Re: [PATCH 6.6.y] mm/damon/core: don't skip damos_adjust_quota() while esz is not zero

[SJ Park <sj@kernel.org>]

On Sat, 03 Oct 2026 17:56:16 +0000 sashiko-bot@kernel.org wrote:

> Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
> - [Medium] mm: commit message references nonexistent damos_quota_is_set()
> - [Low] mm: outdated comment for damos_set_effective_quota()
> --
> 
> commit bdd4b48218af232c248d2db96f0af460e859f59e
> Author: SJ Park <sj@kernel.org>
> 
> mm/damon/core: don't skip damos_adjust_quota() while esz is not zero
> 
> DAMOS could unexpectedly stop working when a user disables quota using the
> online parameters commit feature. Fix it by correcting a wrong quota
> unset check in damos_adjust_quota().
> 
> Link: https://lore.kernel.org/20260916135020.86483-1-sj@kernel.org
> 
> > Other logic for catching that uses damos_quota_is_set(), which understands
> > the fact and therefore checks the effective size quota in addition to the
> > user setup.  Fix the issue by using damos_quota_is_set() in
> > damos_adjust_quota() to determine if its works should be skipped.
> 
> [Severity: Medium]
> The commit message states the fix uses damos_quota_is_set(). However, the
> code below checks the fields directly inline. Should the commit message
> be updated to reflect the inline check?

No, since this is a backporting of the mainline commit.

> 
> > diff --git a/mm/damon/core.c b/mm/damon/core.c
> > index fe91b296f4c66..bd46a63b611cf 100644
> > --- a/mm/damon/core.c
> > +++ b/mm/damon/core.c
> > @@ -1087,7 +1087,7 @@ static void damos_adjust_quota(struct damon_ctx *c, struct damos *s)
> >  	unsigned long cumulated_sz;
> >  	unsigned int score, max_score = 0;
> >  
> > -	if (!quota->ms && !quota->sz)
> > +	if (!quota->esz && !quota->ms && !quota->sz)
> >  		return;
> 
> [Severity: Low]
> With this change, damos_adjust_quota() can proceed even when quota->ms and
> quota->sz are zero. This allows damos_set_effective_quota() to be called
> later in the function during a new charge window:
> 
> 	if (!time_in_range_open(...)) {
> 		...
> 		damos_set_effective_quota(quota);
> 	}
> 
> Does this make the comment above damos_set_effective_quota() outdated? It
> currently states:
> 
> /* Shouldn't be called if quota->ms and quota->sz are zero */
> static void damos_set_effective_quota(struct damos_quota *quota)

That's out of the scope of this backport in my opinion.

> 
> -- 
> Sashiko AI review · https://sashiko.dev/#/patchset/20261003154818.24786-1-sj@kernel.org?part=1


Thanks,
SJ