Re: [PATCH 1/7] mm/damon/api: introduce DAMOS_FILTER_TYPE_PROBE_HITS_WSUM

[SJ Park <sj@kernel.org>]

On Thu, 10 Sep 2026 14:27:17 +0000 sashiko-bot@kernel.org wrote:

> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Low] The kerneldoc comment for `enum damos_filter_type` leaves the handling behavior of `DAMOS_FILTER_TYPE_PROBE_HITS_WSUM` unexplained and contradictory.
> --
> 
> commit 78a988db300660b08e965cf2117e7ad015861252
> Author: SJ Park <sj@kernel.org>
> Subject: mm/damon/api: introduce DAMOS_FILTER_TYPE_PROBE_HITS_WSUM
> 
> This commit introduces the DAMOS_FILTER_TYPE_PROBE_HITS_WSUM filter type
> to allow API callers to target regions based on their probe_hits weighted
> sum. It also updates the damos_filter structure and associated
> documentation to accommodate this new filter.
> 
> > diff --git a/include/linux/damon.h b/include/linux/damon.h
> > index 871d26adf6ae5..ef99ff778ae10 100644
> > --- a/include/linux/damon.h
> > +++ b/include/linux/damon.h
> > @@ -399,14 +399,15 @@ struct damos_stat {
> >   * @DAMOS_FILTER_TYPE_UNMAPPED:	Unmapped pages.
> >   * @DAMOS_FILTER_TYPE_ADDR:	Address range.
> >   * @DAMOS_FILTER_TYPE_TARGET:	Data Access Monitoring target.
> > + * @DAMOS_FILTER_TYPE_PROBE_HITS_WSUM:	probe_hits weighted sum range.
> >   * @NR_DAMOS_FILTER_TYPES:	Number of filter types.
> >   *
> > - * All types except &DAMOS_FILTER_TYPE_ADDR and &DAMOS_FILTER_TYPE_TARGET
> > - * are handled by the underlying &struct damon_operations as a part of scheme
> > - * action trying, and therefore accounted as 'tried'.  In contrast,
> > - * &DAMOS_FILTER_TYPE_ADDR and &DAMOS_FILTER_TYPE_TARGET filters are handled
> > - * by the core layer before trying of the action, and therefore not accounted
> > - * as 'tried'.
> > + * All types except &DAMOS_FILTER_TYPE_ADDR, &DAMOS_FILTER_TYPE_TARGET and
> > + * &DAMOS_FILTER_TYPE_PROBE_HITS_WSUM are handled by the underlying &struct
> > + * damon_operations as a part of scheme action trying, and therefore accounted
> > + * as 'tried'.  In contrast, &DAMOS_FILTER_TYPE_ADDR and
> > + * &DAMOS_FILTER_TYPE_TARGET filters are handled by the core layer before
> > + * trying of the action, and therefore not accounted as 'tried'.
> 
> [Severity: Low]
> Does this leave the handling behavior of the new filter unexplained?
> 
> The newly updated kerneldoc for enum damos_filter_type explicitly excludes
> DAMOS_FILTER_TYPE_PROBE_HITS_WSUM from the list of filters handled by
> operations, but it appears to be missing from the subsequent sentence
> detailing which filters are handled by the core layer. 
> 
> This creates a contradiction where its handling behavior is undefined. Should
> it be added to the second sentence alongside DAMOS_FILTER_TYPE_ADDR and
> DAMOS_FILTER_TYPE_TARGET?

That's described in the design document.  Maybe we could add more documentation
including reference to the design document.  That could be done as a followup
rather than blocking this patch.

> 
> -- 
> Sashiko AI review · https://sashiko.dev/#/patchset/20260910141849.170896-1-sj@kernel.org?part=1


Thanks,
SJ