sbitmap: silence bogus lockdep IRQ warning
Ming reports that lockdep spews the following trace. What this
essentially says is that the sbitmap swap_lock was used inconsistently
in IRQ enabled and disabled context, and that is usually indicative of a
bug that will cause a deadlock.
For this case, it's a false positive. The swap_lock is used from process
context only, when we swap the bits in the word and cleared mask. We
also end up doing that when we are getting a driver tag, from the
blk_mq_mark_tag_wait(), and from there we hold the waitqueue lock with
IRQs disabled. However, this isn't from an actual IRQ, it's still
process context.
In lieu of a better way to fix this, simply always disable interrupts
when grabbing the swap_lock if lockdep is enabled.
[ 100.967642] ================start test sanity/001================
[ 101.238280] null: module loaded
[ 106.093735]
[ 106.094012] =====================================================
[ 106.094854] WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
[ 106.095759] 4.20.0-rc3_5d2ee7122c73_for-next+ #1 Not tainted
[ 106.096551] -----------------------------------------------------
[ 106.097386] fio/1043 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
[ 106.098231]
000000004c43fa71
(&(&sb->map[i].swap_lock)->rlock){+.+.}, at: sbitmap_get+0xd5/0x22c
[ 106.099431]
[ 106.099431] and this task is already holding:
[ 106.100229]
000000007eec8b2f
(&(&hctx->dispatch_wait_lock)->rlock){....}, at:
blk_mq_dispatch_rq_list+0x4c1/0xd7c
[ 106.101630] which would create a new lock dependency:
[ 106.102326] (&(&hctx->dispatch_wait_lock)->rlock){....} ->
(&(&sb->map[i].swap_lock)->rlock){+.+.}
[ 106.103553]
[ 106.103553] but this new dependency connects a SOFTIRQ-irq-safe lock:
[ 106.104580] (&sbq->ws[i].wait){..-.}
[ 106.104582]
[ 106.104582] ... which became SOFTIRQ-irq-safe at:
[ 106.105751] _raw_spin_lock_irqsave+0x4b/0x82
[ 106.106284] __wake_up_common_lock+0x119/0x1b9
[ 106.106825] sbitmap_queue_wake_up+0x33f/0x383
[ 106.107456] sbitmap_queue_clear+0x4c/0x9a
[ 106.108046] __blk_mq_free_request+0x188/0x1d3
[ 106.108581] blk_mq_free_request+0x23b/0x26b
[ 106.109102] scsi_end_request+0x345/0x5d7
[ 106.109587] scsi_io_completion+0x4b5/0x8f0
[ 106.110099] scsi_finish_command+0x412/0x456
[ 106.110615] scsi_softirq_done+0x23f/0x29b
[ 106.111115] blk_done_softirq+0x2a7/0x2e6
[ 106.111608] __do_softirq+0x360/0x6ad
[ 106.112062] run_ksoftirqd+0x2f/0x5b
[ 106.112499] smpboot_thread_fn+0x3a5/0x3db
[ 106.113000] kthread+0x1d4/0x1e4
[ 106.113457] ret_from_fork+0x3a/0x50
[ 106.113969]
[ 106.113969] to a SOFTIRQ-irq-unsafe lock:
[ 106.114672] (&(&sb->map[i].swap_lock)->rlock){+.+.}
[ 106.114674]
[ 106.114674] ... which became SOFTIRQ-irq-unsafe at:
[ 106.116000] ...
[ 106.116003] _raw_spin_lock+0x33/0x64
[ 106.116676] sbitmap_get+0xd5/0x22c
[ 106.117134] __sbitmap_queue_get+0xe8/0x177
[ 106.117731] __blk_mq_get_tag+0x1e6/0x22d
[ 106.118286] blk_mq_get_tag+0x1db/0x6e4
[ 106.118756] blk_mq_get_driver_tag+0x161/0x258
[ 106.119383] blk_mq_dispatch_rq_list+0x28e/0xd7c
[ 106.120043] blk_mq_do_dispatch_sched+0x23a/0x287
[ 106.120607] blk_mq_sched_dispatch_requests+0x379/0x3fc
[ 106.121234] __blk_mq_run_hw_queue+0x137/0x17e
[ 106.121781] __blk_mq_delay_run_hw_queue+0x80/0x25f
[ 106.122366] blk_mq_run_hw_queue+0x151/0x187
[ 106.122887] blk_mq_sched_insert_requests+0x13f/0x175
[ 106.123492] blk_mq_flush_plug_list+0x7d6/0x81b
[ 106.124042] blk_flush_plug_list+0x392/0x3d7
[ 106.124557] blk_finish_plug+0x37/0x4f
[ 106.125019] read_pages+0x3ef/0x430
[ 106.125446] __do_page_cache_readahead+0x18e/0x2fc
[ 106.126027] force_page_cache_readahead+0x121/0x133
[ 106.126621] page_cache_sync_readahead+0x35f/0x3bb
[ 106.127229] generic_file_buffered_read+0x410/0x1860
[ 106.127932] __vfs_read+0x319/0x38f
[ 106.128415] vfs_read+0xd2/0x19a
[ 106.128817] ksys_read+0xb9/0x135
[ 106.129225] do_syscall_64+0x140/0x385
[ 106.129684] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 106.130292]
[ 106.130292] other info that might help us debug this:
[ 106.130292]
[ 106.131226] Chain exists of:
[ 106.131226] &sbq->ws[i].wait -->
&(&hctx->dispatch_wait_lock)->rlock -->
&(&sb->map[i].swap_lock)->rlock
[ 106.131226]
[ 106.132865] Possible interrupt unsafe locking scenario:
[ 106.132865]
[ 106.133659] CPU0 CPU1
[ 106.134194] ---- ----
[ 106.134733] lock(&(&sb->map[i].swap_lock)->rlock);
[ 106.135318] local_irq_disable();
[ 106.136014] lock(&sbq->ws[i].wait);
[ 106.136747]
lock(&(&hctx->dispatch_wait_lock)->rlock);
[ 106.137742] <Interrupt>
[ 106.138110] lock(&sbq->ws[i].wait);
[ 106.138625]
[ 106.138625] *** DEADLOCK ***
[ 106.138625]
[ 106.139430] 3 locks held by fio/1043:
[ 106.139947] #0:
0000000076ff0fd9 (rcu_read_lock){....}, at:
hctx_lock+0x29/0xe8
[ 106.140813] #1:
000000002feb1016 (&sbq->ws[i].wait){..-.}, at:
blk_mq_dispatch_rq_list+0x4ad/0xd7c
[ 106.141877] #2:
000000007eec8b2f
(&(&hctx->dispatch_wait_lock)->rlock){....}, at:
blk_mq_dispatch_rq_list+0x4c1/0xd7c
[ 106.143267]
[ 106.143267] the dependencies between SOFTIRQ-irq-safe lock and the
holding lock:
[ 106.144351] -> (&sbq->ws[i].wait){..-.} ops: 82 {
[ 106.144926] IN-SOFTIRQ-W at:
[ 106.145314] _raw_spin_lock_irqsave+0x4b/0x82
[ 106.146042] __wake_up_common_lock+0x119/0x1b9
[ 106.146785] sbitmap_queue_wake_up+0x33f/0x383
[ 106.147567] sbitmap_queue_clear+0x4c/0x9a
[ 106.148379] __blk_mq_free_request+0x188/0x1d3
[ 106.149148] blk_mq_free_request+0x23b/0x26b
[ 106.149864] scsi_end_request+0x345/0x5d7
[ 106.150546] scsi_io_completion+0x4b5/0x8f0
[ 106.151367] scsi_finish_command+0x412/0x456
[ 106.152157] scsi_softirq_done+0x23f/0x29b
[ 106.152855] blk_done_softirq+0x2a7/0x2e6
[ 106.153537] __do_softirq+0x360/0x6ad
[ 106.154280] run_ksoftirqd+0x2f/0x5b
[ 106.155020] smpboot_thread_fn+0x3a5/0x3db
[ 106.155828] kthread+0x1d4/0x1e4
[ 106.156526] ret_from_fork+0x3a/0x50
[ 106.157267] INITIAL USE at:
[ 106.157713] _raw_spin_lock_irqsave+0x4b/0x82
[ 106.158542] prepare_to_wait_exclusive+0xa8/0x215
[ 106.159421] blk_mq_get_tag+0x34f/0x6e4
[ 106.160186] blk_mq_get_request+0x48e/0xaef
[ 106.160997] blk_mq_make_request+0x27e/0xbd2
[ 106.161828] generic_make_request+0x4d1/0x873
[ 106.162661] submit_bio+0x20c/0x253
[ 106.163379] mpage_bio_submit+0x44/0x4b
[ 106.164142] mpage_readpages+0x3c2/0x407
[ 106.164919] read_pages+0x13a/0x430
[ 106.165633] __do_page_cache_readahead+0x18e/0x2fc
[ 106.166530] force_page_cache_readahead+0x121/0x133
[ 106.167439] page_cache_sync_readahead+0x35f/0x3bb
[ 106.168337] generic_file_buffered_read+0x410/0x1860
[ 106.169255] __vfs_read+0x319/0x38f
[ 106.169977] vfs_read+0xd2/0x19a
[ 106.170662] ksys_read+0xb9/0x135
[ 106.171356] do_syscall_64+0x140/0x385
[ 106.172120] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 106.173051] }
[ 106.173308] ... key at: [<
ffffffff85094600>] __key.26481+0x0/0x40
[ 106.174219] ... acquired at:
[ 106.174646] _raw_spin_lock+0x33/0x64
[ 106.175183] blk_mq_dispatch_rq_list+0x4c1/0xd7c
[ 106.175843] blk_mq_do_dispatch_sched+0x23a/0x287
[ 106.176518] blk_mq_sched_dispatch_requests+0x379/0x3fc
[ 106.177262] __blk_mq_run_hw_queue+0x137/0x17e
[ 106.177900] __blk_mq_delay_run_hw_queue+0x80/0x25f
[ 106.178591] blk_mq_run_hw_queue+0x151/0x187
[ 106.179207] blk_mq_sched_insert_requests+0x13f/0x175
[ 106.179926] blk_mq_flush_plug_list+0x7d6/0x81b
[ 106.180571] blk_flush_plug_list+0x392/0x3d7
[ 106.181187] blk_finish_plug+0x37/0x4f
[ 106.181737] __se_sys_io_submit+0x171/0x304
[ 106.182346] do_syscall_64+0x140/0x385
[ 106.182895] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 106.183607]
[ 106.183830] -> (&(&hctx->dispatch_wait_lock)->rlock){....} ops: 1 {
[ 106.184691] INITIAL USE at:
[ 106.185119] _raw_spin_lock+0x33/0x64
[ 106.185838] blk_mq_dispatch_rq_list+0x4c1/0xd7c
[ 106.186697] blk_mq_do_dispatch_sched+0x23a/0x287
[ 106.187551] blk_mq_sched_dispatch_requests+0x379/0x3fc
[ 106.188481] __blk_mq_run_hw_queue+0x137/0x17e
[ 106.189307] __blk_mq_delay_run_hw_queue+0x80/0x25f
[ 106.190189] blk_mq_run_hw_queue+0x151/0x187
[ 106.190989] blk_mq_sched_insert_requests+0x13f/0x175
[ 106.191902] blk_mq_flush_plug_list+0x7d6/0x81b
[ 106.192739] blk_flush_plug_list+0x392/0x3d7
[ 106.193535] blk_finish_plug+0x37/0x4f
[ 106.194269] __se_sys_io_submit+0x171/0x304
[ 106.195059] do_syscall_64+0x140/0x385
[ 106.195794] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 106.196705] }
[ 106.196950] ... key at: [<
ffffffff84880620>] __key.51231+0x0/0x40
[ 106.197853] ... acquired at:
[ 106.198270] lock_acquire+0x280/0x2f3
[ 106.198806] _raw_spin_lock+0x33/0x64
[ 106.199337] sbitmap_get+0xd5/0x22c
[ 106.199850] __sbitmap_queue_get+0xe8/0x177
[ 106.200450] __blk_mq_get_tag+0x1e6/0x22d
[ 106.201035] blk_mq_get_tag+0x1db/0x6e4
[ 106.201589] blk_mq_get_driver_tag+0x161/0x258
[ 106.202237] blk_mq_dispatch_rq_list+0x5b9/0xd7c
[ 106.202902] blk_mq_do_dispatch_sched+0x23a/0x287
[ 106.203572] blk_mq_sched_dispatch_requests+0x379/0x3fc
[ 106.204316] __blk_mq_run_hw_queue+0x137/0x17e
[ 106.204956] __blk_mq_delay_run_hw_queue+0x80/0x25f
[ 106.205649] blk_mq_run_hw_queue+0x151/0x187
[ 106.206269] blk_mq_sched_insert_requests+0x13f/0x175
[ 106.206997] blk_mq_flush_plug_list+0x7d6/0x81b
[ 106.207644] blk_flush_plug_list+0x392/0x3d7
[ 106.208264] blk_finish_plug+0x37/0x4f
[ 106.208814] __se_sys_io_submit+0x171/0x304
[ 106.209415] do_syscall_64+0x140/0x385
[ 106.209965] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 106.210684]
[ 106.210904]
[ 106.210904] the dependencies between the lock to be acquired
[ 106.210905] and SOFTIRQ-irq-unsafe lock:
[ 106.212541] -> (&(&sb->map[i].swap_lock)->rlock){+.+.} ops: 1969 {
[ 106.213393] HARDIRQ-ON-W at:
[ 106.213840] _raw_spin_lock+0x33/0x64
[ 106.214570] sbitmap_get+0xd5/0x22c
[ 106.215282] __sbitmap_queue_get+0xe8/0x177
[ 106.216086] __blk_mq_get_tag+0x1e6/0x22d
[ 106.216876] blk_mq_get_tag+0x1db/0x6e4
[ 106.217627] blk_mq_get_driver_tag+0x161/0x258
[ 106.218465] blk_mq_dispatch_rq_list+0x28e/0xd7c
[ 106.219326] blk_mq_do_dispatch_sched+0x23a/0x287
[ 106.220198] blk_mq_sched_dispatch_requests+0x379/0x3fc
[ 106.221138] __blk_mq_run_hw_queue+0x137/0x17e
[ 106.221975] __blk_mq_delay_run_hw_queue+0x80/0x25f
[ 106.222874] blk_mq_run_hw_queue+0x151/0x187
[ 106.223686] blk_mq_sched_insert_requests+0x13f/0x175
[ 106.224597] blk_mq_flush_plug_list+0x7d6/0x81b
[ 106.225444] blk_flush_plug_list+0x392/0x3d7
[ 106.226255] blk_finish_plug+0x37/0x4f
[ 106.227006] read_pages+0x3ef/0x430
[ 106.227717] __do_page_cache_readahead+0x18e/0x2fc
[ 106.228595] force_page_cache_readahead+0x121/0x133
[ 106.229491] page_cache_sync_readahead+0x35f/0x3bb
[ 106.230373] generic_file_buffered_read+0x410/0x1860
[ 106.231277] __vfs_read+0x319/0x38f
[ 106.231986] vfs_read+0xd2/0x19a
[ 106.232666] ksys_read+0xb9/0x135
[ 106.233350] do_syscall_64+0x140/0x385
[ 106.234097] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 106.235012] SOFTIRQ-ON-W at:
[ 106.235460] _raw_spin_lock+0x33/0x64
[ 106.236195] sbitmap_get+0xd5/0x22c
[ 106.236913] __sbitmap_queue_get+0xe8/0x177
[ 106.237715] __blk_mq_get_tag+0x1e6/0x22d
[ 106.238488] blk_mq_get_tag+0x1db/0x6e4
[ 106.239244] blk_mq_get_driver_tag+0x161/0x258
[ 106.240079] blk_mq_dispatch_rq_list+0x28e/0xd7c
[ 106.240937] blk_mq_do_dispatch_sched+0x23a/0x287
[ 106.241806] blk_mq_sched_dispatch_requests+0x379/0x3fc
[ 106.242751] __blk_mq_run_hw_queue+0x137/0x17e
[ 106.243579] __blk_mq_delay_run_hw_queue+0x80/0x25f
[ 106.244469] blk_mq_run_hw_queue+0x151/0x187
[ 106.245277] blk_mq_sched_insert_requests+0x13f/0x175
[ 106.246191] blk_mq_flush_plug_list+0x7d6/0x81b
[ 106.247044] blk_flush_plug_list+0x392/0x3d7
[ 106.247859] blk_finish_plug+0x37/0x4f
[ 106.248749] read_pages+0x3ef/0x430
[ 106.249463] __do_page_cache_readahead+0x18e/0x2fc
[ 106.250357] force_page_cache_readahead+0x121/0x133
[ 106.251263] page_cache_sync_readahead+0x35f/0x3bb
[ 106.252157] generic_file_buffered_read+0x410/0x1860
[ 106.253084] __vfs_read+0x319/0x38f
[ 106.253808] vfs_read+0xd2/0x19a
[ 106.254488] ksys_read+0xb9/0x135
[ 106.255186] do_syscall_64+0x140/0x385
[ 106.255943] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 106.256867] INITIAL USE at:
[ 106.257300] _raw_spin_lock+0x33/0x64
[ 106.258033] sbitmap_get+0xd5/0x22c
[ 106.258747] __sbitmap_queue_get+0xe8/0x177
[ 106.259542] __blk_mq_get_tag+0x1e6/0x22d
[ 106.260320] blk_mq_get_tag+0x1db/0x6e4
[ 106.261072] blk_mq_get_driver_tag+0x161/0x258
[ 106.261902] blk_mq_dispatch_rq_list+0x28e/0xd7c
[ 106.262762] blk_mq_do_dispatch_sched+0x23a/0x287
[ 106.263626] blk_mq_sched_dispatch_requests+0x379/0x3fc
[ 106.264571] __blk_mq_run_hw_queue+0x137/0x17e
[ 106.265409] __blk_mq_delay_run_hw_queue+0x80/0x25f
[ 106.266302] blk_mq_run_hw_queue+0x151/0x187
[ 106.267111] blk_mq_sched_insert_requests+0x13f/0x175
[ 106.268028] blk_mq_flush_plug_list+0x7d6/0x81b
[ 106.268878] blk_flush_plug_list+0x392/0x3d7
[ 106.269694] blk_finish_plug+0x37/0x4f
[ 106.270432] read_pages+0x3ef/0x430
[ 106.271139] __do_page_cache_readahead+0x18e/0x2fc
[ 106.272040] force_page_cache_readahead+0x121/0x133
[ 106.272932] page_cache_sync_readahead+0x35f/0x3bb
[ 106.273811] generic_file_buffered_read+0x410/0x1860
[ 106.274709] __vfs_read+0x319/0x38f
[ 106.275407] vfs_read+0xd2/0x19a
[ 106.276074] ksys_read+0xb9/0x135
[ 106.276764] do_syscall_64+0x140/0x385
[ 106.277500] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 106.278417] }
[ 106.278676] ... key at: [<
ffffffff85094640>] __key.26212+0x0/0x40
[ 106.279586] ... acquired at:
[ 106.280026] lock_acquire+0x280/0x2f3
[ 106.280559] _raw_spin_lock+0x33/0x64
[ 106.281101] sbitmap_get+0xd5/0x22c
[ 106.281610] __sbitmap_queue_get+0xe8/0x177
[ 106.282221] __blk_mq_get_tag+0x1e6/0x22d
[ 106.282809] blk_mq_get_tag+0x1db/0x6e4
[ 106.283368] blk_mq_get_driver_tag+0x161/0x258
[ 106.284018] blk_mq_dispatch_rq_list+0x5b9/0xd7c
[ 106.284685] blk_mq_do_dispatch_sched+0x23a/0x287
[ 106.285371] blk_mq_sched_dispatch_requests+0x379/0x3fc
[ 106.286135] __blk_mq_run_hw_queue+0x137/0x17e
[ 106.286806] __blk_mq_delay_run_hw_queue+0x80/0x25f
[ 106.287515] blk_mq_run_hw_queue+0x151/0x187
[ 106.288149] blk_mq_sched_insert_requests+0x13f/0x175
[ 106.289041] blk_mq_flush_plug_list+0x7d6/0x81b
[ 106.289912] blk_flush_plug_list+0x392/0x3d7
[ 106.290590] blk_finish_plug+0x37/0x4f
[ 106.291238] __se_sys_io_submit+0x171/0x304
[ 106.291864] do_syscall_64+0x140/0x385
[ 106.292534] entry_SYSCALL_64_after_hwframe+0x49/0xbe
Reported-by: Ming Lei <ming.lei@redhat.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
projects / users / willy / linux.git / log