Patch "xen/gntdev: Ignore failure to unmap INVALID_GRANT_HANDLE" has been added to the 5.18-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    xen/gntdev: Ignore failure to unmap INVALID_GRANT_HANDLE

to the 5.18-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     xen-gntdev-ignore-failure-to-unmap-invalid_grant_han.patch
and it can be found in the queue-5.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 731723087ad30c6d0e95429eff51c8d6e9a8f0d0
Author: Demi Marie Obenour <demi@xxxxxxxxxxxxxxxxxxxxxx>
Date:   Sun Jul 10 19:05:22 2022 -0400

    xen/gntdev: Ignore failure to unmap INVALID_GRANT_HANDLE
    
    [ Upstream commit 166d3863231667c4f64dee72b77d1102cdfad11f ]
    
    The error paths of gntdev_mmap() can call unmap_grant_pages() even
    though not all of the pages have been successfully mapped.  This will
    trigger the WARN_ON()s in __unmap_grant_pages_done().  The number of
    warnings can be very large; I have observed thousands of lines of
    warnings in the systemd journal.
    
    Avoid this problem by only warning on unmapping failure if the handle
    being unmapped is not INVALID_GRANT_HANDLE.  The handle field of any
    page that was not successfully mapped will be INVALID_GRANT_HANDLE, so
    this catches all cases where unmapping can legitimately fail.
    
    Fixes: dbe97cff7dd9 ("xen/gntdev: Avoid blocking in unmap_grant_pages()")
    Cc: stable@xxxxxxxxxxxxxxx
    Suggested-by: Juergen Gross <jgross@xxxxxxxx>
    Signed-off-by: Demi Marie Obenour <demi@xxxxxxxxxxxxxxxxxxxxxx>
    Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
    Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
    Link: https://lore.kernel.org/r/20220710230522.1563-1-demi@xxxxxxxxxxxxxxxxxxxxxx
    Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 4b56c39f766d..84b143eef395 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -396,13 +396,15 @@ static void __unmap_grant_pages_done(int result,
 	unsigned int offset = data->unmap_ops - map->unmap_ops;
 
 	for (i = 0; i < data->count; i++) {
-		WARN_ON(map->unmap_ops[offset+i].status);
+		WARN_ON(map->unmap_ops[offset + i].status != GNTST_okay &&
+			map->unmap_ops[offset + i].handle != INVALID_GRANT_HANDLE);
 		pr_debug("unmap handle=%d st=%d\n",
 			map->unmap_ops[offset+i].handle,
 			map->unmap_ops[offset+i].status);
 		map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
 		if (use_ptemod) {
-			WARN_ON(map->kunmap_ops[offset+i].status);
+			WARN_ON(map->kunmap_ops[offset + i].status != GNTST_okay &&
+				map->kunmap_ops[offset + i].handle != INVALID_GRANT_HANDLE);
 			pr_debug("kunmap handle=%u st=%d\n",
 				 map->kunmap_ops[offset+i].handle,
 				 map->kunmap_ops[offset+i].status);