"Michael S. Tsirkin" <[email protected]> wrote: > get_user_pages_fast returns number of pages on success, negative value > on failure, but never 0. Fix vhost code to match this logic.
It can return 0 if you ask for 0 pages :) >From the comment: * Returns number of pages pinned. This may be fewer than the number * requested. If nr_pages is 0 or negative, returns 0. If no pages * were pinned, returns -errno. */ I agree that code was wrong, but the BUG_ON() is not neccessary IMHO. The important bit is the change in the comparison. Reviewed-by: Juan Quintela <[email protected]> > Signed-off-by: Michael S. Tsirkin <[email protected]> > --- > drivers/vhost/vhost.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c > index d4f8fdf..d003504 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -646,8 +646,9 @@ static int set_bit_to_user(int nr, void __user *addr) > int bit = nr + (log % PAGE_SIZE) * 8; > int r; > r = get_user_pages_fast(log, 1, 1, &page); > - if (r) > + if (r < 0) > return r; > + BUG_ON(r != 1); > base = kmap_atomic(page, KM_USER0); > set_bit(bit, base); > kunmap_atomic(base, KM_USER0); _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
