On Mon, Jul 1, 2024 at 8:48 PM Ryan Roberts <ryan.roberts@xxxxxxx> wrote: > > On 30/06/2024 00:41, Barry Song wrote: > > From: Barry Song <v-songbaohua@xxxxxxxx> > > > > The optimization of list_empty(&folio->_deferred_list) aimed to prevent > > increasing the PTL duration when a large folio is partially unmapped, > > for example, from subpage 0 to subpage (nr - 2). > > > > But Ryan's commit 5ed890ce5147 ("mm: vmscan: avoid split during > > shrink_folio_list()") actually splits this kind of large folios. This > > makes the "optimization" useless. > > > > Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx> > > Cc: David Hildenbrand <david@xxxxxxxxxx> > > Cc: Ryan Roberts <ryan.roberts@xxxxxxx> > > Reviewed-by: Ryan Roberts <ryan.roberts@xxxxxxx> > > > --- > > -v1 > > * I remember David and Ryan once suggested that this check could be dropped > > while the patch was being pulled into mm-unstable. However, for some reason, > > I forgot to request squashing this change. > > > > mm/vmscan.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index 3d4c681c6d40..0761f91b407f 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -1291,7 +1291,7 @@ static unsigned int shrink_folio_list(struct list_head *folio_list, > > * try_to_unmap acquire PTL from the first PTE, > > * eliminating the influence of temporary PTE values. > > */ > > - if (folio_test_large(folio) && list_empty(&folio->_deferred_list)) > > + if (folio_test_large(folio)) > > As it stands, the list_empty() technically needs a data_race() annotation. I > think your original patch went into v6.10-rc1? If so, perhaps it makes sense to > try to get this into the next rc? Either way is fine. Hi Andrew, if you include it for the next RC, could you please add this tag? Fixes: 73bc32875ee9 ("mm: hold PTL from the first PTE while reclaiming a large folio") And an additional changelog: Additionally, the list_empty() technically requires a data_race() annotation. > > > flags |= TTU_SYNC; > > > > try_to_unmap(folio, flags); > Thanks Barry