====================================================== WARNING: possible circular locking dependency detected 6.1.0-rc4-syzkaller-00356-g8f2975c2bb4c #0 Not tainted ------------------------------------------------------ syz-executor.4/26822 is trying to acquire lock: ffff8880418c00a8 ((&sq->pending_timer)){+.-.}-{0:0}, at: del_timer_sync+0x33/0x1b0 kernel/time/timer.c:1416 but task is already holding lock: ffffffff9138cc70 (&blkcg->lock){....}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] ffffffff9138cc70 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy block/blk-cgroup.c:1467 [inline] ffffffff9138cc70 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy+0x181/0x470 block/blk-cgroup.c:1449 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:350 [inline] blkg_create+0x662/0x1260 block/blk-cgroup.c:319 blkcg_init_disk+0xe0/0x6a0 block/blk-cgroup.c:1238 __alloc_disk_node+0x29d/0x650 block/genhd.c:1380 __blk_alloc_disk+0x35/0x90 block/genhd.c:1419 brd_alloc.part.0+0x281/0x760 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+0x13d/0x780 init/main.c:1303 do_initcall_level init/main.c:1376 [inline] do_initcalls init/main.c:1392 [inline] do_basic_setup init/main.c:1411 [inline] kernel_init_freeable+0x6ff/0x788 init/main.c:1631 kernel_init+0x1a/0x1d0 init/main.c:1519 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 -> #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:375 [inline] throtl_pending_timer_fn+0xf9/0x1ad0 block/blk-throttle.c:1193 call_timer_fn+0x1da/0x7c0 kernel/time/timer.c:1474 expire_timers kernel/time/timer.c:1519 [inline] __run_timers.part.0+0x6a2/0xaf0 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+0x1f7/0xad8 kernel/softirq.c:571 do_softirq.part.0+0xde/0x130 kernel/softirq.c:472 do_softirq kernel/softirq.c:464 [inline] __local_bh_enable_ip+0x102/0x120 kernel/softirq.c:396 spin_unlock_bh include/linux/spinlock.h:395 [inline] batadv_nc_purge_paths+0x2a5/0x3a0 net/batman-adv/network-coding.c:471 batadv_nc_worker+0x8f9/0xfa0 net/batman-adv/network-coding.c:720 process_one_work+0x9bf/0x1710 kernel/workqueue.c:2289 worker_thread+0x665/0x1080 kernel/workqueue.c:2436 kthread+0x2e4/0x3a0 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 -> #0 ((&sq->pending_timer)){+.-.}-{0:0}: check_prev_add kernel/locking/lockdep.c:3097 [inline] check_prevs_add kernel/locking/lockdep.c:3216 [inline] validate_chain kernel/locking/lockdep.c:3831 [inline] __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055 lock_acquire kernel/locking/lockdep.c:5668 [inline] lock_acquire+0x1df/0x630 kernel/locking/lockdep.c:5633 del_timer_sync+0x5b/0x1b0 kernel/time/timer.c:1417 throtl_pd_free+0x15/0x40 block/blk-throttle.c:493 blkcg_deactivate_policy block/blk-cgroup.c:1471 [inline] blkcg_deactivate_policy+0x26c/0x470 block/blk-cgroup.c:1449 blk_throtl_exit+0xb3/0x1e0 block/blk-throttle.c:2406 blkcg_init_disk+0x1ee/0x6a0 block/blk-cgroup.c:1262 __alloc_disk_node+0x29d/0x650 block/genhd.c:1380 __blk_mq_alloc_disk+0x13b/0x1f0 block/blk-mq.c:4035 loop_add+0x3e2/0xaf0 drivers/block/loop.c:1983 loop_control_ioctl+0x133/0x620 drivers/block/loop.c:2155 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+0x63/0xcd 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-executor.4/26822: #0: ffff8880205f00d0 (&q->queue_lock){..-.}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:375 [inline] #0: ffff8880205f00d0 (&q->queue_lock){..-.}-{2:2}, at: blkcg_deactivate_policy block/blk-cgroup.c:1460 [inline] #0: ffff8880205f00d0 (&q->queue_lock){..-.}-{2:2}, at: blkcg_deactivate_policy+0x9b/0x470 block/blk-cgroup.c:1449 #1: ffffffff9138cc70 (&blkcg->lock){....}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] #1: ffffffff9138cc70 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy block/blk-cgroup.c:1467 [inline] #1: ffffffff9138cc70 (&blkcg->lock){....}-{2:2}, at: blkcg_deactivate_policy+0x181/0x470 block/blk-cgroup.c:1449 stack backtrace: CPU: 1 PID: 26822 Comm: syz-executor.4 Not tainted 6.1.0-rc4-syzkaller-00356-g8f2975c2bb4c #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 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:2177 check_prev_add kernel/locking/lockdep.c:3097 [inline] check_prevs_add kernel/locking/lockdep.c:3216 [inline] validate_chain kernel/locking/lockdep.c:3831 [inline] __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055 lock_acquire kernel/locking/lockdep.c:5668 [inline] lock_acquire+0x1df/0x630 kernel/locking/lockdep.c:5633 del_timer_sync+0x5b/0x1b0 kernel/time/timer.c:1417 throtl_pd_free+0x15/0x40 block/blk-throttle.c:493 blkcg_deactivate_policy block/blk-cgroup.c:1471 [inline] blkcg_deactivate_policy+0x26c/0x470 block/blk-cgroup.c:1449 blk_throtl_exit+0xb3/0x1e0 block/blk-throttle.c:2406 blkcg_init_disk+0x1ee/0x6a0 block/blk-cgroup.c:1262 __alloc_disk_node+0x29d/0x650 block/genhd.c:1380 __blk_mq_alloc_disk+0x13b/0x1f0 block/blk-mq.c:4035 loop_add+0x3e2/0xaf0 drivers/block/loop.c:1983 loop_control_ioctl+0x133/0x620 drivers/block/loop.c:2155 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+0x63/0xcd RIP: 0033:0x7f1ee288b639 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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:00007f1ee360e168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f1ee29ac120 RCX: 00007f1ee288b639 RDX: 0000000000000000 RSI: 0000000000004c80 RDI: 0000000000000006 RBP: 00007f1ee360e1d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007f1ee2acfb1f R14: 00007f1ee360e300 R15: 0000000000022000