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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Qian Cai <cai@lca.pw>, peterz@infradead.org, mingo@redhat.com
Cc: akpm@linux-foundation.org, tglx@linutronix.de,
	thgarnie@google.com, tytso@mit.edu, cl@linux.com,
	penberg@kernel.org, rientjes@google.com, will@kernel.org,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	keescook@chromium.org
Subject: Re: [PATCH] mm/slub: fix a deadlock in shuffle_freelist()
Date: Mon, 16 Sep 2019 11:03:36 +0200	[thread overview]
Message-ID: <20190916090336.2mugbds4rrwxh6uz@linutronix.de> (raw)
In-Reply-To: <1568392064-3052-1-git-send-email-cai@lca.pw>

On 2019-09-13 12:27:44 [-0400], Qian Cai wrote:
…
> Chain exists of:
>   random_write_wait.lock --> &rq->lock --> batched_entropy_u32.lock
> 
>  Possible unsafe locking scenario:
> 
>        CPU0                    CPU1
>        ----                    ----
>   lock(batched_entropy_u32.lock);
>                                lock(&rq->lock);
>                                lock(batched_entropy_u32.lock);
>   lock(random_write_wait.lock);

would this deadlock still occur if lockdep knew that
batched_entropy_u32.lock on CPU0 could be acquired at the same time
as CPU1 acquired its batched_entropy_u32.lock?

Sebastian

  reply	other threads:[~2019-09-16  9:03 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-13 16:27 [PATCH] mm/slub: fix a deadlock in shuffle_freelist() Qian Cai
2019-09-16  9:03 ` Sebastian Andrzej Siewior [this message]
2019-09-16 14:01   ` Qian Cai
2019-09-16 19:51     ` Sebastian Andrzej Siewior
2019-09-16 21:31       ` Qian Cai
2019-09-17  7:16         ` Sebastian Andrzej Siewior
2019-09-18 19:59           ` Qian Cai
2019-09-25  9:31 ` Peter Zijlstra
2019-09-25 15:18   ` Qian Cai
2019-09-25 16:45     ` Peter Zijlstra
2019-09-26 12:29       ` Qian Cai
2019-10-01  9:18         ` [PATCH] sched: Avoid spurious lock dependencies Peter Zijlstra
2019-10-01 10:01           ` Valentin Schneider
2019-10-01 11:22           ` Qian Cai
2019-10-01 11:36           ` Srikar Dronamraju
2019-10-01 13:44             ` Peter Zijlstra
2019-10-29 11:10           ` Qian Cai
2019-10-29 12:44             ` Peter Zijlstra
2019-11-12  0:54               ` Qian Cai
2019-11-13 10:06           ` [tip: sched/urgent] sched/core: " tip-bot2 for Peter Zijlstra
2019-11-22 20:01             ` Sebastian Andrzej Siewior
2019-11-22 20:20               ` Peter Zijlstra
2019-11-22 21:03                 ` Qian Cai

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