From: Tejun Heo <tj@kernel.org> To: Andrew Morton <akpm@linux-foundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org>, Michal Hocko <mhocko@kernel.org>, Petr Mladek <pmladek@suse.com>, cgroups@vger.kernel.org, Cyril Hrubis <chrubis@suse.cz>, linux-kernel@vger.kernel.org Subject: [PATCH for-4.6-fixes] memcg: remove lru_add_drain_all() invocation from mem_cgroup_move_charge() Date: Thu, 21 Apr 2016 11:56:52 -0400 [thread overview] Message-ID: <20160421155652.GM7822@mtj.duckdns.org> (raw) In-Reply-To: <20160415191719.GK12583@htj.duckdns.org> mem_cgroup_move_charge() invokes lru_add_drain_all() so that the pvec pages can be moved too. lru_add_drain_all() schedules and flushes work items on system_wq which depends on being able to create new kworkers to make forward progress. Since 1ed1328792ff ("sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem"), a new task can't be created while in the cgroup migration path and the described lru_add_drain_all() invocation can easily lead to a deadlock. Charge moving is best-effort and whether the pvec pages are migrated or not doesn't really matter. Don't call it during charge moving. Eventually, we want to move the actual charge moving outside the migration path. Signed-off-by: Tejun Heo <tj@kernel.org> Debugged-and-tested-by: Petr Mladek <pmladek@suse.com> Reported-by: Cyril Hrubis <chrubis@suse.cz> Reported-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: Michal Hocko <mhocko@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Fixes: 1ed1328792ff ("sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem") Cc: stable@vger.kernel.org # v4.4+ --- Hello, Andrew. This fixes an easily triggered deadlock when using memcg charge moving. While the issue requires more invasive changes, which are being worked on, to plug completely, this works around the immediate issue. Can you please route this through -mm? Thanks. mm/memcontrol.c | 1 - 1 file changed, 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 36db05f..56060c7 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4859,7 +4859,6 @@ static void mem_cgroup_move_charge(struct mm_struct *mm) .mm = mm, }; - lru_add_drain_all(); /* * Signal lock_page_memcg() to take the memcg's move_lock * while we're moving its pages to another memcg. Then wait
WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> To: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org> Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Petr Mladek <pmladek-IBi9RG/b67k@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Cyril Hrubis <chrubis-AlSwsSmVLrQ@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Subject: [PATCH for-4.6-fixes] memcg: remove lru_add_drain_all() invocation from mem_cgroup_move_charge() Date: Thu, 21 Apr 2016 11:56:52 -0400 [thread overview] Message-ID: <20160421155652.GM7822@mtj.duckdns.org> (raw) In-Reply-To: <20160415191719.GK12583-piEFEHQLUPpN0TnZuCh8vA@public.gmane.org> mem_cgroup_move_charge() invokes lru_add_drain_all() so that the pvec pages can be moved too. lru_add_drain_all() schedules and flushes work items on system_wq which depends on being able to create new kworkers to make forward progress. Since 1ed1328792ff ("sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem"), a new task can't be created while in the cgroup migration path and the described lru_add_drain_all() invocation can easily lead to a deadlock. Charge moving is best-effort and whether the pvec pages are migrated or not doesn't really matter. Don't call it during charge moving. Eventually, we want to move the actual charge moving outside the migration path. Signed-off-by: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Debugged-and-tested-by: Petr Mladek <pmladek-IBi9RG/b67k@public.gmane.org> Reported-by: Cyril Hrubis <chrubis-AlSwsSmVLrQ@public.gmane.org> Reported-by: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org> Suggested-by: Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Acked-by: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org> Fixes: 1ed1328792ff ("sched, cgroup: replace signal_struct->group_rwsem with a global percpu_rwsem") Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org # v4.4+ --- Hello, Andrew. This fixes an easily triggered deadlock when using memcg charge moving. While the issue requires more invasive changes, which are being worked on, to plug completely, this works around the immediate issue. Can you please route this through -mm? Thanks. mm/memcontrol.c | 1 - 1 file changed, 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 36db05f..56060c7 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4859,7 +4859,6 @@ static void mem_cgroup_move_charge(struct mm_struct *mm) .mm = mm, }; - lru_add_drain_all(); /* * Signal lock_page_memcg() to take the memcg's move_lock * while we're moving its pages to another memcg. Then wait
next prev parent reply other threads:[~2016-04-21 15:56 UTC|newest] Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-04-13 9:42 [BUG] cgroup/workques/fork: deadlock when moving cgroups Petr Mladek 2016-04-13 18:33 ` Tejun Heo 2016-04-13 18:33 ` Tejun Heo 2016-04-13 18:57 ` Tejun Heo 2016-04-13 18:57 ` Tejun Heo 2016-04-13 19:23 ` Michal Hocko 2016-04-13 19:23 ` Michal Hocko 2016-04-13 19:28 ` Michal Hocko 2016-04-13 19:28 ` Michal Hocko 2016-04-13 19:37 ` Tejun Heo 2016-04-13 19:48 ` Michal Hocko 2016-04-14 7:06 ` Michal Hocko 2016-04-14 7:06 ` Michal Hocko 2016-04-14 15:32 ` Tejun Heo 2016-04-14 15:32 ` Tejun Heo 2016-04-14 17:50 ` Johannes Weiner 2016-04-15 7:06 ` Michal Hocko 2016-04-15 14:38 ` Tejun Heo 2016-04-15 14:38 ` Tejun Heo 2016-04-15 15:08 ` Michal Hocko 2016-04-15 15:08 ` Michal Hocko 2016-04-15 15:25 ` Tejun Heo 2016-04-15 15:25 ` Tejun Heo 2016-04-17 12:00 ` Michal Hocko 2016-04-17 12:00 ` Michal Hocko 2016-04-18 14:40 ` Petr Mladek 2016-04-18 14:40 ` Petr Mladek 2016-04-19 14:01 ` Michal Hocko 2016-04-19 14:01 ` Michal Hocko 2016-04-19 15:39 ` Petr Mladek 2016-04-15 19:17 ` [PATCH for-4.6-fixes] memcg: remove lru_add_drain_all() invocation from mem_cgroup_move_charge() Tejun Heo 2016-04-17 12:07 ` Michal Hocko 2016-04-17 12:07 ` Michal Hocko 2016-04-20 21:29 ` Tejun Heo 2016-04-20 21:29 ` Tejun Heo 2016-04-21 3:27 ` Michal Hocko 2016-04-21 3:27 ` Michal Hocko 2016-04-21 15:00 ` Petr Mladek 2016-04-21 15:00 ` Petr Mladek 2016-04-21 15:51 ` Tejun Heo 2016-04-21 23:06 ` [PATCH 1/2] cgroup, cpuset: replace cpuset_post_attach_flush() with cgroup_subsys->post_attach callback Tejun Heo 2016-04-21 23:06 ` Tejun Heo 2016-04-21 23:09 ` [PATCH 2/2] memcg: relocate charge moving from ->attach to ->post_attach Tejun Heo 2016-04-21 23:09 ` Tejun Heo 2016-04-22 13:57 ` Petr Mladek 2016-04-22 13:57 ` Petr Mladek 2016-04-25 8:25 ` Michal Hocko 2016-04-25 8:25 ` Michal Hocko 2016-04-25 19:42 ` Tejun Heo 2016-04-25 19:42 ` Tejun Heo 2016-04-25 19:44 ` Tejun Heo 2016-04-25 19:44 ` Tejun Heo 2016-04-21 23:11 ` [PATCH 1/2] cgroup, cpuset: replace cpuset_post_attach_flush() with cgroup_subsys->post_attach callback Tejun Heo 2016-04-21 23:11 ` Tejun Heo 2016-04-21 15:56 ` Tejun Heo [this message] 2016-04-21 15:56 ` [PATCH for-4.6-fixes] memcg: remove lru_add_drain_all() invocation from mem_cgroup_move_charge() Tejun Heo
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