From: sashiko-bot@kernel.org
To: "SJ Park" <sj@kernel.org>
Cc: damon@lists.linux.dev
Subject: Re: [PATCH 4/9] mm/damon/stat: avoid 32-bit overflow in idle percentiles
Date: Mon, 02 Nov 2026 15:31:32 +0000 [thread overview]
Message-ID: <sashiko-outbox-193670@kernel.org> (raw)
In-Reply-To: <20261102150757.93058-5-sj@kernel.org>
> From: Aveline Noir <jm5905938@gmail.com>
>
> On 32-bit, accounted_bytes * 100 can wrap before division by total_sz.
> Some entries in memory_idle_ms_percentiles then keep their old values
> instead of being updated.
>
> For example, a 256 MiB i386 QEMU guest reported p0=19200 ms, but p50 and
> p100 were both zero. The issue was also shared with another mail [1].
>
> Cast accounted_bytes to u64 before multiplying and use div64_ul() for
> the division. Compute the percentage once per region.
>
> Link: https://lore.kernel.org/r/CANOyQmHad1vamnZT12M5yPrJ69==Pt1U0+MGw6u0MuNtr-DRCw@mail.gmail.com [1]
> Link: https://lore.kernel.org/179207592479.3.11595453180868898703@gmail.com
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Aveline Noir <jm5905938@gmail.com>
> Reviewed-by: SJ Park <sj@kernel.org>
> Signed-off-by: SJ Park <sj@kernel.org>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261102150757.93058-1-sj@kernel.org?part=4
next prev parent reply other threads:[~2026-11-02 15:31 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-02 15:07 [PATCH 0/9] mm/damon: various fixes and cleanup of code, test, and docs SJ Park
2026-11-02 15:07 ` [PATCH 1/9] mm/damon/core: remove unnecessary zero-initialization in damon_new_ctx() SJ Park
2026-11-02 15:10 ` sashiko-bot
2026-11-02 15:07 ` [PATCH 2/9] mm/damon/ops-common: align MMU notifier range when clearing PTE young bit SJ Park
2026-11-02 15:22 ` sashiko-bot
2026-11-02 15:07 ` [PATCH 3/9] mm/damon/ops-common: align MMU notifier range when clearing PMD " SJ Park
2026-11-02 15:29 ` sashiko-bot
2026-11-02 15:07 ` [PATCH 4/9] mm/damon/stat: avoid 32-bit overflow in idle percentiles SJ Park
2026-11-02 15:31 ` sashiko-bot [this message]
2026-11-02 15:07 ` [PATCH 5/9] mm/damon/{p,v}addr: skip folios already on the migration target node SJ Park
2026-11-02 15:33 ` sashiko-bot
2026-11-03 14:09 ` SJ Park
2026-11-02 15:07 ` [PATCH 6/9] selftests/damon/sysfs.py: stop obsolete_target shells hanging the test SJ Park
2026-11-02 15:34 ` sashiko-bot
2026-11-02 15:07 ` [PATCH 7/9] mm/damon/reclaim: fix typo and grammar SJ Park
2026-11-02 15:35 ` sashiko-bot
2026-11-02 15:07 ` [PATCH 8/9] Docs/admin-guide/mm/damon/lru_sort: fix grammar and stlye SJ Park
2026-11-02 15:36 ` sashiko-bot
2026-11-03 2:37 ` Daniel Pereira
2026-11-02 15:07 ` [PATCH 9/9] Docs/admin-guide/mm/damon/reclaim: document how to disable watermarks SJ Park
2026-11-02 15:37 ` sashiko-bot
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=sashiko-outbox-193670@kernel.org \
--to=sashiko-bot@kernel.org \
--cc=damon@lists.linux.dev \
--cc=sashiko-reviews@lists.linux.dev \
--cc=sj@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.