On Mon, Mar 11, 2019 at 10:52:44AM +0100, Andreas Gruenbacher wrote:

commit 605b0487f0bc1ae9963bf52ece0f5c8055186f81 upstream.

Mark Syms has reported seeing tasks that are stuck waiting in find_insert_glock. It turns out that struct lm_lockname contains four padding bytes on 64-bit architectures that function glock_waitqueue doesn't skip when hashing the glock name. As a result, we can end up waking up the wrong waitqueue, and the waiting tasks may be stuck forever.

Fix that by using ht_parms.key_len instead of sizeof(struct lm_lockname) for the key length.

Reported-by: Mark Syms mark.syms@citrix.com Signed-off-by: Andreas Gruenbacher agruenba@redhat.com Signed-off-by: Bob Peterson rpeterso@redhat.com Cc: stable@vger.kernel.org # v4.14+

---

fs/gfs2/glock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index f66773c71bcde..d32964cd11176 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -107,7 +107,7 @@ static int glock_wake_function(wait_queue_entry_t *wait, unsigned int mode, static wait_queue_head_t *glock_waitqueue(struct lm_lockname *name) {

• u32 hash = jhash2((u32 *)name, sizeof(*name) / 4, 0);

• u32 hash = jhash2((u32 *)name, ht_parms.key_len / 4, 0);

return glock_wait_table + hash_32(hash, GLOCK_WAIT_TABLE_BITS); } -- 2.20.1

Now queued up, thanks.

greg k-h