raid5_get_active_stripe() can sleep in various situations and it is called by make_stripe_request() while inside the prepare_to_wait()/finish_wait() section. Nested waits like this are not supported. This was noticed while making other changes that add different sleeps to raid5_get_active_stripe() that caused a WARNING with and CONFIG_DEBUG_ATOMIC_SLEEP. No ill effects have been noticed with the code as is, but theoretically a nested and here could cause a dead lock so it should be fixed. To fix this, convert the prepare_to_wait() call to use wake_woken() which supports nested sleeps. Link: https://lwn.net/Articles/628628/ Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx> --- drivers/md/raid5.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index e37ed93d130f..88c22a5cc09a 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -6043,12 +6043,12 @@ static enum stripe_result make_stripe_request(struct mddev *mddev, static bool raid5_make_request(struct mddev *mddev, struct bio * bi) { + DEFINE_WAIT_FUNC(wait, woken_wake_function); struct r5conf *conf = mddev->private; sector_t logical_sector; struct stripe_request_ctx ctx = {}; const int rw = bio_data_dir(bi); enum stripe_result res; - DEFINE_WAIT(w); int s, stripe_cnt; if (unlikely(bi->bi_opf & REQ_PREFLUSH)) { @@ -6111,7 +6111,8 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi) return true; } md_account_bio(mddev, &bi); - prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE); + + add_wait_queue(&conf->wait_for_overlap, &wait); while (1) { res = make_stripe_request(mddev, conf, &ctx, logical_sector, bi); @@ -6134,9 +6135,8 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi) ctx.batch_last = NULL; } - schedule(); - prepare_to_wait(&conf->wait_for_overlap, &w, - TASK_UNINTERRUPTIBLE); + wait_woken(&wait, TASK_UNINTERRUPTIBLE, + MAX_SCHEDULE_TIMEOUT); continue; } @@ -6147,8 +6147,7 @@ static bool raid5_make_request(struct mddev *mddev, struct bio * bi) logical_sector = ctx.first_sector + (s << RAID5_STRIPE_SHIFT(conf)); } - - finish_wait(&conf->wait_for_overlap, &w); + remove_wait_queue(&conf->wait_for_overlap, &wait); if (ctx.batch_last) raid5_release_stripe(ctx.batch_last); -- 2.30.2
