Patch-mainline: v5.19-rc7

Git-commit: 166d3863231667c4f64dee72b77d1102cdfad11f

References: git-fixes

From: Demi Marie Obenour <demi@invisiblethingslab.com>

Date: Sun, 10 Jul 2022 19:05:22 -0400

Subject: [PATCH] xen/gntdev: Ignore failure to unmap INVALID_GRANT_HANDLE

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@vger.kernel.org

Suggested-by: Juergen Gross <jgross@suse.com>

Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>

Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

Reviewed-by: Juergen Gross <jgross@suse.com>

Link: https://lore.kernel.org/r/20220710230522.1563-1-demi@invisiblethingslab.com

Signed-off-by: Juergen Gross <jgross@suse.com>

---

 drivers/xen/gntdev.c | 6 ++++--

 1 file changed, 4 insertions(+), 2 deletions(-)

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);

-- 

2.35.3