From: Herbert Xu <herbert@gondor.apana.org.au>
To: Breno Leitao <leitao@debian.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Thomas Graf <tgraf@suug.ch>, Tejun Heo <tj@kernel.org>,
Hao Luo <haoluo@google.com>, Josh Don <joshdon@google.com>,
Barret Rhoden <brho@google.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] rhashtable: Fix potential deadlock by moving schedule_work outside lock
Date: Fri, 29 Nov 2024 13:47:42 +0800 [thread overview]
Message-ID: <Z0lVftsFRSSkPkld@gondor.apana.org.au> (raw)
In-Reply-To: <20241128-scx_lockdep-v1-1-2315b813b36b@debian.org>
On Thu, Nov 28, 2024 at 04:16:25AM -0800, Breno Leitao wrote:
> Move the hash table growth check and work scheduling outside the
> rht lock to prevent a possible circular locking dependency.
>
> The original implementation could trigger a lockdep warning due to
> a potential deadlock scenario involving nested locks between
> rhashtable bucket, rq lock, and dsq lock. By relocating the
> growth check and work scheduling after releasing the rth lock, we break
> this potential deadlock chain.
>
> This change expands the flexibility of rhashtable by removing
> restrictive locking that previously limited its use in scheduler
> and workqueue contexts.
Could you please explain the deadlock? Is the workqueue system actually
using rhashtable?
Thanks,
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
next prev parent reply other threads:[~2024-11-29 5:48 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-28 12:16 [PATCH] rhashtable: Fix potential deadlock by moving schedule_work outside lock Breno Leitao
2024-11-29 5:47 ` Herbert Xu [this message]
2024-12-02 20:16 ` Breno Leitao
2024-12-03 20:16 ` Tejun Heo
2024-12-04 1:34 ` Herbert Xu
2024-12-12 12:33 ` Herbert Xu
2024-12-21 9:06 ` Herbert Xu
2025-01-02 10:15 ` Breno Leitao
2025-01-09 3:16 ` Michael Kelley
2025-01-09 10:15 ` Breno Leitao
2025-01-10 9:27 ` Herbert Xu
2025-01-10 9:49 ` Breno Leitao
2025-01-10 10:07 ` Herbert Xu
2025-01-10 14:46 ` Zaslonko Mikhail
2025-01-10 16:59 ` Michael Kelley
2025-01-10 17:24 ` [v2 PATCH] rhashtable: Fix rhashtable_try_insert test Herbert Xu
2025-01-10 18:22 ` Michael Kelley
2025-01-14 3:15 ` [v3 " Herbert Xu
2025-01-14 11:58 ` Michael Kelley
2025-01-15 15:15 ` Breno Leitao
2025-01-16 9:10 ` Herbert Xu
2025-01-16 11:48 ` Alexander Gordeev
2025-01-17 13:20 ` Zaslonko Mikhail
2025-01-13 19:50 ` [PATCH] rhashtable: Fix potential deadlock by moving schedule_work outside lock Guenter Roeck
2025-01-14 3:23 ` Herbert Xu
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