Re: [RFC PATCH 4/6] mm/damon/sysfs-schemes: drop redundant and racy zero target_value check

[sashiko-bot@kernel.org]

> DAMON sysfs interface disallowed zero target_value because it could
> result in divide-by-zero in damos_quota_store().  Because similar checks
> were duplicated to other DAMON API callers, a patch series that starts
> with commit 610c4438fb66 ("mm/damon/core: error
> damos_commit_quota_goal() for zero target_value") added a same check in
> the core layer central parameters, and dropped redundant checks in
> DAMON_LRU_SORT and DAMON_SAMPLIE_MTIER.  It forgot to drop that in the
> DAMON sysfs interface.
> 
> Now the zero target_value check in DAMON sysfs interface is only
> redundant.  Further, it has a time-of-check to time-of-use (toctou) race
> with target_value_store().  It can confuse readers to believe [1] the
> division-by-zero can still happen.  Drop the redundant and racy check.
> 
> [1] https://lore.kernel.org/20261021005234.94107-1-sj@kernel.org
> 
> Signed-off-by: SJ Park <sj@kernel.org>

Sashiko has reviewed this patch and found no issues.

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