On Sun, May 16, 2021 at 04:03:28PM +0100, Matthew Wilcox (Oracle) wrote:

From: Christoph Hellwig <hch@lst.de>

commit 1cea335d1db1ce6ab71b3d2f94a807112b738a0f upstream

bio completions can race when a page spans more than one file system
block.  Add a spinlock to synchronize marking the page uptodate.

Fixes: 9dc55f1389f9 ("iomap: add support for sub-pagesize buffered I/O without buffer heads")
Reported-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <redacted>
Reviewed-by: Darrick J. Wong <redacted>
Signed-off-by: Darrick J. Wong <redacted>
---
 fs/iomap/buffered-io.c | 34 ++++++++++++++++++++++++----------
 include/linux/iomap.h  |  1 +
 2 files changed, 25 insertions(+), 10 deletions(-)

No s-o-b from you as you did the backport?  :(

Anyway, what about a 4.19.y version?

thanks,

greg k-h