[ 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 -1. The handle field of any page that was not
successfully mapped will be -1, so this catches all cases where
unmapping can legitimately fail.
Suggested-by: Juergen Gross <jgross@xxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Demi Marie Obenour <demi@xxxxxxxxxxxxxxxxxxxxxx>
Fixes: 73e9e72247b9 ("xen/gntdev: Avoid blocking in unmap_grant_pages()")
---
drivers/xen/gntdev.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 492084814f55d8ed46d2d656db75b28a91dd7f06..27d955c5d9f9076266f77b9fedfa1a6a2ba08f56 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -416,7 +416,8 @@ 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 &&
+ map->unmap_ops[offset+i].handle != -1);
pr_debug("unmap handle=%d st=%d\n",
map->unmap_ops[offset+i].handle,
map->unmap_ops[offset+i].status);
--
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab
