Messages in this thread Patch in this message | | | Date | Mon, 17 Jan 2022 19:06:25 +0300 | From | "Kirill A. Shutemov" <> | Subject | Re: [PATCH 04/12] mm/vmscan: Free non-shmem folios without splitting them |
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On Sun, Jan 16, 2022 at 12:18:14PM +0000, Matthew Wilcox (Oracle) wrote: > We have to allocate memory in order to split a file-backed folio, so > it's not a good idea to split them in the memory freeing path.
Could elaborate on why split a file-backed folio requires memory allocation?
> It also > doesn't work for XFS because pages have an extra reference count from > page_has_private() and split_huge_page() expects that reference to have > already been removed.
Need to adjust can_split_huge_page()?
> Unfortunately, we still have to split shmem THPs > because we can't handle swapping out an entire THP yet.
... especially if the system doesn't have swap :P
> > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > --- > mm/vmscan.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 700434db5735..45665874082d 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1728,8 +1728,8 @@ static unsigned int shrink_page_list(struct list_head *page_list, > /* Adding to swap updated mapping */ > mapping = page_mapping(page); > } > - } else if (unlikely(PageTransHuge(page))) { > - /* Split file THP */ > + } else if (PageSwapBacked(page) && PageTransHuge(page)) { > + /* Split shmem THP */ > if (split_huge_page_to_list(page, page_list)) > goto keep_locked; > } > -- > 2.34.1 >
-- Kirill A. Shutemov
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