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@suse.com Cc: stable@vger.kernel.org Signed-off-by: Demi Marie Obenour demi@invisiblethingslab.com Fixes: 79963021fd71 ("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 f415c056ff8ab8d808ee2bacfaa3cad57af28204..54fee4087bf1078803c230ad2081aafa8415cf53 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -401,7 +401,8 @@ 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);