Re: [PATCH v2 1/2] mm/damon/core: charge only the part of a region the filter left

[sashiko-bot@kernel.org]

> From: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
> 
> An address range DAMOS filter that partially overlaps a monitoring
> region splits the region at the filter boundary, so the scheme action is
> applied to only one side of it.  damos_apply_scheme() reads the region
> size once on entry, before damos_core_filter_out() performs that split.
> 
> The quota charge and the statistics update therefore account for the
> region as it was before the trim.  schemes/<S>/stats/sz_tried counts
> memory the filter excluded, which Documentation/mm/damon/design.rst says
> is not counted as tried, and with quotas/bytes set the excluded part is
> charged against the budget, throttling the scheme to a fraction of what
> was configured.
> 
> User impact is that DAMOS could unexpectedly slowly run, due to
> over-charged quota.  DAMOS stat could also be confusing.  No critical
> events such as crashes or leask happen.
> 
> Re-read the region size after the core filters have run.
> 
> Fixes: ab9bda001b68 ("mm/damon/core: introduce address range type damos filter")
> Cc: <stable@vger.kernel.org> # 6.6.x
> Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
> Reviewee-by: SJ Park <sj@kernel.org>
> Signed-off-by: SJ Park <sj@kernel.org>

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

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Sashiko AI review · https://sashiko.dev/#/patchset/20260921152443.80132-1-sj@kernel.org?part=1