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From:   David Howells <dhowells@redhat.com>
To:     Jens Axboe <axboe@kernel.dk>, David Hildenbrand <david@redhat.com>,
        kernel test robot <oliver.sang@intel.com>
cc:     dhowells@redhat.com, Christoph Hellwig <hch@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Matthew Wilcox <willy@infradead.org>, Jan Kara <jack@suse.cz>,
        Jeff Layton <jlayton@kernel.org>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Logan Gunthorpe <logang@deltatee.com>,
        Hillf Danton <hdanton@sina.com>,
        Christian Brauner <brauner@kernel.org>,
        Lorenzo Stoakes <lstoakes@gmail.com>,
        linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
        linux-mm@kvack.org, oe-lkp@lists.linux.dev, lkp@intel.com,
        linux-kernel@vger.kernel.org
Subject: [PATCH] block: Fix dio_bio_alloc() to set BIO_PAGE_PINNED
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Date:   Mon, 12 Jun 2023 17:51:21 +0100
Message-ID: <431929.1686588681@warthog.procyon.org.uk>
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    =

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, openin=
g
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@i=
ntel.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 =3D 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 =3D bio;
 	sdio->logical_offset_in_bio =3D sdio->cur_page_fs_offset;
 }