diff options
authorMike Snitzer <>2022-02-17 23:40:02 -0500
committerGreg Kroah-Hartman <>2022-05-12 12:23:50 +0200
commit786dc86c84348536c77995873a319d98feb49988 (patch)
parentad1393b92e5059218d055bfec8f4946d85ad04c4 (diff)
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: 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 <>
1 files changed, 7 insertions, 3 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 6fd2899a362a..37b8bb4d80f0 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -681,14 +681,16 @@ static void end_io_acct(struct mapped_device *md, struct bio *bio,
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)))
@@ -2494,6 +2496,8 @@ static int dm_wait_for_completion(struct mapped_device *md, long task_state)
finish_wait(&md->wait, &wait);
+ smp_rmb();
return r;