Re: [RFC PATCH v2] mm/damon/core: reset invalid quota->charge_target_from

[sashiko-bot@kernel.org]

> DAMOS can suddenly stop working if a target process that the quota is
> just fully charged on is terminated.  Fix by catching and processing the
> corner case.
> 
> When DAMOS quota is fully charged, the target and the region to continue
> applying the action in the next round is saved in
> damos_quota->charge_{target,addr}_from.  In the next round, DAMOS
> iterates targets and regions from the beginning.  It skips applying the
> action to the regions until it visits and skips the saved target/region.
> 
> Virtual address space targets become invalid if the process is
> terminated.  Trying to apply the scheme to invalid target is just a
> waste of time.  Hence commit 6e4930e33329 ("mm/damon/core: fix wasteful
> CPU calls by skipping non-existent targets") made the logic to skip
> invalid targets.  However, it does skip before the charged target/region
> [ ... ]
> [1] https://lore.kernel.org/20260830064708.40CA61F000E9@smtp.kernel.org
> 
> Fixes: 6e4930e33329 ("mm/damon/core: fix wasteful CPU calls by skipping non-existent targets")
> Cc: <stable@vger.kernel.org> # 7.0.x
> 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/20260908144246.104162-1-sj@kernel.org?part=1