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 | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
--- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -681,14 +681,16 @@ static void end_io_acct(struct mapped_de { unsigned long duration = jiffies - start_time;
- generic_end_io_acct(md->queue, bio_op(bio), &dm_disk(md)->part0, - start_time); - if (unlikely(dm_stats_used(&md->stats))) dm_stats_account_io(&md->stats, bio_data_dir(bio), bio->bi_iter.bi_sector, bio_sectors(bio), true, duration, stats_aux);
+ smp_wmb(); + + generic_end_io_acct(md->queue, bio_op(bio), &dm_disk(md)->part0, + start_time); + /* nudge anyone waiting on suspend queue */ if (unlikely(wq_has_sleeper(&md->wait))) wake_up(&md->wait); @@ -2494,6 +2496,8 @@ static int dm_wait_for_completion(struct } finish_wait(&md->wait, &wait);
+ smp_rmb(); + return r; }