| Message ID | 431929.1686588681@warthog.procyon.org.uk (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | block: Fix dio_bio_alloc() to set BIO_PAGE_PINNED | expand |
On 12.06.23 18:51, David Howells wrote: > > Fix dio_bio_alloc() to set BIO_PAGE_PINNED, not BIO_PAGE_REFFED, so that > the bio code unpins the pinned pages rather than putting a ref on them. > > The issue was causing: > > WARNING: CPU: 6 PID: 2220 at mm/gup.c:76 try_get_folio > > This can be caused by creating a file on a loopback UDF filesystem, opening > it O_DIRECT and making two writes to it from the same source buffer. > > Fixes: 1ccf164ec866 ("block: Use iov_iter_extract_pages() and page pinning in direct-io.c") > Reported-by: kernel test robot <oliver.sang@intel.com> > Closes: https://lore.kernel.org/oe-lkp/202306120931.a9606b88-oliver.sang@intel.com > Signed-off-by: David Howells <dhowells@redhat.com> > cc: Christoph Hellwig <hch@infradead.org> > cc: David Hildenbrand <david@redhat.com> > cc: Andrew Morton <akpm@linux-foundation.org> > cc: Jens Axboe <axboe@kernel.dk> > cc: Al Viro <viro@zeniv.linux.org.uk> > cc: Matthew Wilcox <willy@infradead.org> > cc: Jan Kara <jack@suse.cz> > cc: Jeff Layton <jlayton@kernel.org> > cc: Jason Gunthorpe <jgg@nvidia.com> > cc: Logan Gunthorpe <logang@deltatee.com> > cc: Hillf Danton <hdanton@sina.com> > cc: Christian Brauner <brauner@kernel.org> > cc: Linus Torvalds <torvalds@linux-foundation.org> > cc: linux-fsdevel@vger.kernel.org > cc: linux-block@vger.kernel.org > cc: linux-kernel@vger.kernel.org > cc: linux-mm@kvack.org > --- > fs/direct-io.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/direct-io.c b/fs/direct-io.c > index 14049204cac8..04e810826ee8 100644 > --- a/fs/direct-io.c > +++ b/fs/direct-io.c > @@ -415,7 +415,8 @@ dio_bio_alloc(struct dio *dio, struct dio_submit *sdio, > else > bio->bi_end_io = dio_bio_end_io; > /* for now require references for all pages */ Does the comment still hold? > - bio_set_flag(bio, BIO_PAGE_REFFED); > + if (dio->need_unpin) > + bio_set_flag(bio, BIO_PAGE_PINNED); > sdio->bio = bio; > sdio->logical_offset_in_bio = sdio->cur_page_fs_offset; > } >
David Hildenbrand <david@redhat.com> wrote: > > /* for now require references for all pages */ > > Does the comment still hold? Actually, no. David
Okay, it isn't this. The problem appears to be that __blockdev_direct_IO() calls dio_cleanup() twice if do_direct_IO() fails. David
static inline void dio_cleanup(struct dio *dio, struct dio_submit *sdio)
{
- while (sdio->head < sdio->tail)
- put_page(dio->pages[sdio->head++]);
+ if (dio->is_pinned)
+ unpin_user_pages(dio->pages + sdio->head,
+ sdio->tail - sdio->head);
}
/*
Meh. It's obvious. Need to advance head.
David
diff --git a/fs/direct-io.c b/fs/direct-io.c index 14049204cac8..04e810826ee8 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -415,7 +415,8 @@ dio_bio_alloc(struct dio *dio, struct dio_submit *sdio, else bio->bi_end_io = dio_bio_end_io; /* for now require references for all pages */ - bio_set_flag(bio, BIO_PAGE_REFFED); + if (dio->need_unpin) + bio_set_flag(bio, BIO_PAGE_PINNED); sdio->bio = bio; sdio->logical_offset_in_bio = sdio->cur_page_fs_offset; }
Fix dio_bio_alloc() to set BIO_PAGE_PINNED, not BIO_PAGE_REFFED, so that the bio code unpins the pinned pages rather than putting a ref on them. The issue was causing: WARNING: CPU: 6 PID: 2220 at mm/gup.c:76 try_get_folio This can be caused by creating a file on a loopback UDF filesystem, opening it O_DIRECT and making two writes to it from the same source buffer. Fixes: 1ccf164ec866 ("block: Use iov_iter_extract_pages() and page pinning in direct-io.c") Reported-by: kernel test robot <oliver.sang@intel.com> Closes: https://lore.kernel.org/oe-lkp/202306120931.a9606b88-oliver.sang@intel.com Signed-off-by: David Howells <dhowells@redhat.com> cc: Christoph Hellwig <hch@infradead.org> cc: David Hildenbrand <david@redhat.com> cc: Andrew Morton <akpm@linux-foundation.org> cc: Jens Axboe <axboe@kernel.dk> cc: Al Viro <viro@zeniv.linux.org.uk> cc: Matthew Wilcox <willy@infradead.org> cc: Jan Kara <jack@suse.cz> cc: Jeff Layton <jlayton@kernel.org> cc: Jason Gunthorpe <jgg@nvidia.com> cc: Logan Gunthorpe <logang@deltatee.com> cc: Hillf Danton <hdanton@sina.com> cc: Christian Brauner <brauner@kernel.org> cc: Linus Torvalds <torvalds@linux-foundation.org> cc: linux-fsdevel@vger.kernel.org cc: linux-block@vger.kernel.org cc: linux-kernel@vger.kernel.org cc: linux-mm@kvack.org --- fs/direct-io.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)