====================================================== WARNING: possible circular locking dependency detected 6.1.16-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.1/26614 is trying to acquire lock: ffff0001064ab0a8 ((&sq->pending_timer)){+.-.}-{0:0}, at: del_timer_sync+0x74/0x210 kernel/time/timer.c:1417 but task is already holding lock: ffff0000ce422130 (&blkcg->lock){....}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffff0000ce422130 (&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] lock_acquire+0x340/0x8e4 kernel/locking/lockdep.c:5672 fs_reclaim_acquire+0xbc/0x12c mm/page_alloc.c:4699 might_alloc include/linux/sched/mm.h:271 [inline] slab_pre_alloc_hook mm/slab.h:710 [inline] slab_alloc_node mm/slub.c:3318 [inline] slab_alloc mm/slub.c:3406 [inline] __kmem_cache_alloc_lru mm/slub.c:3413 [inline] kmem_cache_alloc+0x64/0x37c mm/slub.c:3422 kmem_cache_zalloc include/linux/slab.h:679 [inline] __kernfs_new_node+0xe4/0x66c fs/kernfs/dir.c:608 kernfs_new_node+0x98/0x184 fs/kernfs/dir.c:670 __kernfs_create_file+0x60/0x2d4 fs/kernfs/file.c:1043 sysfs_add_file_mode_ns+0x1dc/0x298 fs/sysfs/file.c:294 create_files fs/sysfs/group.c:64 [inline] internal_create_group+0x428/0xbec fs/sysfs/group.c:148 internal_create_groups fs/sysfs/group.c:188 [inline] sysfs_create_groups+0x60/0x130 fs/sysfs/group.c:214 device_add_groups drivers/base/core.c:2719 [inline] device_add_attrs+0xd8/0x750 drivers/base/core.c:2867 device_add+0x5e8/0xef4 drivers/base/core.c:3615 netdev_register_kobject+0x15c/0x2d8 net/core/net-sysfs.c:2015 register_netdevice+0xcb8/0x125c net/core/dev.c:10057 __ip_tunnel_create+0x23c/0x304 net/ipv4/ip_tunnel.c:267 ip_tunnel_init_net+0x1e0/0x5b0 net/ipv4/ip_tunnel.c:1073 ipip_init_net+0x38/0x48 net/ipv4/ipip.c:591 ops_init+0x2e8/0x548 net/core/net_namespace.c:135 setup_net+0x424/0xaac net/core/net_namespace.c:332 copy_net_ns+0x2f4/0x590 net/core/net_namespace.c:478 create_new_namespaces+0x344/0x614 kernel/nsproxy.c:110 copy_namespaces+0x354/0x3bc kernel/nsproxy.c:178 copy_process+0x186c/0x38d0 kernel/fork.c:2259 kernel_clone+0x1d8/0xb28 kernel/fork.c:2676 __do_sys_clone kernel/fork.c:2817 [inline] __se_sys_clone kernel/fork.c:2785 [inline] __arm64_sys_clone+0x1e0/0x234 kernel/fork.c:2785 __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 -> #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.1/26614: #0: ffff0000cc3876d0 (&q->blkcg_mutex){+.+.}-{3:3}, at: blkcg_deactivate_policy+0xfc/0x4bc block/blk-cgroup.c:1487 #1: ffff0000cc3874c0 (&q->queue_lock){..-.}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:375 [inline] #1: ffff0000cc3874c0 (&q->queue_lock){..-.}-{2:2}, at: blkcg_deactivate_policy+0x108/0x4bc block/blk-cgroup.c:1488 #2: ffff0000ce422130 (&blkcg->lock){....}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] #2: ffff0000ce422130 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy+0x1b8/0x4bc block/blk-cgroup.c:1495 stack backtrace: CPU: 1 PID: 26614 Comm: syz-executor.1 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