From: sashiko-bot@kernel.org
To: "Artem Dinaburg" <artem@trailofbits.com>
Cc: tytso@mit.edu, linux-ext4@vger.kernel.org
Subject: Re: [PATCH 6.6.y 2/2] jbd2: bound shrinker scans by examined checkpoint buffers
Date: Thu, 08 Oct 2026 19:29:13 +0000 [thread overview]
Message-ID: <sashiko-outbox-164523@kernel.org> (raw)
In-Reply-To: <20261008192048.98833-3-artem@trailofbits.com>
> From: Max Kellermann <max.kellermann@ionos.com>
>
> [ Upstream commit 15cb16496446b94e67f7abcb049b8e2c75cd3d02 ]
>
> The jbd2 shrinker currently accounts only checkpoint buffers that it
> successfully releases against nr_to_scan. Busy buffers therefore do not
> consume the scan budget.
>
> If a checkpoint transaction contains mostly busy buffers, the shrinker
> can scan its entire checkpoint list while holding journal->j_list_lock.
> Large checkpoint lists can result in excessive lock hold times and leave
> other CPUs spinning on j_list_lock, causing soft lockups or RCU stalls.
>
> Pass nr_to_scan into journal_shrink_one_cp_list() and decrement it for
> every buffer examined, including busy buffers. Pass NULL from checkpoint
> [ ... ]
> Reviewed-by: Jan Kara <jack@suse.cz>
> Link: https://patch.msgid.link/20260713102229.1598812-3-max.kellermann@ionos.com
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> Assisted-by: LLM
> Signed-off-by: Artem Dinaburg <artem@trailofbits.com>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261008192048.98833-1-artem@trailofbits.com?part=2
next prev parent reply other threads:[~2026-10-08 19:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-08 19:20 [PATCH 6.6.y 0/2] jbd2: backport CVE-2026-89566, CVE-2026-89567 Artem Dinaburg
2026-10-08 19:20 ` [PATCH 6.6.y 1/2] jbd2: check need_resched() when skipping busy checkpoint buffers Artem Dinaburg
2026-10-08 19:26 ` sashiko-bot
2026-10-08 19:20 ` [PATCH 6.6.y 2/2] jbd2: bound shrinker scans by examined " Artem Dinaburg
2026-10-08 19:29 ` sashiko-bot [this message]
2026-10-09 17:09 ` [PATCH 6.6.y 0/2] jbd2: backport CVE-2026-89566, CVE-2026-89567 Sasha Levin
2026-10-09 18:29 ` Theodore Tso
2026-10-10 22:12 ` Artem Dinaburg
2026-10-10 23:53 ` Theodore Tso
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