From b00c53e8f411a0b2be036c41852c6858541afbf7 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 20 Apr 2017 16:40:36 -0600 Subject: blk-mq: fix schedule-while-atomic with scheduler attached We must have dropped the ctx before we call blk_mq_sched_insert_request() with can_block=true, otherwise we risk that a flush request can block on insertion if we are currently out of tags. [ 47.667190] BUG: scheduling while atomic: jbd2/sda2-8/2089/0x00000002 [ 47.674493] Modules linked in: x86_pkg_temp_thermal btrfs xor zlib_deflate raid6_pq sr_mod cdre [ 47.690572] Preemption disabled at: [ 47.690584] [] blk_mq_sched_get_request+0x6c/0x280 [ 47.701764] CPU: 1 PID: 2089 Comm: jbd2/sda2-8 Not tainted 4.11.0-rc7+ #271 [ 47.709630] Hardware name: Dell Inc. PowerEdge T630/0NT78X, BIOS 2.3.4 11/09/2016 [ 47.718081] Call Trace: [ 47.720903] dump_stack+0x4f/0x73 [ 47.724694] ? blk_mq_sched_get_request+0x6c/0x280 [ 47.730137] __schedule_bug+0x6c/0xc0 [ 47.734314] __schedule+0x559/0x780 [ 47.738302] schedule+0x3b/0x90 [ 47.741899] io_schedule+0x11/0x40 [ 47.745788] blk_mq_get_tag+0x167/0x2a0 [ 47.750162] ? remove_wait_queue+0x70/0x70 [ 47.754901] blk_mq_get_driver_tag+0x92/0xf0 [ 47.759758] blk_mq_sched_insert_request+0x134/0x170 [ 47.765398] ? blk_account_io_start+0xd0/0x270 [ 47.770679] blk_mq_make_request+0x1b2/0x850 [ 47.775766] generic_make_request+0xf7/0x2d0 [ 47.780860] submit_bio+0x5f/0x120 [ 47.784979] ? submit_bio+0x5f/0x120 [ 47.789631] submit_bh_wbc.isra.46+0x10d/0x130 [ 47.794902] submit_bh+0xb/0x10 [ 47.798719] journal_submit_commit_record+0x190/0x210 [ 47.804686] ? _raw_spin_unlock+0x13/0x30 [ 47.809480] jbd2_journal_commit_transaction+0x180a/0x1d00 [ 47.815925] kjournald2+0xb6/0x250 [ 47.820022] ? kjournald2+0xb6/0x250 [ 47.824328] ? remove_wait_queue+0x70/0x70 [ 47.829223] kthread+0x10e/0x140 [ 47.833147] ? commit_timeout+0x10/0x10 [ 47.837742] ? kthread_create_on_node+0x40/0x40 [ 47.843122] ret_from_fork+0x29/0x40 Fixes: a4d907b6a33b ("blk-mq: streamline blk_mq_make_request") Reviewed-by: Omar Sandoval Signed-off-by: Jens Axboe --- block/blk-mq.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'block/blk-mq.c') diff --git a/block/blk-mq.c b/block/blk-mq.c index 9d7645f24b05..47b810638729 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1571,6 +1571,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) plug = current->plug; if (unlikely(is_flush_fua)) { + blk_mq_put_ctx(data.ctx); blk_mq_bio_to_request(rq, bio); if (q->elevator) { blk_mq_sched_insert_request(rq, false, true, true, @@ -1582,6 +1583,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) } else if (plug && q->nr_hw_queues == 1) { struct request *last = NULL; + blk_mq_put_ctx(data.ctx); blk_mq_bio_to_request(rq, bio); /* @@ -1626,20 +1628,19 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) if (same_queue_rq) blk_mq_try_issue_directly(data.hctx, same_queue_rq, &cookie); - - return cookie; } else if (q->nr_hw_queues > 1 && is_sync) { blk_mq_put_ctx(data.ctx); blk_mq_bio_to_request(rq, bio); blk_mq_try_issue_directly(data.hctx, rq, &cookie); - return cookie; } else if (q->elevator) { + blk_mq_put_ctx(data.ctx); blk_mq_bio_to_request(rq, bio); blk_mq_sched_insert_request(rq, false, true, true, true); - } else if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) + } else if (!blk_mq_merge_queue_io(data.hctx, data.ctx, rq, bio)) { + blk_mq_put_ctx(data.ctx); blk_mq_run_hw_queue(data.hctx, true); + } - blk_mq_put_ctx(data.ctx); return cookie; } -- cgit v1.2.3