From: Demi Marie Obenour <demi@xxxxxxxxxxxxxxxxxxxxxx>
[ 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>
---
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);
--
2.35.1
