Re: [PATCH] mm/madvise: add cond_resched() in THP branch of madvise_cold_or_pageout_pte_range()

[Andrew Morton]

On Sat, 10 Oct 2026 10:26:33 -0400 Gregory Price <gourry@xxxxxxxxxx> wrote:

> > Signed-off-by: Wei Yang <albinwyang@xxxxxxxxxxx>
> > ---
> >  mm/madvise.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/mm/madvise.c b/mm/madvise.c
> > index eeee82cf2b3f..0755e6d99757 100644
> > --- a/mm/madvise.c
> > +++ b/mm/madvise.c
> > @@ -450,6 +450,7 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
> >  		spin_unlock(ptl);
> >  		if (pageout)
> >  			reclaim_pages(&folio_list);
> > +		cond_resched();
> >  		return 0;
> >  	}
> > 
> 
> This same improvement came naturally from refactoring the entire
> function into a proper pagewalk structure:
> 
> https://lore.kernel.org/linux-mm/20260922235830.2350770-10-gourry@xxxxxxxxxx/

I'm thinking

Fixes: 9c276cc65a58 ("mm: introduce MADV_COLD")

Sep 25 2019.  So 5.x and 6.x kernels want this.  Current kernels
actually don't need this because PREEMPT_NONE has virtually
disappeared.  But 99%(?) of machines run 5.x and 6.x.

I'll go with Wei's simple one-liner for backportability & safety. 
Let's look at broader changes in future -rc cycles.