======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.4203/20137 is trying to acquire lock:
ffff888144f100d0 (&q->queue_lock){..-.}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:376 [inline]
ffff888144f100d0 (&q->queue_lock){..-.}-{2:2}, at: throtl_pending_timer_fn+0x10e/0x1dd0 block/blk-throttle.c:1200
but task is already holding lock:
ffffc900001e0bc0 ((&sq->pending_timer)){+.-.}-{0:0}, at: call_timer_fn+0xcf/0x670 kernel/time/timer.c:1698
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #2 ((&sq->pending_timer)){+.-.}-{0:0}:
__timer_delete_sync+0xe1/0x2e0 kernel/time/timer.c:1556
del_timer_sync include/linux/timer.h:200 [inline]
throtl_pd_free+0x15/0x40 block/blk-throttle.c:493
blkcg_deactivate_policy+0x35c/0x5c0 block/blk-cgroup.c:1533
blk_throtl_exit+0xa6/0x140 block/blk-throttle.c:2415
blkcg_init_disk+0x37b/0x3f0 block/blk-cgroup.c:1310
__alloc_disk_node+0x2b3/0x570 block/genhd.c:1432
__blk_alloc_disk+0x2c/0x80 block/genhd.c:1471
alloc_dev drivers/md/dm.c:2055 [inline]
dm_create+0x46b/0xf90 drivers/md/dm.c:2259
dev_create+0x12e/0x2c0 drivers/md/dm-ioctl.c:875
ctl_ioctl drivers/md/dm-ioctl.c:2055 [inline]
dm_ctl_ioctl+0xa9c/0xec0 drivers/md/dm-ioctl.c:2077
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
-> #1 (&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:351 [inline]
blkg_create+0xbe9/0x13c0 block/blk-cgroup.c:322
blkcg_init_disk+0x28c/0x3f0 block/blk-cgroup.c:1286
__alloc_disk_node+0x2b3/0x570 block/genhd.c:1432
__blk_alloc_disk+0x2c/0x80 block/genhd.c:1471
brd_alloc+0x377/0x760 drivers/block/brd.c:424
brd_init+0x125/0x1a5 drivers/block/brd.c:529
do_one_initcall+0x257/0x800 init/main.c:1270
do_initcall_level+0x13d/0x1ed init/main.c:1343
do_initcalls+0x4b/0x8a init/main.c:1359
kernel_init_freeable+0x401/0x5ab init/main.c:1598
kernel_init+0x19/0x1b0 init/main.c:1486
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
-> #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 kernel/locking/lockdep.c:3830 [inline]
__lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063
lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5678
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
_raw_spin_lock_irq+0xab/0xf0 kernel/locking/spinlock.c:170
spin_lock_irq include/linux/spinlock.h:376 [inline]
throtl_pending_timer_fn+0x10e/0x1dd0 block/blk-throttle.c:1200
call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
expire_timers kernel/time/timer.c:1752 [inline]
__run_timers+0x56c/0x810 kernel/time/timer.c:2023
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
handle_softirqs+0x291/0x910 kernel/softirq.c:596
__do_softirq kernel/softirq.c:630 [inline]
invoke_softirq kernel/softirq.c:470 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
free_percpu+0x89d/0xde0 mm/percpu.c:2312
blk_throtl_exit+0x114/0x140 block/blk-throttle.c:2417
disk_release+0x216/0x3a0 block/genhd.c:1218
device_release+0x92/0x1c0 drivers/base/core.c:-1
kobject_cleanup lib/kobject.c:681 [inline]
kobject_release lib/kobject.c:712 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x217/0x450 lib/kobject.c:729
loop_control_remove drivers/block/loop.c:2158 [inline]
loop_control_ioctl+0x499/0x590 drivers/block/loop.c:2196
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
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 ***
1 lock held by syz.4.4203/20137:
#0: ffffc900001e0bc0 ((&sq->pending_timer)){+.-.}-{0:0}, at: call_timer_fn+0xcf/0x670 kernel/time/timer.c:1698
stack backtrace:
CPU: 1 PID: 20137 Comm: syz.4.4203 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
check_noncircular+0x296/0x330 kernel/locking/lockdep.c:2170
check_prev_add kernel/locking/lockdep.c:3095 [inline]
check_prevs_add kernel/locking/lockdep.c:3214 [inline]
validate_chain kernel/locking/lockdep.c:3830 [inline]
__lock_acquire+0x2d18/0x7c40 kernel/locking/lockdep.c:5063
lock_acquire+0x1bb/0x4a0 kernel/locking/lockdep.c:5678
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
_raw_spin_lock_irq+0xab/0xf0 kernel/locking/spinlock.c:170
spin_lock_irq include/linux/spinlock.h:376 [inline]
throtl_pending_timer_fn+0x10e/0x1dd0 block/blk-throttle.c:1200
call_timer_fn+0x1ac/0x670 kernel/time/timer.c:1701
expire_timers kernel/time/timer.c:1752 [inline]
__run_timers+0x56c/0x810 kernel/time/timer.c:2023
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:2036
handle_softirqs+0x291/0x910 kernel/softirq.c:596
__do_softirq kernel/softirq.c:630 [inline]
invoke_softirq kernel/softirq.c:470 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 3f 1a 1c f7 65 8b 05 10 ca c5 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc90002f97b80 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: cbf9832a08b1ad00
RDX: dffffc0000000000 RSI: ffffffff8a8c18a0 RDI: 0000000000000001
RBP: ffffc90002f97c10 R08: ffffffff8cbebf03 R09: 1ffffffff197d7e0
R10: dffffc0000000000 R11: fffffbfff197d7e1 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffffffff8cbebf00 R15: 1ffff920005f2f70
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
free_percpu+0x89d/0xde0 mm/percpu.c:2312
blk_throtl_exit+0x114/0x140 block/blk-throttle.c:2417
disk_release+0x216/0x3a0 block/genhd.c:1218
device_release+0x92/0x1c0 drivers/base/core.c:-1
kobject_cleanup lib/kobject.c:681 [inline]
kobject_release lib/kobject.c:712 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x217/0x450 lib/kobject.c:729
loop_control_remove drivers/block/loop.c:2158 [inline]
loop_control_ioctl+0x499/0x590 drivers/block/loop.c:2196
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7faa3079e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007faa2e591028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007faa30a26270 RCX: 00007faa3079e159
RDX: 0000000000000000 RSI: 0000000000004c81 RDI: 0000000000000009
RBP: 00007faa3083506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007faa30a26308 R14: 00007faa30a26270 R15: 00007ffcc21536f8
----------------
Code disassembly (best guess):
0: c7 44 24 20 00 00 00 movl $0x0,0x20(%rsp)
7: 00
8: 9c pushf
9: 8f 44 24 20 pop 0x20(%rsp)
d: f7 44 24 20 00 02 00 testl $0x200,0x20(%rsp)
14: 00
15: 41 c6 04 07 f8 movb $0xf8,(%r15,%rax,1)
1a: 75 4b jne 0x67
1c: f7 c3 00 02 00 00 test $0x200,%ebx
22: 74 01 je 0x25
24: fb sti
25: bf 01 00 00 00 mov $0x1,%edi
* 2a: e8 3f 1a 1c f7 call 0xf71c1a6e <-- trapping instruction
2f: 65 8b 05 10 ca c5 75 mov %gs:0x75c5ca10(%rip),%eax # 0x75c5ca46
36: 85 c0 test %eax,%eax
38: 74 3c je 0x76
3a: 48 rex.W
3b: c7 .byte 0xc7
3c: 04 24 add $0x24,%al
3e: 0e (bad)
3f: 36 ss