====================================================== WARNING: possible circular locking dependency detected 6.0.0-rc6-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.4/8326 is trying to acquire lock: ffff888146f800d0 (&q->queue_lock){..-.}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:374 [inline] ffff888146f800d0 (&q->queue_lock){..-.}-{2:2}, at: throtl_pending_timer_fn+0xe9/0xfb0 block/blk-throttle.c:1152 but task is already holding lock: ffffc900001e0be0 ((&sq->pending_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:41 [inline] ffffc900001e0be0 ((&sq->pending_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbb/0x210 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+0x182/0x3c0 kernel/locking/lockdep.c:5666 del_timer_sync+0xec/0x2a0 kernel/time/timer.c:1417 throtl_pd_free+0x15/0x40 block/blk-throttle.c:500 blkcg_deactivate_policy+0x328/0x540 block/blk-cgroup.c:1523 blk_throtl_exit+0x86/0x120 block/blk-throttle.c:2337 blkcg_init_queue+0x281/0x300 block/blk-cgroup.c:1304 __alloc_disk_node+0x2ce/0x590 block/genhd.c:1366 __blk_mq_alloc_disk+0x11b/0x1e0 block/blk-mq.c:3942 loop_add+0x325/0x9b0 drivers/block/loop.c:1983 loop_control_ioctl+0x108/0x770 drivers/block/loop.c:2155 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #1 (&blkcg->lock){....}-{2:2}: lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5666 __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:349 [inline] blkg_create+0x949/0x10a0 block/blk-cgroup.c:344 blkcg_init_queue+0xb9/0x300 block/blk-cgroup.c:1285 __alloc_disk_node+0x2ce/0x590 block/genhd.c:1366 __blk_alloc_disk+0x2c/0x80 block/genhd.c:1405 brd_alloc+0x315/0x720 drivers/block/brd.c:391 brd_init+0x102/0x1c6 drivers/block/brd.c:477 do_one_initcall+0x1b9/0x3e0 init/main.c:1296 do_initcall_level+0x168/0x218 init/main.c:1369 do_initcalls+0x4b/0x8c init/main.c:1385 kernel_init_freeable+0x3f1/0x57b init/main.c:1623 kernel_init+0x19/0x2b0 init/main.c:1512 ret_from_fork+0x1f/0x30 -> #0 (&q->queue_lock){..-.}-{2:2}: check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain+0x1873/0x6c00 kernel/locking/lockdep.c:3829 __lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5053 lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5666 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline] _raw_spin_lock_irq+0xae/0xf0 kernel/locking/spinlock.c:170 spin_lock_irq include/linux/spinlock.h:374 [inline] throtl_pending_timer_fn+0xe9/0xfb0 block/blk-throttle.c:1152 call_timer_fn+0xf5/0x210 kernel/time/timer.c:1474 expire_timers kernel/time/timer.c:1519 [inline] __run_timers+0x772/0x980 kernel/time/timer.c:1790 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1803 __do_softirq+0x362/0x773 kernel/softirq.c:571 __irq_exit_rcu+0xcf/0x150 kernel/softirq.c:650 irq_exit_rcu+0x5/0x20 kernel/softirq.c:662 sysvec_apic_timer_interrupt+0x91/0xb0 arch/x86/kernel/apic/apic.c:1106 asm_sysvec_apic_timer_interrupt+0x16/0x20 native_save_fl arch/x86/include/asm/irqflags.h:35 [inline] arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline] arch_local_irq_save arch/x86/include/asm/irqflags.h:106 [inline] lock_is_held_type+0x62/0x180 kernel/locking/lockdep.c:5705 lock_is_held include/linux/lockdep.h:283 [inline] rcu_read_lock_sched_held+0x87/0x110 kernel/rcu/update.c:125 trace_lock_acquire+0x7f/0x1d0 include/trace/events/lock.h:24 lock_acquire+0xa4/0x3c0 kernel/locking/lockdep.c:5637 rcu_lock_acquire+0x20/0x30 include/linux/rcupdate.h:280 rcu_read_lock include/linux/rcupdate.h:706 [inline] folio_memcg_lock+0x8c/0x5b0 mm/memcontrol.c:2044 page_remove_rmap+0x2d/0x460 mm/rmap.c:1432 zap_pte_range+0x9c4/0x19b0 mm/memory.c:1454 zap_pmd_range+0x587/0x690 mm/memory.c:1575 zap_pud_range mm/memory.c:1604 [inline] zap_p4d_range mm/memory.c:1625 [inline] unmap_page_range+0x466/0x7a0 mm/memory.c:1646 unmap_vmas+0x1f7/0x380 mm/memory.c:1731 exit_mmap+0x1b4/0x520 mm/mmap.c:3116 __mmput+0x111/0x3a0 kernel/fork.c:1187 exit_mm+0x1ef/0x2c0 kernel/exit.c:510 do_exit+0x4e1/0x20a0 kernel/exit.c:782 do_group_exit+0x23b/0x2f0 kernel/exit.c:925 get_signal+0x172f/0x1780 kernel/signal.c:2857 arch_do_signal_or_restart+0x7b/0x730 arch/x86/kernel/signal.c:869 exit_to_user_mode_loop+0x74/0x150 kernel/entry/common.c:166 exit_to_user_mode_prepare+0xb2/0x140 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline] syscall_exit_to_user_mode+0x26/0x60 kernel/entry/common.c:294 do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd 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 *** 3 locks held by syz-executor.4/8326: #0: ffff8880779c7128 (&mm->mmap_lock#2){++++}-{3:3}, at: mmap_write_lock include/linux/mmap_lock.h:71 [inline] #0: ffff8880779c7128 (&mm->mmap_lock#2){++++}-{3:3}, at: exit_mmap+0x114/0x520 mm/mmap.c:3101 #1: ffff8880180c1a38 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:349 [inline] #1: ffff8880180c1a38 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: zap_pte_range+0x233/0x19b0 mm/memory.c:1418 #2: ffffc900001e0be0 ((&sq->pending_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:41 [inline] #2: ffffc900001e0be0 ((&sq->pending_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbb/0x210 kernel/time/timer.c:1464 stack backtrace: CPU: 1 PID: 8326 Comm: syz-executor.4 Not tainted 6.0.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106 check_noncircular+0x2cc/0x390 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+0x1873/0x6c00 kernel/locking/lockdep.c:3829 __lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5053 lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5666 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline] _raw_spin_lock_irq+0xae/0xf0 kernel/locking/spinlock.c:170 spin_lock_irq include/linux/spinlock.h:374 [inline] throtl_pending_timer_fn+0xe9/0xfb0 block/blk-throttle.c:1152 call_timer_fn+0xf5/0x210 kernel/time/timer.c:1474 expire_timers kernel/time/timer.c:1519 [inline] __run_timers+0x772/0x980 kernel/time/timer.c:1790 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1803 __do_softirq+0x362/0x773 kernel/softirq.c:571 __irq_exit_rcu+0xcf/0x150 kernel/softirq.c:650 irq_exit_rcu+0x5/0x20 kernel/softirq.c:662 sysvec_apic_timer_interrupt+0x91/0xb0 arch/x86/kernel/apic/apic.c:1106 asm_sysvec_apic_timer_interrupt+0x16/0x20 RIP: 0010:native_irq_disable arch/x86/include/asm/irqflags.h:40 [inline] RIP: 0010:arch_local_irq_disable arch/x86/include/asm/irqflags.h:75 [inline] RIP: 0010:arch_local_irq_save arch/x86/include/asm/irqflags.h:107 [inline] RIP: 0010:lock_is_held_type+0x62/0x180 kernel/locking/lockdep.c:5705 Code: 85 e6 00 00 00 65 4c 8b 2c 25 00 6f 02 00 41 83 bd 74 0a 00 00 00 0f 85 cf 00 00 00 41 89 f6 49 89 ff 9c 8f 04 24 4c 8b 24 24 48 c7 c7 60 9c 8d 8a e8 a1 14 00 00 65 ff 05 0a f3 df 75 41 83 RSP: 0018:ffffc9000b747098 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 1ffff920016e8e1c RCX: 0000000080000002 RDX: 0000000000000000 RSI: 00000000ffffffff RDI: ffffffff8cb231a0 RBP: 00000000ffffffff R08: dffffc0000000000 R09: fffffbfff1c1648e R10: fffffbfff1c1648e R11: 1ffffffff1c1648d R12: 0000000000000246 R13: ffff8880482a1d80 R14: 00000000ffffffff R15: ffffffff8cb231a0 lock_is_held include/linux/lockdep.h:283 [inline] rcu_read_lock_sched_held+0x87/0x110 kernel/rcu/update.c:125 trace_lock_acquire+0x7f/0x1d0 include/trace/events/lock.h:24 lock_acquire+0xa4/0x3c0 kernel/locking/lockdep.c:5637 rcu_lock_acquire+0x20/0x30 include/linux/rcupdate.h:280 rcu_read_lock include/linux/rcupdate.h:706 [inline] folio_memcg_lock+0x8c/0x5b0 mm/memcontrol.c:2044 page_remove_rmap+0x2d/0x460 mm/rmap.c:1432 zap_pte_range+0x9c4/0x19b0 mm/memory.c:1454 zap_pmd_range+0x587/0x690 mm/memory.c:1575 zap_pud_range mm/memory.c:1604 [inline] zap_p4d_range mm/memory.c:1625 [inline] unmap_page_range+0x466/0x7a0 mm/memory.c:1646 unmap_vmas+0x1f7/0x380 mm/memory.c:1731 exit_mmap+0x1b4/0x520 mm/mmap.c:3116 __mmput+0x111/0x3a0 kernel/fork.c:1187 exit_mm+0x1ef/0x2c0 kernel/exit.c:510 do_exit+0x4e1/0x20a0 kernel/exit.c:782 do_group_exit+0x23b/0x2f0 kernel/exit.c:925 get_signal+0x172f/0x1780 kernel/signal.c:2857 arch_do_signal_or_restart+0x7b/0x730 arch/x86/kernel/signal.c:869 exit_to_user_mode_loop+0x74/0x150 kernel/entry/common.c:166 exit_to_user_mode_prepare+0xb2/0x140 kernel/entry/common.c:201 __syscall_exit_to_user_mode_work kernel/entry/common.c:283 [inline] syscall_exit_to_user_mode+0x26/0x60 kernel/entry/common.c:294 do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f3ca8a89409 Code: Unable to access opcode bytes at RIP 0x7f3ca8a893df. RSP: 002b:00007f3ca9c93218 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 00007f3ca8b9bf88 RCX: 00007f3ca8a89409 RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007f3ca8b9bf88 RBP: 00007f3ca8b9bf80 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3ca8b9bf8c R13: 00007ffed5fc06bf R14: 00007f3ca9c93300 R15: 0000000000022000 ---------------- Code disassembly (best guess): 0: 85 e6 test %esp,%esi 2: 00 00 add %al,(%rax) 4: 00 65 4c add %ah,0x4c(%rbp) 7: 8b 2c 25 00 6f 02 00 mov 0x26f00,%ebp e: 41 83 bd 74 0a 00 00 cmpl $0x0,0xa74(%r13) 15: 00 16: 0f 85 cf 00 00 00 jne 0xeb 1c: 41 89 f6 mov %esi,%r14d 1f: 49 89 ff mov %rdi,%r15 22: 9c pushfq 23: 8f 04 24 popq (%rsp) 26: 4c 8b 24 24 mov (%rsp),%r12 * 2a: fa cli <-- trapping instruction 2b: 48 c7 c7 60 9c 8d 8a mov $0xffffffff8a8d9c60,%rdi 32: e8 a1 14 00 00 callq 0x14d8 37: 65 ff 05 0a f3 df 75 incl %gs:0x75dff30a(%rip) # 0x75dff348 3e: 41 rex.B 3f: 83 .byte 0x83