From: Demi Marie Obenour <demi@xxxxxxxxxxxxxxxxxxxxxx>
commit 166d3863231667c4f64dee72b77d1102cdfad11f upstream.
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: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/xen/gntdev.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -401,7 +401,8 @@ static void __unmap_grant_pages_done(int
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);
