On 11.07.22 00:54, Demi Marie Obenour wrote:
Hello Demi Marie
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.
Suggested-by: Juergen Gross jgross@suse.com Reviewed-by: Oleksandr Tyshchenko oleksandr_tyshchenko@epam.com Cc: stable@vger.kernel.org Signed-off-by: Demi Marie Obenour demi@invisiblethingslab.com Fixes: dbe97cff7dd9 ("xen/gntdev: Avoid blocking in unmap_grant_pages()")
Next time please add a changelog, also I assume current patch ought to be v2 instead of v10)
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 4b56c39f766d4da68570d08d963f6ef40c8d9c37..44a1078da21b8a2333b4432900a8dbdfb8e13c53 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->kunmap_ops[offset + i].status != GNTST_okay &&map->kunmap_ops[offset + i].handle != INVALID_GRANT_HANDLE);
s/kunmap_ops/unmap_ops
[snip]