====================================================== WARNING: possible circular locking dependency detected 6.1.16-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.0/4462 is trying to acquire lock: ffff0000cc4e60a8 ((&sq->pending_timer)){+.-.}-{0:0}, at: del_timer_sync+0x74/0x210 kernel/time/timer.c:1417 but task is already holding lock: ffff800019965b30 (&blkcg->lock){....}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff800019965b30 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy+0x1b8/0x4bc block/blk-cgroup.c:1495 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+0x54/0x6c kernel/locking/spinlock.c:154 spin_lock include/linux/spinlock.h:350 [inline] blkg_create+0x9f4/0x1158 block/blk-cgroup.c:336 blkcg_init_disk+0xe4/0x32c block/blk-cgroup.c:1260 __alloc_disk_node+0x26c/0x484 block/genhd.c:1385 __blk_alloc_disk+0x40/0xbc block/genhd.c:1424 brd_alloc+0x2ac/0x5c8 drivers/block/brd.c:397 brd_init+0x108/0x1c4 drivers/block/brd.c:484 do_one_initcall+0x310/0xda4 init/main.c:1303 do_initcall_level+0x154/0x214 init/main.c:1376 do_initcalls+0x58/0xac init/main.c:1392 do_basic_setup+0x8c/0xa0 init/main.c:1411 kernel_init_freeable+0x3a4/0x528 init/main.c:1631 kernel_init+0x24/0x29c init/main.c:1519 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 -> #1 (&q->queue_lock){..-.}-{2:2}: __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline] _raw_spin_lock_irq+0x70/0x9c kernel/locking/spinlock.c:170 spin_lock_irq include/linux/spinlock.h:375 [inline] throtl_pending_timer_fn+0x104/0xdcc block/blk-throttle.c:1193 call_timer_fn+0x270/0xcf4 kernel/time/timer.c:1474 expire_timers kernel/time/timer.c:1519 [inline] __run_timers+0x554/0x718 kernel/time/timer.c:1790 run_timer_softirq+0x7c/0x114 kernel/time/timer.c:1803 __do_softirq+0x37c/0xff4 kernel/softirq.c:571 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:79 call_on_irq_stack+0x2c/0x54 arch/arm64/kernel/entry.S:889 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:84 invoke_softirq kernel/softirq.c:452 [inline] __irq_exit_rcu+0x28c/0x534 kernel/softirq.c:650 irq_exit_rcu+0x14/0x84 kernel/softirq.c:662 __el1_irq arch/arm64/kernel/entry-common.c:472 [inline] el1_interrupt+0x38/0x68 arch/arm64/kernel/entry-common.c:486 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:577 arch_local_irq_restore arch/arm64/include/asm/irqflags.h:122 [inline] console_emit_next_record+0x94c/0xb40 kernel/printk/printk.c:2737 console_unlock+0x294/0x6f8 kernel/printk/printk.c:2860 vprintk_emit+0x14c/0x2e4 kernel/printk/printk.c:2268 vprintk_default+0xa0/0xe4 kernel/printk/printk.c:2279 vprintk+0x218/0x2f0 kernel/printk/printk_safe.c:50 _printk+0xdc/0x128 kernel/printk/printk.c:2289 addrconf_notify+0xa40/0xc94 net/ipv6/addrconf.c:3636 notifier_call_chain kernel/notifier.c:87 [inline] raw_notifier_call_chain+0xd4/0x164 kernel/notifier.c:455 call_netdevice_notifiers_info net/core/dev.c:1945 [inline] netdev_state_change+0x180/0x22c net/core/dev.c:1334 linkwatch_do_dev+0x2a4/0x3a4 net/core/link_watch.c:168 __linkwatch_run_queue+0x3a0/0x700 net/core/link_watch.c:221 linkwatch_event+0x58/0x68 net/core/link_watch.c:264 process_one_work+0x868/0x16f4 kernel/workqueue.c:2289 worker_thread+0x8e4/0xfec kernel/workqueue.c:2436 kthread+0x24c/0x2d4 kernel/kthread.c:376 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 -> #0 ((&sq->pending_timer)){+.-.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3098 [inline] check_prevs_add kernel/locking/lockdep.c:3217 [inline] validate_chain kernel/locking/lockdep.c:3832 [inline] __lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056 lock_acquire+0x300/0x8e4 kernel/locking/lockdep.c:5669 del_timer_sync+0x9c/0x210 kernel/time/timer.c:1417 throtl_pd_free+0x20/0x48 block/blk-throttle.c:493 blkcg_deactivate_policy+0x2d8/0x4bc block/blk-cgroup.c:1499 blk_throtl_exit+0x9c/0x13c block/blk-throttle.c:2406 blkcg_exit_disk+0x4c/0x5c block/blk-cgroup.c:1301 disk_release+0x170/0x2d8 block/genhd.c:1171 device_release+0x8c/0x1ac kobject_cleanup lib/kobject.c:681 [inline] kobject_release lib/kobject.c:712 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x2a8/0x41c lib/kobject.c:729 put_device+0x28/0x40 drivers/base/core.c:3772 put_disk+0x4c/0x64 block/genhd.c:1450 loop_remove drivers/block/loop.c:2080 [inline] loop_control_remove drivers/block/loop.c:2128 [inline] loop_control_ioctl+0x534/0x650 drivers/block/loop.c:2166 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581 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 *** 3 locks held by syz-executor.0/4462: #0: ffff0000cc4f0b28 (&q->blkcg_mutex){+.+.}-{3:3}, at: blkcg_deactivate_policy+0xfc/0x4bc block/blk-cgroup.c:1487 #1: ffff0000cc4f0918 (&q->queue_lock){..-.}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:375 [inline] #1: ffff0000cc4f0918 (&q->queue_lock){..-.}-{2:2}, at: blkcg_deactivate_policy+0x108/0x4bc block/blk-cgroup.c:1488 #2: ffff800019965b30 (&blkcg->lock){....}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] #2: ffff800019965b30 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy+0x1b8/0x4bc block/blk-cgroup.c:1495 stack backtrace: CPU: 0 PID: 4462 Comm: syz-executor.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_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165 __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 print_circular_bug+0x150/0x1b8 kernel/locking/lockdep.c:2056 check_noncircular+0x2cc/0x378 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 kernel/locking/lockdep.c:3832 [inline] __lock_acquire+0x3338/0x764c kernel/locking/lockdep.c:5056 lock_acquire+0x300/0x8e4 kernel/locking/lockdep.c:5669 del_timer_sync+0x9c/0x210 kernel/time/timer.c:1417 throtl_pd_free+0x20/0x48 block/blk-throttle.c:493 blkcg_deactivate_policy+0x2d8/0x4bc block/blk-cgroup.c:1499 blk_throtl_exit+0x9c/0x13c block/blk-throttle.c:2406 blkcg_exit_disk+0x4c/0x5c block/blk-cgroup.c:1301 disk_release+0x170/0x2d8 block/genhd.c:1171 device_release+0x8c/0x1ac kobject_cleanup lib/kobject.c:681 [inline] kobject_release lib/kobject.c:712 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x2a8/0x41c lib/kobject.c:729 put_device+0x28/0x40 drivers/base/core.c:3772 put_disk+0x4c/0x64 block/genhd.c:1450 loop_remove drivers/block/loop.c:2080 [inline] loop_control_remove drivers/block/loop.c:2128 [inline] loop_control_ioctl+0x534/0x650 drivers/block/loop.c:2166 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581