====================================================== WARNING: possible circular locking dependency detected 6.1.16-syzkaller #0 Not tainted ------------------------------------------------------ ksoftirqd/0/15 is trying to acquire lock: ffff88801eb87530 (&q->queue_lock){..-.}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:375 [inline] ffff88801eb87530 (&q->queue_lock){..-.}-{2:2}, at: throtl_pending_timer_fn+0x10d/0x1be0 block/blk-throttle.c:1193 but task is already holding lock: ffffc90000147a60 ((&sq->pending_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:41 [inline] ffffc90000147a60 ((&sq->pending_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbd/0x840 kernel/time/timer.c:1464 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 ((&sq->pending_timer)){+.-.}-{0:0}: lock_acquire+0x23a/0x630 kernel/locking/lockdep.c:5669 del_timer_sync+0x111/0x2e0 kernel/time/timer.c:1417 throtl_pd_free+0x15/0x40 block/blk-throttle.c:493 blkcg_deactivate_policy+0x32d/0x550 block/blk-cgroup.c:1499 blk_throtl_exit+0xa6/0x140 block/blk-throttle.c:2406 disk_release+0x1dd/0x380 block/genhd.c:1171 device_release+0x91/0x1c0 kobject_cleanup lib/kobject.c:681 [inline] kobject_release lib/kobject.c:712 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x224/0x460 lib/kobject.c:729 do_floppy_init+0x373/0xc59 drivers/block/floppy.c:4758 async_run_entry_fn+0xa2/0x410 kernel/async.c:127 process_one_work+0x909/0x1380 kernel/workqueue.c:2289 worker_thread+0xa5f/0x1210 kernel/workqueue.c:2436 kthread+0x268/0x300 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 -> #1 (&blkcg->lock){....}-{2:2}: lock_acquire+0x23a/0x630 kernel/locking/lockdep.c:5669 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline] _raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:350 [inline] blkg_create+0xa94/0x1280 block/blk-cgroup.c:336 blkcg_init_disk+0xee/0x350 block/blk-cgroup.c:1260 __alloc_disk_node+0x2ce/0x590 block/genhd.c:1385 __blk_alloc_disk+0x2c/0x80 block/genhd.c:1424 brd_alloc+0x2f9/0x6a0 drivers/block/brd.c:397 brd_init+0x100/0x1c2 drivers/block/brd.c:484 do_one_initcall+0x2d6/0xa80 init/main.c:1303 do_initcall_level+0x157/0x207 init/main.c:1376 do_initcalls+0x49/0x86 init/main.c:1392 kernel_init_freeable+0x473/0x61f init/main.c:1631 kernel_init+0x19/0x290 init/main.c:1519 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 -> #0 (&q->queue_lock){..-.}-{2:2}: check_prev_add kernel/locking/lockdep.c:3098 [inline] check_prevs_add kernel/locking/lockdep.c:3217 [inline] validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056 lock_acquire+0x23a/0x630 kernel/locking/lockdep.c:5669 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline] _raw_spin_lock_irq+0xcf/0x110 kernel/locking/spinlock.c:170 spin_lock_irq include/linux/spinlock.h:375 [inline] throtl_pending_timer_fn+0x10d/0x1be0 block/blk-throttle.c:1193 call_timer_fn+0x200/0x840 kernel/time/timer.c:1474 expire_timers kernel/time/timer.c:1519 [inline] __run_timers+0x67c/0x890 kernel/time/timer.c:1790 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1803 __do_softirq+0x30d/0xb1b kernel/softirq.c:571 run_ksoftirqd+0xc1/0x120 kernel/softirq.c:934 smpboot_thread_fn+0x51b/0xa10 kernel/smpboot.c:164 kthread+0x268/0x300 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 other info that might help us debug this: Chain exists of: &q->queue_lock --> &blkcg->lock --> (&sq->pending_timer) Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock((&sq->pending_timer)); lock(&blkcg->lock); lock((&sq->pending_timer)); lock(&q->queue_lock); *** DEADLOCK *** 1 lock held by ksoftirqd/0/15: #0: ffffc90000147a60 ((&sq->pending_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:41 [inline] #0: ffffc90000147a60 ((&sq->pending_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbd/0x840 kernel/time/timer.c:1464 stack backtrace: CPU: 0 PID: 15 Comm: ksoftirqd/0 Not tainted 6.1.16-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106 check_noncircular+0x2fa/0x3b0 kernel/locking/lockdep.c:2178 check_prev_add kernel/locking/lockdep.c:3098 [inline] check_prevs_add kernel/locking/lockdep.c:3217 [inline] validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056 lock_acquire+0x23a/0x630 kernel/locking/lockdep.c:5669 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline] _raw_spin_lock_irq+0xcf/0x110 kernel/locking/spinlock.c:170 spin_lock_irq include/linux/spinlock.h:375 [inline] throtl_pending_timer_fn+0x10d/0x1be0 block/blk-throttle.c:1193 call_timer_fn+0x200/0x840 kernel/time/timer.c:1474 expire_timers kernel/time/timer.c:1519 [inline] __run_timers+0x67c/0x890 kernel/time/timer.c:1790 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1803 __do_softirq+0x30d/0xb1b kernel/softirq.c:571 run_ksoftirqd+0xc1/0x120 kernel/softirq.c:934 smpboot_thread_fn+0x51b/0xa10 kernel/smpboot.c:164 kthread+0x268/0x300 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306