FAILED: patch "[PATCH] xen/gntdev: Ignore failure to unmap INVALID_GRANT_HANDLE" failed to apply to 5.4-stable tree

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 166d3863231667c4f64dee72b77d1102cdfad11f Mon Sep 17 00:00:00 2001
From: Demi Marie Obenour <[email protected]>
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.

index 4b56c39f766d..84b143eef395 100644
@@ -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);