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From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: Qian Cai <cai@lca.pw>, Mel Gorman <mgorman@techsingularity.net>,
	Vlastimil Babka <vbabka@suse.cz>
Cc: syzbot <syzbot+93d94a001cfbce9e60e1@syzkaller.appspotmail.com>,
	aarcange@redhat.com, akpm@linux-foundation.org,
	kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, linux@dominikbrodowski.net, mhocko@suse.com,
	rientjes@google.com, syzkaller-bugs@googlegroups.com,
	xieyisheng1@huawei.com, zhongjiang@huawei.com,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>
Subject: Re: possible deadlock in __wake_up_common_lock
Date: Thu, 3 Jan 2019 10:28:45 +0900	[thread overview]
Message-ID: <530f88a1-3aa1-c36f-f487-7e5e33402fb0@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <73c41960-e282-e2ec-4edd-788a1f49f06a@lca.pw>

On 2019/01/03 3:19, Qian Cai wrote:
> On 1/2/19 1:06 PM, Mel Gorman wrote:
> 
>> While I recognise there is no test case available, how often does this
>> trigger in syzbot as it would be nice to have some confirmation any
>> patch is really fixing the problem.
> 
> I think I did manage to trigger this every time running a mmap() workload
> causing swapping and a low-memory situation [1].
> 
> [1]
> https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/mem/oom/oom01.c

wakeup_kswapd() is called because tlb_next_batch() is doing GFP_NOWAIT
allocation. But since tlb_next_batch() can tolerate allocation failure,
does below change in tlb_next_batch() help?

#define GFP_NOWAIT      (__GFP_KSWAPD_RECLAIM)

-	batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
+	batch = (void *)__get_free_pages(__GFP_NOWARN, 0);

  reply	other threads:[~2019-01-03  1:29 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-02  8:51 syzbot
2019-01-02  8:51 ` syzbot
2019-01-02 12:51 ` Vlastimil Babka
2019-01-02 18:06   ` Mel Gorman
2019-01-02 18:19     ` Qian Cai
2019-01-03  1:28       ` Tetsuo Handa [this message]
2019-01-03  3:27         ` Qian Cai
2019-01-02 18:29     ` Dmitry Vyukov
2019-01-02 18:29       ` Dmitry Vyukov
2019-01-03 16:37       ` Mel Gorman
2019-01-03 19:40         ` Qian Cai
2019-01-03 22:54           ` Mel Gorman
2019-01-07  9:52   ` Peter Zijlstra
2019-01-07 20:46     ` Johannes Weiner
2019-01-07 21:29       ` Peter Zijlstra
2019-01-07 21:33         ` Peter Zijlstra
2019-01-08 13:08   ` Peter Zijlstra

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