====================================================== WARNING: possible circular locking dependency detected 6.1.16-syzkaller #0 Not tainted ------------------------------------------------------ udevd/2538 is trying to acquire lock: ffff8880217e19c0 (&q->queue_lock){..-.}-{2:2}, at: spin_lock_irq include/linux/spinlock.h:375 [inline] ffff8880217e19c0 (&q->queue_lock){..-.}-{2:2}, at: throtl_pending_timer_fn+0x10d/0x1be0 block/blk-throttle.c:1193 but task is already holding lock: ffffc900001e0bc0 ((&sq->pending_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:41 [inline] ffffc900001e0bc0 ((&sq->pending_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbd/0x840 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+0x23a/0x630 kernel/locking/lockdep.c:5669 del_timer_sync+0x111/0x2e0 kernel/time/timer.c:1417 throtl_pd_free+0x15/0x40 block/blk-throttle.c:493 blkcg_deactivate_policy+0x32d/0x550 block/blk-cgroup.c:1499 blk_throtl_exit+0xa6/0x140 block/blk-throttle.c:2406 disk_release+0x1dd/0x380 block/genhd.c:1171 device_release+0x91/0x1c0 kobject_cleanup lib/kobject.c:681 [inline] kobject_release lib/kobject.c:712 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x224/0x460 lib/kobject.c:729 do_floppy_init+0x373/0xc59 drivers/block/floppy.c:4758 async_run_entry_fn+0xa2/0x410 kernel/async.c:127 process_one_work+0x909/0x1380 kernel/workqueue.c:2289 worker_thread+0xa5f/0x1210 kernel/workqueue.c:2436 kthread+0x268/0x300 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 -> #1 (&blkcg->lock){....}-{2:2}: lock_acquire+0x23a/0x630 kernel/locking/lockdep.c:5669 __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+0xa94/0x1280 block/blk-cgroup.c:336 blkcg_init_disk+0xee/0x350 block/blk-cgroup.c:1260 __alloc_disk_node+0x2ce/0x590 block/genhd.c:1385 __blk_alloc_disk+0x2c/0x80 block/genhd.c:1424 brd_alloc+0x2f9/0x6a0 drivers/block/brd.c:397 brd_init+0x100/0x1c2 drivers/block/brd.c:484 do_one_initcall+0x2d6/0xa80 init/main.c:1303 do_initcall_level+0x157/0x207 init/main.c:1376 do_initcalls+0x49/0x86 init/main.c:1392 kernel_init_freeable+0x473/0x61f init/main.c:1631 kernel_init+0x19/0x290 init/main.c:1519 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306 -> #0 (&q->queue_lock){..-.}-{2:2}: check_prev_add kernel/locking/lockdep.c:3098 [inline] check_prevs_add kernel/locking/lockdep.c:3217 [inline] validate_chain+0x1667/0x58e0 kernel/locking/lockdep.c:3832 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056 lock_acquire+0x23a/0x630 kernel/locking/lockdep.c:5669 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline] _raw_spin_lock_irq+0xcf/0x110 kernel/locking/spinlock.c:170 spin_lock_irq include/linux/spinlock.h:375 [inline] throtl_pending_timer_fn+0x10d/0x1be0 block/blk-throttle.c:1193 call_timer_fn+0x200/0x840 kernel/time/timer.c:1474 expire_timers kernel/time/timer.c:1519 [inline] __run_timers+0x67c/0x890 kernel/time/timer.c:1790 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1803 __do_softirq+0x30d/0xb1b kernel/softirq.c:571 invoke_softirq kernel/softirq.c:445 [inline] __irq_exit_rcu+0x155/0x240 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:1107 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:649 orc_ip arch/x86/kernel/unwind_orc.c:30 [inline] __orc_find arch/x86/kernel/unwind_orc.c:52 [inline] orc_find arch/x86/kernel/unwind_orc.c:178 [inline] unwind_next_frame+0x4a6/0x2220 arch/x86/kernel/unwind_orc.c:448 arch_stack_walk+0x10d/0x140 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x113/0x1c0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 __kasan_slab_alloc+0x65/0x70 mm/kasan/common.c:328 kasan_slab_alloc include/linux/kasan.h:201 [inline] slab_post_alloc_hook+0x50/0x370 mm/slab.h:737 slab_alloc_node mm/slub.c:3398 [inline] slab_alloc mm/slub.c:3406 [inline] __kmem_cache_alloc_lru mm/slub.c:3413 [inline] kmem_cache_alloc+0x119/0x260 mm/slub.c:3422 skb_clone+0x1e5/0x360 net/core/skbuff.c:1650 do_one_broadcast net/netlink/af_netlink.c:1459 [inline] netlink_broadcast+0x667/0x1160 net/netlink/af_netlink.c:1525 netlink_sendmsg+0x8f3/0xd60 net/netlink/af_netlink.c:1929 sock_sendmsg_nosec net/socket.c:716 [inline] sock_sendmsg net/socket.c:736 [inline] ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2482 ___sys_sendmsg net/socket.c:2536 [inline] __sys_sendmsg+0x2a9/0x390 net/socket.c:2565 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 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 udevd/2538: #0: ffffc900001e0bc0 ((&sq->pending_timer)){+.-.}-{0:0}, at: lockdep_copy_map include/linux/lockdep.h:41 [inline] #0: ffffc900001e0bc0 ((&sq->pending_timer)){+.-.}-{0:0}, at: call_timer_fn+0xbd/0x840 kernel/time/timer.c:1464 stack backtrace: CPU: 1 PID: 2538 Comm: udevd Not tainted 6.1.16-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106 check_noncircular+0x2fa/0x3b0 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+0x1667/0x58e0 kernel/locking/lockdep.c:3832 __lock_acquire+0x125b/0x1f80 kernel/locking/lockdep.c:5056 lock_acquire+0x23a/0x630 kernel/locking/lockdep.c:5669 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline] _raw_spin_lock_irq+0xcf/0x110 kernel/locking/spinlock.c:170 spin_lock_irq include/linux/spinlock.h:375 [inline] throtl_pending_timer_fn+0x10d/0x1be0 block/blk-throttle.c:1193 call_timer_fn+0x200/0x840 kernel/time/timer.c:1474 expire_timers kernel/time/timer.c:1519 [inline] __run_timers+0x67c/0x890 kernel/time/timer.c:1790 run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1803 __do_softirq+0x30d/0xb1b kernel/softirq.c:571 invoke_softirq kernel/softirq.c:445 [inline] __irq_exit_rcu+0x155/0x240 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:1107 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:649 RIP: 0010:orc_ip arch/x86/kernel/unwind_orc.c:30 [inline] RIP: 0010:__orc_find arch/x86/kernel/unwind_orc.c:52 [inline] RIP: 0010:orc_find arch/x86/kernel/unwind_orc.c:178 [inline] RIP: 0010:unwind_next_frame+0x4a6/0x2220 arch/x86/kernel/unwind_orc.c:448 Code: f9 02 48 c1 e8 3f 48 01 c8 48 83 e0 fe 49 8d 1c 47 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 0f b6 04 08 84 c0 75 27 <48> 63 03 48 01 d8 48 8d 4b 04 4c 39 e8 4c 0f 46 f9 48 8d 43 fc 48 RSP: 0018:ffffc9000966f360 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffffffff8ec20dd0 RCX: dffffc0000000000 RDX: ffffffff8f5d3d60 RSI: ffffffff8a89715d RDI: dffffc0000000000 RBP: ffffffff8ec20de8 R08: 000000000000000d R09: ffffc9000966f530 R10: 0000000000000000 R11: dffffc0000000001 R12: ffffffff8ec20db8 R13: ffffffff8a89715c R14: ffffffff8ec20db8 R15: ffffffff8ec20db8 arch_stack_walk+0x10d/0x140 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x113/0x1c0 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 __kasan_slab_alloc+0x65/0x70 mm/kasan/common.c:328 kasan_slab_alloc include/linux/kasan.h:201 [inline] slab_post_alloc_hook+0x50/0x370 mm/slab.h:737 slab_alloc_node mm/slub.c:3398 [inline] slab_alloc mm/slub.c:3406 [inline] __kmem_cache_alloc_lru mm/slub.c:3413 [inline] kmem_cache_alloc+0x119/0x260 mm/slub.c:3422 skb_clone+0x1e5/0x360 net/core/skbuff.c:1650 do_one_broadcast net/netlink/af_netlink.c:1459 [inline] netlink_broadcast+0x667/0x1160 net/netlink/af_netlink.c:1525 netlink_sendmsg+0x8f3/0xd60 net/netlink/af_netlink.c:1929 sock_sendmsg_nosec net/socket.c:716 [inline] sock_sendmsg net/socket.c:736 [inline] ____sys_sendmsg+0x59e/0x8f0 net/socket.c:2482 ___sys_sendmsg net/socket.c:2536 [inline] __sys_sendmsg+0x2a9/0x390 net/socket.c:2565 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 RIP: 0033:0x7fd58ddba163 Code: 64 89 02 48 c7 c0 ff ff ff ff eb b7 66 2e 0f 1f 84 00 00 00 00 00 90 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 55 c3 0f 1f 40 00 48 83 ec 28 89 54 24 1c 48 RSP: 002b:00007ffca6e96d38 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 0000561944435d10 RCX: 00007fd58ddba163 RDX: 0000000000000000 RSI: 00007ffca6e96d48 RDI: 000000000000000c RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000000 R13: 00000000000000a6 R14: 0000000000000000 R15: 000056194440c910 ---------------- Code disassembly (best guess): 0: f9 stc 1: 02 48 c1 add -0x3f(%rax),%cl 4: e8 3f 48 01 c8 callq 0xc8014848 9: 48 83 e0 fe and $0xfffffffffffffffe,%rax d: 49 8d 1c 47 lea (%r15,%rax,2),%rbx 11: 48 89 d8 mov %rbx,%rax 14: 48 c1 e8 03 shr $0x3,%rax 18: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx 1f: fc ff df 22: 0f b6 04 08 movzbl (%rax,%rcx,1),%eax 26: 84 c0 test %al,%al 28: 75 27 jne 0x51 * 2a: 48 63 03 movslq (%rbx),%rax <-- trapping instruction 2d: 48 01 d8 add %rbx,%rax 30: 48 8d 4b 04 lea 0x4(%rbx),%rcx 34: 4c 39 e8 cmp %r13,%rax 37: 4c 0f 46 f9 cmovbe %rcx,%r15 3b: 48 8d 43 fc lea -0x4(%rbx),%rax 3f: 48 rex.W