Re: [PATCH] mm: don't be stuck to rmap lock on reclaim path

[Matthew Wilcox]

On Tue, May 03, 2022 at 09:30:38PM -0700, Minchan Kim wrote:
> On Wed, May 04, 2022 at 04:32:13AM +0100, Matthew Wilcox wrote:
> > On Tue, May 03, 2022 at 10:03:41AM -0700, Minchan Kim wrote:
> > > -void rmap_walk(struct folio *folio, const struct rmap_walk_control *rwc);
> > > -void rmap_walk_locked(struct folio *folio, const struct rmap_walk_control *rwc);
> > > +void rmap_walk(struct folio *folio, struct rmap_walk_control *rwc);
> > > +void rmap_walk_locked(struct folio *folio, struct rmap_walk_control *rwc);
> > 
> > I see the build bot already beat me to pointing out why this is wrong,
> > but do you not look at git log to figure out why code was changed to be
> > the way it is now, before you change it back?
> 
> This patch added a new field as out param like compact_control so
> the rmap_walk_control is not immutable.

... but we have a user which treats it as if it is.