From: Mike Snitzer snitzer@redhat.com
commit 9f6dc633761006f974701d4c88da71ab68670749 upstream.
Commit d208b89401e0 ("dm: fix mempool NULL pointer race when completing IO") didn't go far enough.
When bio_end_io_acct ends the count of in-flight I/Os may reach zero and the DM device may be suspended. There is a possibility that the suspend races with dm_stats_account_io.
Fix this by adding percpu "pending_io" counters to track outstanding dm_io. Move kicking of suspend queue to dm_io_dec_pending(). Also, rename md_in_flight_bios() to dm_in_flight_bios() and update it to iterate all pending_io counters.
Fixes: d208b89401e0 ("dm: fix mempool NULL pointer race when completing IO") Cc: stable@vger.kernel.org Co-developed-by: Mikulas Patocka mpatocka@redhat.com Signed-off-by: Mikulas Patocka mpatocka@redhat.com Signed-off-by: Mike Snitzer snitzer@redhat.com Signed-off-by: Mikulas Patocka mpatocka@redhat.com Reviewed-by: Mike Snitzer snitzer@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/md/dm.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2475,6 +2475,8 @@ static int dm_wait_for_completion(struct } finish_wait(&md->wait, &wait);
+ smp_rmb(); /* paired with atomic_dec_return in end_io_acct */ + return r; }