From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: zhongjiang@huawei.com
Cc: mhocko@suse.cz, akpm@linux-foundation.org, vbabka@suse.cz,
rientjes@google.com, linux-mm@kvack.org, qiuxishi@huawei.com,
guohanjun@huawei.com, hughd@google.com
Subject: Re: [PATCH] mm: fix oom work when memory is under pressure
Date: Sun, 18 Sep 2016 15:13:18 +0900 [thread overview]
Message-ID: <201609181513.FBI69733.FFFHOMLQOJOSVt@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <201609181500.HIC05206.QJOFMOFHOFtLVS@I-love.SAKURA.ne.jp>
Tetsuo Handa wrote:
> As of 4.8-rc6, the OOM reaper cannot take mmap_sem for read at __oom_reap_task()
> because of TIF_MEMDIE thread waiting at ksm_exit() from __mmput() from mmput()
> from exit_mm() from do_exit(). Thus, __oom_reap_task() returns false and
> oom_reap_task() will emit "oom_reaper: unable to reap pid:%d (%s)\n" message.
> Then, oom_reap_task() clears TIF_MEMDIE from that thread, which in turn
> makes oom_scan_process_thread() not to return OOM_SCAN_ABORT because
> atomic_read(&task->signal->oom_victims) becomes 0 due to exit_oom_victim()
> by the OOM reaper. Then, the OOM killer selects next OOM victim because
> ksmd is waking up the OOM killer via a __GFP_FS allocation request.
Oops. As of 4.8-rc6, __oom_reap_task() returns true because of
find_lock_task_mm() returning NULL. Thus, oom_reap_task() clears TIF_MEMDIE
without emitting "oom_reaper: unable to reap pid:%d (%s)\n" message.
>
> Thus, this bug will be completely solved (at the cost of selecting next
> OOM victim) as of 4.8-rc6.
The conclusion is same.
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next prev parent reply other threads:[~2016-09-18 6:13 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-06 14:47 [PATCH] mm: fix oom work when memory is under pressure zhongjiang
2016-09-09 11:44 ` Michal Hocko
2016-09-12 9:51 ` zhong jiang
2016-09-12 11:13 ` Michal Hocko
2016-09-12 13:42 ` zhong jiang
2016-09-12 17:44 ` Michal Hocko
2016-09-13 13:13 ` zhong jiang
2016-09-13 13:28 ` Michal Hocko
2016-09-13 14:01 ` zhong jiang
2016-09-14 7:13 ` zhong jiang
2016-09-14 8:42 ` Michal Hocko
2016-09-14 8:50 ` zhong jiang
2016-09-14 9:05 ` Michal Hocko
2016-09-14 8:52 ` Michal Hocko
2016-09-14 9:25 ` zhong jiang
2016-09-14 11:29 ` Tetsuo Handa
2016-09-14 13:52 ` zhong jiang
2016-09-18 6:00 ` Tetsuo Handa
2016-09-18 6:13 ` Tetsuo Handa [this message]
2016-09-19 4:44 ` zhong jiang
2016-09-19 7:15 ` zhong jiang
2016-09-16 22:13 ` Hugh Dickins
2016-09-17 15:56 ` Michal Hocko
2016-09-18 4:04 ` zhong jiang
2016-09-18 14:42 ` Michal Hocko
2016-09-19 17:27 ` Hugh Dickins
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