On 03/26, Chao Yu wrote:
> On 2023/3/24 5:39, Jaegeuk Kim wrote:
> > https://bugzilla.kernel.org/show_bug.cgi?id=216050
> >
> > Somehow we're getting a page which has a different mapping.
> > Let's avoid the infinite loop.
> >
> > Cc: <sta...@vger.kernel.org>
> > Signed-off-by: Jaegeuk Kim <jaeg...@kernel.org>
> > ---
> > fs/f2fs/data.c | 8 ++------
> > 1 file changed, 2 insertions(+), 6 deletions(-)
> >
> > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > index bf51e6e4eb64..80702c93e885 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > @@ -1329,18 +1329,14 @@ struct page *f2fs_get_lock_data_page(struct inode
> > *inode, pgoff_t index,
> > {
> > struct address_space *mapping = inode->i_mapping;
> > struct page *page;
> > -repeat:
> > +
> > page = f2fs_get_read_data_page(inode, index, 0, for_write, NULL);
> > if (IS_ERR(page))
> > return page;
> > /* wait for read completion */
> > lock_page(page);
> > - if (unlikely(page->mapping != mapping)) {
>
> How about using such logic only for move_data_page() to limit affect for
> other paths?
Why move_data_page() only? If this happens, we'll fall into a loop in anywhere?
>
> Jaegeuk, any thoughts about why mapping is mismatch in between page's one and
> inode->i_mapping?
>
> After several times code review, I didn't get any clue about why f2fs always
> get the different mapping in a loop.
I couldn't find the path to happen this. So weird. Please check the history in
the
bug.
>
> Maybe we can loop MM guys to check whether below folio_file_page() may return
> page which has different mapping?
Matthew may have some idea on this?
>
> struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
> int fgp_flags, gfp_t gfp)
> {
> struct folio *folio;
>
> folio = __filemap_get_folio(mapping, index, fgp_flags, gfp);
> if (IS_ERR(folio))
> return NULL;
> return folio_file_page(folio, index);
> }
>
> Thanks,
>
> > - f2fs_put_page(page, 1);
> > - goto repeat;
> > - }
> > - if (unlikely(!PageUptodate(page))) {
> > + if (unlikely(page->mapping != mapping || !PageUptodate(page))) {
> > f2fs_put_page(page, 1);
> > return ERR_PTR(-EIO);
> > }
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