From: Michal Hocko <mhocko@kernel.org>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
linux-mm@lists.ewheeler.net, Minchan Kim <minchan@kernel.org>,
Huang Ying <ying.huang@intel.com>,
Mel Gorman <mgorman@techsingularity.net>,
Vladimir Davydov <vdavydov.dev@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Shakeel Butt <shakeelb@google.com>,
Greg Thelen <gthelen@google.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] mm,vmscan: Kill global shrinker lock.
Date: Thu, 25 Jan 2018 09:36:04 +0100 [thread overview]
Message-ID: <20180125083604.GM28465@dhcp22.suse.cz> (raw)
In-Reply-To: <201801250204.w0P24NKZ033992@www262.sakura.ne.jp>
On Thu 25-01-18 11:04:23, Tetsuo Handa wrote:
> Michal Hocko wrote:
> > On Wed 15-11-17 09:00:20, Johannes Weiner wrote:
> > > In any case, Minchan's lock breaking seems way preferable over that
> > > level of headscratching complexity for an unusual case like Shakeel's.
> >
> > agreed! I would go the more complex way only if it turns out that early
> > break out causes some real problems.
> >
>
> Eric Wheeler wrote (at http://lkml.kernel.org/r/alpine.LRH.2.11.1801242349220.30642@mail.ewheeler.net ):
> > Hello all,
> >
> > We are getting processes stuck with /proc/pid/stack listing the following:
>
> Yes, I think that this is a silent OOM lockup.
>
> >
> > [<ffffffffac0cd0d2>] io_schedule+0x12/0x40
> > [<ffffffffac1b4695>] __lock_page+0x105/0x150
> > [<ffffffffac1b4dc1>] pagecache_get_page+0x161/0x210
> > [<ffffffffac1d4ab4>] shmem_unused_huge_shrink+0x334/0x3f0
> > [<ffffffffac251546>] super_cache_scan+0x176/0x180
> > [<ffffffffac1cb6c5>] shrink_slab+0x275/0x460
> > [<ffffffffac1d0b8e>] shrink_node+0x10e/0x320
> > [<ffffffffac1d0f3d>] node_reclaim+0x19d/0x250
> > [<ffffffffac1be0aa>] get_page_from_freelist+0x16a/0xac0
> > [<ffffffffac1bed87>] __alloc_pages_nodemask+0x107/0x290
> > [<ffffffffac06dbc3>] pte_alloc_one+0x13/0x40
> > [<ffffffffac1ef329>] __pte_alloc+0x19/0x100
> > [<ffffffffac1f17b8>] alloc_set_pte+0x468/0x4c0
> > [<ffffffffac1f184a>] finish_fault+0x3a/0x70
> > [<ffffffffac1f369a>] __handle_mm_fault+0x94a/0x1190
> > [<ffffffffac1f3fa4>] handle_mm_fault+0xc4/0x1d0
> > [<ffffffffac0682a3>] __do_page_fault+0x253/0x4d0
> > [<ffffffffac068553>] do_page_fault+0x33/0x120
> > [<ffffffffac8019dc>] page_fault+0x4c/0x60
> >
> >
> > For some reason io_schedule is not coming back, so shrinker_rwsem never
> > gets an up_read. When this happens, other processes like libvirt get stuck
> > trying to start VMs with the /proc/pid/stack of libvirtd looking like so,
> > while register_shrinker waits for shrinker_rwsem to be released:
> >
> > [<ffffffffac7538d3>] call_rwsem_down_write_failed+0x13/0x20
> > [<ffffffffac1cb985>] register_shrinker+0x45/0xa0
> > [<ffffffffac250f68>] sget_userns+0x468/0x4a0
> > [<ffffffffac25106a>] mount_nodev+0x2a/0xa0
> > [<ffffffffac251be4>] mount_fs+0x34/0x150
> > [<ffffffffac2701f2>] vfs_kern_mount+0x62/0x120
> > [<ffffffffac272a0e>] do_mount+0x1ee/0xc50
> > [<ffffffffac27377e>] SyS_mount+0x7e/0xd0
> > [<ffffffffac003831>] do_syscall_64+0x61/0x1a0
> > [<ffffffffac80012c>] entry_SYSCALL64_slow_path+0x25/0x25
> > [<ffffffffffffffff>] 0xffffffffffffffff
> >
>
> If io_schedule() depends on somebody else's memory allocation request, that
> somebody else will call shrink_slab() and down_read_trylock(&shrinker_rwsem)
> will fail without making progress. This means that that somebody else will
> forever retry as long as should_continue_reclaim() returns true.
I would rather understand the problem than speculate here. I strongly
suspect somebody simply didn't unlock the page.
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2018-01-25 8:36 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-13 21:37 [PATCH 1/2] mm,vmscan: Kill global shrinker lock Tetsuo Handa
2017-11-13 21:37 ` [PATCH 2/2] mm,vmscan: Allow parallel registration/unregistration of shrinkers Tetsuo Handa
2017-11-13 22:05 ` [PATCH 1/2] mm,vmscan: Kill global shrinker lock Shakeel Butt
2017-11-15 0:56 ` Minchan Kim
2017-11-15 6:28 ` Shakeel Butt
2017-11-16 0:46 ` Minchan Kim
2017-11-16 1:41 ` Shakeel Butt
2017-11-16 4:50 ` Minchan Kim
2017-11-15 8:56 ` Michal Hocko
2017-11-15 9:18 ` Michal Hocko
2017-11-16 17:44 ` Johannes Weiner
2017-11-23 23:46 ` Minchan Kim
2017-11-15 9:02 ` Michal Hocko
2017-11-15 10:58 ` Tetsuo Handa
2017-11-15 11:51 ` Michal Hocko
2017-11-16 0:56 ` Minchan Kim
2017-11-15 13:28 ` Johannes Weiner
2017-11-16 10:56 ` Tetsuo Handa
2017-11-15 14:00 ` Johannes Weiner
2017-11-15 14:11 ` Michal Hocko
2018-01-25 2:04 ` Tetsuo Handa
2018-01-25 8:36 ` Michal Hocko [this message]
2018-01-25 10:56 ` Tetsuo Handa
2018-01-25 11:41 ` Michal Hocko
2018-01-25 22:19 ` Eric Wheeler
2018-01-26 3:12 ` Tetsuo Handa
2018-01-26 10:08 ` Michal Hocko
2017-11-17 17:35 ` Christoph Hellwig
2017-11-17 17:41 ` Shakeel Butt
2017-11-17 17:53 ` Shakeel Butt
2017-11-17 18:36 ` Christoph Hellwig
2017-11-20 9:25 ` Michal Hocko
2017-11-20 9:33 ` Christoph Hellwig
2017-11-20 9:42 ` Michal Hocko
2017-11-20 10:41 ` Christoph Hellwig
2017-11-20 10:56 ` Tetsuo Handa
2017-11-20 18:28 ` Paul E. McKenney
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