Subject: Re: [PATCH] fs, mm: account filp and names caches to kmemcg Date: Fri, 13 Oct 2017 08:51:50 +0200 [thread overview] Message-ID: <20171013065150.dzesflih5ot2z3px@dhcp22.suse.cz> (raw) In-Reply-To: <xr937evzyl5p.fsf@gthelen.svl.corp.google.com> On Thu 12-10-17 16:57:22, Greg Thelen wrote: [...] > Overcharging kmem with deferred reconciliation sounds good to me. > > A few comments (not reasons to avoid this): > > 1) If a task is moved between memcg it seems possible to overcharge > multiple oom memcg for different kmem/user allocations. > mem_cgroup_oom_synchronize() would see at most one oom memcg in > current->memcg_in_oom. Thus it'd only reconcile a single memcg. But > that seems pretty rare and the next charge to any of the other memcg > would reconcile them. This is a general problem for the cgroup v2 memcg oom handling. > 2) if a kernel thread charges kmem on behalf of a client mm then there > is no good place to call mem_cgroup_oom_synchronize(), short of > launching a work item in mem_cgroup_oom(). I don't we have anything > like that yet. So nothing to worry about. If we do invoke the OOM killer from the charge path, it shouldn't be a problem. > 3) it's debatable if mem_cgroup_oom_synchronize() should first attempt > reclaim before killing. But that's a whole 'nother thread. Again, this shouldn't be an issue if we invoke the oom killer from the charge path. > 4) overcharging with deferred reconciliation could also be used for user > pages. But I haven't looked at the code long enough to know if this > would be a net win. It would solve g-u-p issues failing with ENOMEM unexpectedly just because of memcg charge failure. -- Michal Hocko SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org> To: Greg Thelen <gthelen@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org>, Shakeel Butt <shakeelb@google.com>, Alexander Viro <viro@zeniv.linux.org.uk>, Vladimir Davydov <vdavydov.dev@gmail.com>, Andrew Morton <akpm@linux-foundation.org>, Linux MM <linux-mm@kvack.org>, linux-fsdevel@vger.kernel.org, LKML <linux-kernel@vger.kernel.org> Subject: Re: [PATCH] fs, mm: account filp and names caches to kmemcg Date: Fri, 13 Oct 2017 08:51:50 +0200 [thread overview] Message-ID: <20171013065150.dzesflih5ot2z3px@dhcp22.suse.cz> (raw) In-Reply-To: <xr937evzyl5p.fsf@gthelen.svl.corp.google.com> On Thu 12-10-17 16:57:22, Greg Thelen wrote: [...] > Overcharging kmem with deferred reconciliation sounds good to me. > > A few comments (not reasons to avoid this): > > 1) If a task is moved between memcg it seems possible to overcharge > multiple oom memcg for different kmem/user allocations. > mem_cgroup_oom_synchronize() would see at most one oom memcg in > current->memcg_in_oom. Thus it'd only reconcile a single memcg. But > that seems pretty rare and the next charge to any of the other memcg > would reconcile them. This is a general problem for the cgroup v2 memcg oom handling. > 2) if a kernel thread charges kmem on behalf of a client mm then there > is no good place to call mem_cgroup_oom_synchronize(), short of > launching a work item in mem_cgroup_oom(). I don't we have anything > like that yet. So nothing to worry about. If we do invoke the OOM killer from the charge path, it shouldn't be a problem. > 3) it's debatable if mem_cgroup_oom_synchronize() should first attempt > reclaim before killing. But that's a whole 'nother thread. Again, this shouldn't be an issue if we invoke the oom killer from the charge path. > 4) overcharging with deferred reconciliation could also be used for user > pages. But I haven't looked at the code long enough to know if this > would be a net win. It would solve g-u-p issues failing with ENOMEM unexpectedly just because of memcg charge failure. -- 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:[~2017-10-13 6:51 UTC|newest] Thread overview: 104+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-10-05 22:21 [PATCH] fs, mm: account filp and names caches to kmemcg Shakeel Butt 2017-10-05 22:21 ` Shakeel Butt 2017-10-06 7:59 ` Michal Hocko 2017-10-06 7:59 ` Michal Hocko 2017-10-06 19:33 ` Shakeel Butt 2017-10-06 19:33 ` Shakeel Butt 2017-10-09 6:24 ` Michal Hocko 2017-10-09 6:24 ` Michal Hocko 2017-10-09 17:52 ` Greg Thelen 2017-10-09 17:52 ` Greg Thelen 2017-10-09 18:04 ` Michal Hocko 2017-10-09 18:04 ` Michal Hocko 2017-10-09 18:17 ` Michal Hocko 2017-10-09 18:17 ` Michal Hocko 2017-10-10 9:10 ` Michal Hocko 2017-10-10 9:10 ` Michal Hocko 2017-10-10 22:21 ` Shakeel Butt 2017-10-10 22:21 ` Shakeel Butt 2017-10-11 9:09 ` Michal Hocko 2017-10-11 9:09 ` Michal Hocko 2017-10-09 20:26 ` Johannes Weiner 2017-10-09 20:26 ` Johannes Weiner 2017-10-10 9:14 ` Michal Hocko 2017-10-10 9:14 ` Michal Hocko 2017-10-10 14:17 ` Johannes Weiner 2017-10-10 14:17 ` Johannes Weiner 2017-10-10 14:24 ` Michal Hocko 2017-10-10 14:24 ` Michal Hocko 2017-10-12 19:03 ` Johannes Weiner 2017-10-12 19:03 ` Johannes Weiner 2017-10-12 23:57 ` Greg Thelen 2017-10-12 23:57 ` Greg Thelen 2017-10-13 6:51 ` Michal Hocko [this message] 2017-10-13 6:51 ` Michal Hocko 2017-10-13 6:35 ` Michal Hocko 2017-10-13 6:35 ` Michal Hocko 2017-10-13 7:00 ` Michal Hocko 2017-10-13 7:00 ` Michal Hocko 2017-10-13 15:24 ` Michal Hocko 2017-10-13 15:24 ` Michal Hocko 2017-10-24 12:18 ` Michal Hocko 2017-10-24 12:18 ` Michal Hocko 2017-10-24 17:54 ` Johannes Weiner 2017-10-24 17:54 ` Johannes Weiner 2017-10-24 16:06 ` Johannes Weiner 2017-10-24 16:06 ` Johannes Weiner 2017-10-24 16:22 ` Michal Hocko 2017-10-24 16:22 ` Michal Hocko 2017-10-24 17:23 ` Johannes Weiner 2017-10-24 17:23 ` Johannes Weiner 2017-10-24 17:55 ` Michal Hocko 2017-10-24 17:55 ` Michal Hocko 2017-10-24 18:58 ` Johannes Weiner 2017-10-24 18:58 ` Johannes Weiner 2017-10-24 20:15 ` Michal Hocko 2017-10-24 20:15 ` Michal Hocko 2017-10-25 6:51 ` Greg Thelen 2017-10-25 6:51 ` Greg Thelen 2017-10-25 7:15 ` Michal Hocko 2017-10-25 7:15 ` Michal Hocko 2017-10-25 13:11 ` Johannes Weiner 2017-10-25 13:11 ` Johannes Weiner 2017-10-25 14:12 ` Michal Hocko 2017-10-25 14:12 ` Michal Hocko 2017-10-25 16:44 ` Johannes Weiner 2017-10-25 16:44 ` Johannes Weiner 2017-10-25 17:29 ` Michal Hocko 2017-10-25 17:29 ` Michal Hocko 2017-10-25 18:11 ` Johannes Weiner 2017-10-25 18:11 ` Johannes Weiner 2017-10-25 19:00 ` Michal Hocko 2017-10-25 19:00 ` Michal Hocko 2017-10-25 21:13 ` Johannes Weiner 2017-10-25 21:13 ` Johannes Weiner 2017-10-25 22:49 ` Greg Thelen 2017-10-25 22:49 ` Greg Thelen 2017-10-26 7:49 ` Michal Hocko 2017-10-26 7:49 ` Michal Hocko 2017-10-26 12:45 ` Tetsuo Handa 2017-10-26 12:45 ` Tetsuo Handa 2017-10-26 14:31 ` Johannes Weiner 2017-10-26 14:31 ` Johannes Weiner 2017-10-26 19:56 ` Greg Thelen 2017-10-26 19:56 ` Greg Thelen 2017-10-27 8:20 ` Michal Hocko 2017-10-27 8:20 ` Michal Hocko 2017-10-27 20:50 ` Shakeel Butt 2017-10-27 20:50 ` Shakeel Butt 2017-10-30 8:29 ` Michal Hocko 2017-10-30 8:29 ` Michal Hocko 2017-10-30 19:28 ` Shakeel Butt 2017-10-30 19:28 ` Shakeel Butt 2017-10-31 8:00 ` Michal Hocko 2017-10-31 8:00 ` Michal Hocko 2017-10-31 16:49 ` Johannes Weiner 2017-10-31 16:49 ` Johannes Weiner 2017-10-31 18:50 ` Michal Hocko 2017-10-31 18:50 ` Michal Hocko 2017-10-24 15:45 ` Johannes Weiner 2017-10-24 15:45 ` Johannes Weiner 2017-10-24 16:30 ` Michal Hocko 2017-10-24 16:30 ` Michal Hocko 2017-10-10 23:32 ` Al Viro 2017-10-10 23:32 ` Al Viro
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