====================================================== WARNING: possible circular locking dependency detected 5.19.0-rc4-next-20220628-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor230/5049 is trying to acquire lock: ffff88807cd240a8 ((&sq->pending_timer)){+.-.}-{0:0}, at: del_timer_sync+0x33/0x1b0 kernel/time/timer.c:1416 but task is already holding lock: ffffffff91101b70 (&blkcg->lock){....}-{2:2}, at: spin_lock include/linux/spinlock.h:360 [inline] ffffffff91101b70 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy block/blk-cgroup.c:1516 [inline] ffffffff91101b70 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy+0x1e7/0x4e0 block/blk-cgroup.c:1498 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&blkcg->lock){....}-{2:2}: __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:360 [inline] blkg_create+0x45e/0x1000 block/blk-cgroup.c:344 blkcg_init_queue+0xb2/0x620 block/blk-cgroup.c:1282 __alloc_disk_node+0x260/0x610 block/genhd.c:1365 __blk_alloc_disk+0x35/0x70 block/genhd.c:1405 brd_alloc.part.0+0x27f/0x7a0 drivers/block/brd.c:391 brd_alloc drivers/block/brd.c:374 [inline] brd_init+0x1b8/0x24b drivers/block/brd.c:477 do_one_initcall+0xfe/0x650 init/main.c:1300 do_initcall_level init/main.c:1375 [inline] do_initcalls init/main.c:1391 [inline] do_basic_setup init/main.c:1410 [inline] kernel_init_freeable+0x6b1/0x73a init/main.c:1617 kernel_init+0x1a/0x1d0 init/main.c:1506 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302 -> #1 (&q->queue_lock){..-.}-{2:2}: __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline] _raw_spin_lock_irq+0x32/0x50 kernel/locking/spinlock.c:170 spin_lock_irq include/linux/spinlock.h:385 [inline] throtl_pending_timer_fn+0xf7/0x1690 block/blk-throttle.c:1152 call_timer_fn+0x1a0/0x6b0 kernel/time/timer.c:1474 expire_timers kernel/time/timer.c:1519 [inline] __run_timers.part.0+0x674/0xa80 kernel/time/timer.c:1790 __run_timers kernel/time/timer.c:1768 [inline] run_timer_softirq+0xb3/0x1d0 kernel/time/timer.c:1803 __do_softirq+0x29b/0x9c2 kernel/softirq.c:571 invoke_softirq kernel/softirq.c:445 [inline] __irq_exit_rcu+0x123/0x180 kernel/softirq.c:650 irq_exit_rcu+0x5/0x20 kernel/softirq.c:662 sysvec_apic_timer_interrupt+0x93/0xc0 arch/x86/kernel/apic/apic.c:1106 asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:649 partial_name_hash include/linux/stringhash.h:45 [inline] kernfs_name_hash+0x8b/0x120 fs/kernfs/dir.c:311 kernfs_add_one+0x246/0x550 fs/kernfs/dir.c:752 __kernfs_create_file+0x29c/0x350 fs/kernfs/file.c:1016 sysfs_add_file_mode_ns+0x20f/0x3f0 fs/sysfs/file.c:294 create_files fs/sysfs/group.c:64 [inline] internal_create_group+0x322/0xb10 fs/sysfs/group.c:148 internal_create_groups.part.0+0x90/0x140 fs/sysfs/group.c:188 internal_create_groups fs/sysfs/group.c:184 [inline] sysfs_create_groups+0x25/0x50 fs/sysfs/group.c:214 device_add_groups drivers/base/core.c:2560 [inline] device_add_attrs drivers/base/core.c:2714 [inline] device_add+0x7ee/0x1e90 drivers/base/core.c:3456 device_add_disk+0x37e/0xe20 block/genhd.c:466 add_disk include/linux/blkdev.h:768 [inline] loop_add+0x884/0xaf0 drivers/block/loop.c:2031 loop_control_ioctl+0x133/0x540 drivers/block/loop.c:2151 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 -> #0 ((&sq->pending_timer)){+.-.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3829 [inline] __lock_acquire+0x2abe/0x5660 kernel/locking/lockdep.c:5053 lock_acquire kernel/locking/lockdep.c:5665 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5630 del_timer_sync+0x5b/0x1b0 kernel/time/timer.c:1417 throtl_pd_free+0x15/0x40 block/blk-throttle.c:500 blkcg_deactivate_policy block/blk-cgroup.c:1520 [inline] blkcg_deactivate_policy+0x2d2/0x4e0 block/blk-cgroup.c:1498 blk_throtl_exit+0x8a/0x1a0 block/blk-throttle.c:2336 blkcg_init_queue+0x19b/0x620 block/blk-cgroup.c:1301 __alloc_disk_node+0x260/0x610 block/genhd.c:1365 __blk_mq_alloc_disk+0x133/0x1c0 block/blk-mq.c:3927 loop_add+0x3e2/0xaf0 drivers/block/loop.c:1978 loop_control_ioctl+0x133/0x540 drivers/block/loop.c:2151 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 other info that might help us debug this: Chain exists of: (&sq->pending_timer) --> &q->queue_lock --> &blkcg->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&blkcg->lock); lock(&q->queue_lock); lock(&blkcg->lock); lock((&sq->pending_timer)); *** DEADLOCK *** 2 locks held by syz-executor230/5049: #0: ffff88807f07e8e0 (&q->queue_lock){..-.}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:385 [inline] #0: ffff88807f07e8e0 (&q->queue_lock){..-.}-{2:2}, at: blkcg_deactivate_policy block/blk-cgroup.c:1509 [inline] #0: ffff88807f07e8e0 (&q->queue_lock){..-.}-{2:2}, at: blkcg_deactivate_policy+0xfe/0x4e0 block/blk-cgroup.c:1498 #1: ffffffff91101b70 (&blkcg->lock){....}-{2:2}, at: spin_lock include/linux/spinlock.h:360 [inline] #1: ffffffff91101b70 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy block/blk-cgroup.c:1516 [inline] #1: ffffffff91101b70 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy+0x1e7/0x4e0 block/blk-cgroup.c:1498 stack backtrace: CPU: 1 PID: 5049 Comm: syz-executor230 Not tainted 5.19.0-rc4-next-20220628-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3829 [inline] __lock_acquire+0x2abe/0x5660 kernel/locking/lockdep.c:5053 lock_acquire kernel/locking/lockdep.c:5665 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5630 del_timer_sync+0x5b/0x1b0 kernel/time/timer.c:1417 throtl_pd_free+0x15/0x40 block/blk-throttle.c:500 blkcg_deactivate_policy block/blk-cgroup.c:1520 [inline] blkcg_deactivate_policy+0x2d2/0x4e0 block/blk-cgroup.c:1498 blk_throtl_exit+0x8a/0x1a0 block/blk-throttle.c:2336 blkcg_init_queue+0x19b/0x620 block/blk-cgroup.c:1301 __alloc_disk_node+0x260/0x610 block/genhd.c:1365 __blk_mq_alloc_disk+0x133/0x1c0 block/blk-mq.c:3927 loop_add+0x3e2/0xaf0 drivers/block/loop.c:1978 loop_control_ioctl+0x133/0x540 drivers/block/loop.c:2151 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f5250151c29 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f52501032f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f52501da4c8 RCX: 00007f5250151c29 RDX: 0000000000000000 RSI: 0000000000004c80 RDI: 0000000000000003 RBP: 00007f52501da4c0 R08: 0000000000000002 R09: 0000000000003237 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f5250103300 R13: 0000000000000002 R14: 00007f5250103400 R15: 0000000000022000