From: Demi Marie Obenour demi@invisiblethingslab.com
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@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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/xen/gntdev.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -393,7 +393,8 @@ 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);