Commit 39b8cdd1 authored Jul 10, 2022 by Demi Marie Obenour Committed by Greg Kroah-Hartman Jul 29, 2022

xen/gntdev: Ignore failure to unmap INVALID_GRANT_HANDLE



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>

parent d2da5392

drivers/xen/gntdev.c

+2 −1

Original line number	Original line	Diff line number	Diff line
	@@ -416,7 +416,8 @@ static void __unmap_grant_pages_done(int result,
	unsigned int offset = data->unmap_ops - map->unmap_ops;		unsigned int offset = data->unmap_ops - map->unmap_ops;

	for (i = 0; i < data->count; i++) {		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",		pr_debug("unmap handle=%d st=%d\n",
	map->unmap_ops[offset+i].handle,		map->unmap_ops[offset+i].handle,
	map->unmap_ops[offset+i].status);		map->unmap_ops[offset+i].status);