Re: [fuse-devel] fuse: trying to steal weird page

[Miklos Szeredi <miklos@szeredi.hu>]

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On Mon, Feb 25, 2019 at 10:41 PM Nikolaus Rath <Nikolaus@rath.org> wrote:
>
> On Feb 12 2019, Nikolaus Rath <Nikolaus@rath.org> wrote:
> > On Feb 12 2019, Miklos Szeredi <miklos@szeredi.hu> wrote:
> >> On Sun, Feb 10, 2019 at 11:05 PM Nikolaus Rath <Nikolaus@rath.org> wrote:
> >>
> >>> Bad news. I can now reliably reproduce the issue again.
> >>
> >> A reliable reproducer is always good news.   Are the messages exactly
> >> the same as last time (value of flags, etc)?
> >
> > The flags, count, mapcount and mapping values are always the same. The
> > page and index is varying. So the general format is:
> >
> > [ 2562.773181] fuse: trying to steal weird page
> > [ 2562.773187] page=<something> index=<something>
> > flags=17ffffc00000ad, count=1, mapcount=0, mapping= (null)
>
> Is there anything else I can do to help debugging this?

Could you please try the attached patch?

Thanks,
Miklos

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diff --git a/fs/splice.c b/fs/splice.c
index de2ede048473..07c5c77abc45 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -73,7 +73,7 @@ static int page_cache_pipe_buf_steal(struct pipe_inode_info *pipe,
 		 * If we succeeded in removing the mapping, set LRU flag
 		 * and return good.
 		 */
-		if (remove_mapping(mapping, page)) {
+		if (remove_mapping(mapping, page) && page_count(page) == 1) {
 			buf->flags |= PIPE_BUF_FLAG_LRU;
 			return 0;
 		}