On Fri, 28 Apr 2023 14:41:40 +0200 Jan Kara <jack@xxxxxxx> wrote: > If the page is pinned, there's no point in trying to reclaim it. > Furthermore if the page is from the page cache we don't want to reclaim > fs-private data from the page because the pinning process may be writing > to the page at any time and reclaiming fs private info on a dirty page > can upset the filesystem (see link below). Obviously I'll add a cc:stable here. I'm suspecting it's so old that there's no real Fixes: target that makes sense? > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1901,6 +1901,16 @@ static unsigned int shrink_folio_list(struct list_head *folio_list, > } > } > > + /* > + * Folio is unmapped now so it cannot be newly pinned anymore. > + * No point in trying to reclaim folio if it is pinned. > + * Furthermore we don't want to reclaim underlying fs metadata > + * if the folio is pinned and thus potentially modified by the > + * pinning process as that may upset the filesystem. > + */ > + if (folio_maybe_dma_pinned(folio)) > + goto activate_locked; > + So I expect the -stable maintainers will be looking for a pre-folios version of this when the time comes.
