Re: [PATCH] block: save irq state in blkg_lookup_create()
From: Dennis Zhou <dennis@kernel.org>
Date: 2018-12-19 19:45:00
On Thu, Dec 20, 2018 at 12:29:15AM +0800, Ming Lei wrote:
quoted hunk ↗ jump to hunk
blkg_lookup_create() may be called from pool_map() in which irq state is saved, so we have to do that in blkg_lookup_create(). Otherwise, the following lockdep warning can be triggered: [ 104.258537] ================================ [ 104.259129] WARNING: inconsistent lock state [ 104.259725] 4.20.0-rc6+ #545 Not tainted [ 104.260268] -------------------------------- [ 104.260865] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. [ 104.261727] swapper/49/0 [HC0[0]:SC1[1]:HE0:SE0] takes: [ 104.262444] 00000000db365b5d (&(&pool->lock)->rlock#3){+.?.}, at: thin_endio+0xcf/0x2a3 [dm_thin_pool] [ 104.263747] {SOFTIRQ-ON-W} state was registered at: [ 104.264417] _raw_spin_unlock_irq+0x29/0x4c [ 104.265014] blkg_lookup_create+0xdc/0xe6 [ 104.265609] bio_associate_blkg_from_css+0xd3/0x13f [ 104.266312] bio_associate_blkg+0x15a/0x1bb [ 104.266913] pool_map+0xe8/0x103 [dm_thin_pool] [ 104.267572] __map_bio+0x98/0x29c [dm_mod] [ 104.268162] __split_and_process_non_flush+0x29e/0x306 [dm_mod] [ 104.269003] __split_and_process_bio+0x16a/0x25b [dm_mod] [ 104.269971] __dm_make_request.isra.14+0xdc/0x124 [dm_mod] [ 104.270973] generic_make_request+0x3f5/0x68b [ 104.271676] process_prepared_mapping+0x166/0x1ef [dm_thin_pool] [ 104.272531] schedule_zero+0x239/0x273 [dm_thin_pool] [ 104.273245] process_cell+0x60c/0x6f1 [dm_thin_pool] [ 104.273967] do_worker+0x60c/0xca8 [dm_thin_pool] [ 104.274635] process_one_work+0x4eb/0x834 [ 104.275203] worker_thread+0x318/0x484 [ 104.275740] kthread+0x1d1/0x1e1 [ 104.276203] ret_from_fork+0x3a/0x50 [ 104.276714] irq event stamp: 170003 [ 104.277201] hardirqs last enabled at (170002): [<ffffffff81bcc33e>] _raw_spin_unlock_irqrestore+0x44/0x6b [ 104.278535] hardirqs last disabled at (170003): [<ffffffff81bcc1ad>] _raw_spin_lock_irqsave+0x20/0x55 [ 104.280273] softirqs last enabled at (169978): [<ffffffff810d13d4>] irq_enter+0x4c/0x73 [ 104.281617] softirqs last disabled at (169979): [<ffffffff810d1479>] irq_exit+0x7e/0x11d [ 104.282744] [ 104.282744] other info that might help us debug this: [ 104.283640] Possible unsafe locking scenario: [ 104.283640] [ 104.284452] CPU0 [ 104.284803] ---- [ 104.285150] lock(&(&pool->lock)->rlock#3); [ 104.285762] <Interrupt> [ 104.286130] lock(&(&pool->lock)->rlock#3); [ 104.286750] [ 104.286750] *** DEADLOCK *** [ 104.286750] [ 104.287564] no locks held by swapper/49/0. [ 104.288129] [ 104.288129] stack backtrace: [ 104.288738] CPU: 49 PID: 0 Comm: swapper/49 Not tainted 4.20.0-rc6+ #545 [ 104.289700] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-2.fc27 04/01/2014 [ 104.290858] Call Trace: [ 104.291204] <IRQ> [ 104.291502] dump_stack+0x9a/0xe6 [ 104.291968] mark_lock+0x56c/0x7a6 [ 104.292442] ? check_usage_backwards+0x209/0x209 [ 104.293086] __lock_acquire+0x400/0x15bf [ 104.293662] ? check_chain_key+0x150/0x1aa [ 104.294236] lock_acquire+0x1a6/0x1e3 [ 104.294768] ? thin_endio+0xcf/0x2a3 [dm_thin_pool] [ 104.295444] ? _raw_spin_unlock_irqrestore+0x44/0x6b [ 104.296143] ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool] [ 104.297031] _raw_spin_lock_irqsave+0x46/0x55 [ 104.297659] ? thin_endio+0xcf/0x2a3 [dm_thin_pool] [ 104.298335] thin_endio+0xcf/0x2a3 [dm_thin_pool] [ 104.298997] ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool] [ 104.299886] ? check_flags+0x20a/0x20a [ 104.300408] ? lock_acquire+0x1a6/0x1e3 [ 104.300954] ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool] [ 104.301865] clone_endio+0x1bb/0x22d [dm_mod] [ 104.302491] ? disable_write_zeroes+0x20/0x20 [dm_mod] [ 104.303200] ? bio_disassociate_blkg+0xc6/0x15f [ 104.303836] ? bio_endio+0x2b2/0x2da [ 104.304349] clone_endio+0x1f3/0x22d [dm_mod] [ 104.304978] ? disable_write_zeroes+0x20/0x20 [dm_mod] [ 104.305709] ? bio_disassociate_blkg+0xc6/0x15f [ 104.306333] ? bio_endio+0x2b2/0x2da [ 104.306853] clone_endio+0x1f3/0x22d [dm_mod] [ 104.307476] ? disable_write_zeroes+0x20/0x20 [dm_mod] [ 104.308185] ? bio_disassociate_blkg+0xc6/0x15f [ 104.308817] ? bio_endio+0x2b2/0x2da [ 104.309319] blk_update_request+0x2de/0x4cc [ 104.309927] blk_mq_end_request+0x2a/0x183 [ 104.310498] blk_done_softirq+0x16a/0x1a6 [ 104.311051] ? blk_softirq_cpu_dead+0xe2/0xe2 [ 104.311653] ? __lock_is_held+0x2a/0x87 [ 104.312186] __do_softirq+0x250/0x4e8 [ 104.312705] irq_exit+0x7e/0x11d [ 104.313157] call_function_single_interrupt+0xf/0x20 [ 104.313860] </IRQ> [ 104.314163] RIP: 0010:native_safe_halt+0x2/0x3 [ 104.314792] Code: 63 02 df f0 83 44 24 fc 00 48 89 df e8 cc 3f 7a ff 48 8b 03 a8 08 74 0b 65 81 25 9d 31 45 7e ff ff ff 7f 5b 5d 41 5c c3 fb f4 <c3> f4 c3 0f 1f 44 00 00 41 56 41 55 41 54 55 53 e8 a2 0d 5c ff e8 [ 104.317339] RSP: 0018:ffff888106c9fdc0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff04 [ 104.318390] RAX: 1ffff11020d92100 RBX: 0000000000000000 RCX: ffffffff81159ac7 [ 104.319366] RDX: 1ffffffff05d5e69 RSI: 0000000000000007 RDI: ffff888106c90d1c [ 104.320339] RBP: 0000000000000000 R08: dffffc0000000000 R09: 0000000000000001 [ 104.321313] R10: ffffed1025d57ba0 R11: ffffed1025d57b9f R12: 1ffff11020d93fbf [ 104.322328] R13: 0000000000000031 R14: ffff888106c90040 R15: 0000000000000000 [ 104.323307] ? lockdep_hardirqs_on+0x26b/0x278 [ 104.323927] default_idle+0xd9/0x1a8 [ 104.324427] do_idle+0x162/0x2b2 [ 104.324891] ? arch_cpu_idle_exit+0x28/0x28 [ 104.325467] ? mark_held_locks+0x28/0x7f [ 104.326031] ? _raw_spin_unlock_irqrestore+0x44/0x6b [ 104.326719] cpu_startup_entry+0x1d/0x1f [ 104.327261] start_secondary+0x2cb/0x308 [ 104.327806] ? set_cpu_sibling_map+0x8a3/0x8a3 [ 104.328421] secondary_startup_64+0xa4/0xb0 Fixes: b978962ad4f7f9 ("blkcg: update blkg_lookup_create() to do locking") Cc: Mike Snitzer <redacted> Cc: Dennis Zhou <dennis@kernel.org> Signed-off-by: Ming Lei <redacted> --- block/blk-cgroup.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index c30661ddc873..c8cc1cbb6370 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c@@ -359,9 +359,11 @@ struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, struct blkcg_gq *blkg = blkg_lookup(blkcg, q); if (unlikely(!blkg)) { - spin_lock_irq(&q->queue_lock); + unsigned long flags; + + spin_lock_irqsave(&q->queue_lock, flags); blkg = __blkg_lookup_create(blkcg, q); - spin_unlock_irq(&q->queue_lock); + spin_unlock_irqrestore(&q->queue_lock, flags); } return blkg;-- 2.9.5
Acked-by: Dennis Zhou <dennis@kernel.org> I know it's already applied, but thanks Ming for helping me debug the blkg series. Thanks, Dennis