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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Qian Cai <cai@lca.pw>
Cc: peterz@infradead.org, mingo@redhat.com,
	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: Tue, 17 Sep 2019 09:16:35 +0200
Message-ID: <20190917071634.c7i3i6jg676ejiw5@linutronix.de> (raw)
In-Reply-To: <1568669494.5576.157.camel@lca.pw>

On 2019-09-16 17:31:34 [-0400], Qian Cai wrote:
…
> get_random_u64() is also busted.
> [  753.486588]  Possible unsafe locking scenario:
> 
> [  753.493890]        CPU0                    CPU1
> [  753.499108]        ----                    ----
> [  753.504324]   lock(batched_entropy_u64.lock);
> [  753.509372]                                lock(&(&zone->lock)->rlock);
> [  753.516675]                                lock(batched_entropy_u64.lock);
> [  753.524238]   lock(random_write_wait.lock);
> [  753.529113] 
>                 *** DEADLOCK ***

This is the same scenario as the previous one in regard to the
batched_entropy_….lock.

Sebastian


  reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-13 16:27 Qian Cai
2019-09-16  9:03 ` Sebastian Andrzej Siewior
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 [this message]
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

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