From b18fdfb00838594b669749e8f2f622c5df1e43ad Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Thu, 17 Feb 2022 23:40:02 -0500 Subject: [PATCH] dm: interlock pending dm_io and dm_wait_for_bios_completion 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 Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Mikulas Patocka Reviewed-by: Mike Snitzer Signed-off-by: Greg Kroah-Hartman --- drivers/md/dm.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 31d02e91e2be8..d2ee97cd7d14e 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2475,6 +2475,8 @@ static int dm_wait_for_completion(struct mapped_device *md, long task_state) } finish_wait(&md->wait, &wait); + smp_rmb(); /* paired with atomic_dec_return in end_io_acct */ + return r; }