Re: [PATCH 6.18.y] mm/damon/sysfs: read ops_id only once in damon_sysfs_apply_inputs()

[sashiko-bot@kernel.org]

> damon_sysfs_apply_inputs() reads ops_id twice.  It could race with
> ops_id_store().  As a result, the min_region_sz could wrongly be set up.
> Read it once.
> 
> The user impact is trivial.  Sane users ain't update the parameter in
> parallel.  Even if it happens, the DAMON core layer handles the wrong
> min_region_sz (!is_power_of_2()).  Even if somehow the race ended up
> making a min_region_sz that is different from the user's intention but
> still valid, only monitoring itself runs differently than expected.  No
> critical consequences like kernel panic or memory corruption happen
> 
> The issue was discovered [1] by Sashiko.
> 
> Link: https://lore.kernel.org/20260715031002.108504-7-sj@kernel.org
> Link: https://lore.kernel.org/20260703172417.95426-1-sj@kernel.org [1]
> Fixes: 8d009da32f13 ("mm/damon/sysfs: set damon_ctx->min_sz_region only for paddr use case")
> Signed-off-by: SJ Park <sj@kernel.org>
> Cc: <stable@vger.kernel.org> # 6.18.x
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> (cherry picked from commit 5adaaa28be8a79ddd7e103b171f9d6e14e7fc26e)
> Signed-off-by: SJ Park <sj@kernel.org>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260909032830.119383-1-sj@kernel.org?part=1