syzbot

========================================================
WARNING: possible irq lock inversion dependency detected
5.3.0+ #0 Not tainted
--------------------------------------------------------
swapper/1/0 just changed the state of lock:
ffff8880a1235b58 (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq include/linux/spinlock.h:363 [inline]
ffff8880a1235b58 (&(&ctx->ctx_lock)->rlock){..-.}, at: free_ioctx_users+0x2d/0x490 fs/aio.c:618
but this lock took another, SOFTIRQ-unsafe lock in the past:
 (&fiq->waitq){+.+.}


and interrupts could create inverse lock ordering between them.


other info that might help us debug this:
 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&fiq->waitq);
                               local_irq_disable();
                               lock(&(&ctx->ctx_lock)->rlock);
                               lock(&fiq->waitq);
  <Interrupt>
    lock(&(&ctx->ctx_lock)->rlock);

 *** DEADLOCK ***

2 locks held by swapper/1/0:
 #0: ffffffff88fab240 (rcu_callback){....}, at: __rcu_reclaim kernel/rcu/rcu.h:210 [inline]
 #0: ffffffff88fab240 (rcu_callback){....}, at: rcu_do_batch kernel/rcu/tree.c:2157 [inline]
 #0: ffffffff88fab240 (rcu_callback){....}, at: rcu_core+0x60e/0x1560 kernel/rcu/tree.c:2377
 #1: ffffffff88fab280 (rcu_read_lock_sched){....}, at: percpu_ref_call_confirm_rcu lib/percpu-refcount.c:126 [inline]
 #1: ffffffff88fab280 (rcu_read_lock_sched){....}, at: percpu_ref_switch_to_atomic_rcu+0x20e/0x570 lib/percpu-refcount.c:165

the shortest dependencies between 2nd lock and 1st lock:
 -> (&fiq->waitq){+.+.} {
    HARDIRQ-ON-W at:
                      lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
                      __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
                      _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151
                      spin_lock include/linux/spinlock.h:338 [inline]
                      flush_bg_queue+0x1f3/0x3c0 fs/fuse/dev.c:415
                      fuse_request_queue_background+0x2f8/0x5a0 fs/fuse/dev.c:676
                      fuse_request_send_background+0x58/0x110 fs/fuse/dev.c:687
                      cuse_send_init fs/fuse/cuse.c:459 [inline]
                      cuse_channel_open+0x5ba/0x830 fs/fuse/cuse.c:519
                      misc_open+0x395/0x4c0 drivers/char/misc.c:141
                      chrdev_open+0x245/0x6b0 fs/char_dev.c:414
                      do_dentry_open+0x4df/0x1250 fs/open.c:797
                      vfs_open+0xa0/0xd0 fs/open.c:906
                      do_last fs/namei.c:3408 [inline]
                      path_openat+0x10e9/0x4630 fs/namei.c:3525
                      do_filp_open+0x1a1/0x280 fs/namei.c:3555
                      do_sys_open+0x3fe/0x5d0 fs/open.c:1089
                      __do_sys_openat fs/open.c:1116 [inline]
                      __se_sys_openat fs/open.c:1110 [inline]
                      __x64_sys_openat+0x9d/0x100 fs/open.c:1110
                      do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
                      entry_SYSCALL_64_after_hwframe+0x49/0xbe
    SOFTIRQ-ON-W at:
                      lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
                      __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
                      _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151
                      spin_lock include/linux/spinlock.h:338 [inline]
                      flush_bg_queue+0x1f3/0x3c0 fs/fuse/dev.c:415
                      fuse_request_queue_background+0x2f8/0x5a0 fs/fuse/dev.c:676
                      fuse_request_send_background+0x58/0x110 fs/fuse/dev.c:687
                      cuse_send_init fs/fuse/cuse.c:459 [inline]
                      cuse_channel_open+0x5ba/0x830 fs/fuse/cuse.c:519
                      misc_open+0x395/0x4c0 drivers/char/misc.c:141
                      chrdev_open+0x245/0x6b0 fs/char_dev.c:414
                      do_dentry_open+0x4df/0x1250 fs/open.c:797
                      vfs_open+0xa0/0xd0 fs/open.c:906
                      do_last fs/namei.c:3408 [inline]
                      path_openat+0x10e9/0x4630 fs/namei.c:3525
                      do_filp_open+0x1a1/0x280 fs/namei.c:3555
                      do_sys_open+0x3fe/0x5d0 fs/open.c:1089
                      __do_sys_openat fs/open.c:1116 [inline]
                      __se_sys_openat fs/open.c:1110 [inline]
                      __x64_sys_openat+0x9d/0x100 fs/open.c:1110
                      do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
                      entry_SYSCALL_64_after_hwframe+0x49/0xbe
    INITIAL USE at:
                     lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
                     __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
                     _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151
                     spin_lock include/linux/spinlock.h:338 [inline]
                     flush_bg_queue+0x1f3/0x3c0 fs/fuse/dev.c:415
                     fuse_request_queue_background+0x2f8/0x5a0 fs/fuse/dev.c:676
                     fuse_request_send_background+0x58/0x110 fs/fuse/dev.c:687
                     cuse_send_init fs/fuse/cuse.c:459 [inline]
                     cuse_channel_open+0x5ba/0x830 fs/fuse/cuse.c:519
                     misc_open+0x395/0x4c0 drivers/char/misc.c:141
                     chrdev_open+0x245/0x6b0 fs/char_dev.c:414
                     do_dentry_open+0x4df/0x1250 fs/open.c:797
                     vfs_open+0xa0/0xd0 fs/open.c:906
                     do_last fs/namei.c:3408 [inline]
                     path_openat+0x10e9/0x4630 fs/namei.c:3525
                     do_filp_open+0x1a1/0x280 fs/namei.c:3555
                     do_sys_open+0x3fe/0x5d0 fs/open.c:1089
                     __do_sys_openat fs/open.c:1116 [inline]
                     __se_sys_openat fs/open.c:1110 [inline]
                     __x64_sys_openat+0x9d/0x100 fs/open.c:1110
                     do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
                     entry_SYSCALL_64_after_hwframe+0x49/0xbe
  }
  ... key      at: [<ffffffff8aba63c0>] __key.44672+0x0/0x40
  ... acquired at:
   __raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
   _raw_spin_lock+0x2f/0x40 kernel/locking/spinlock.c:151
   spin_lock include/linux/spinlock.h:338 [inline]
   aio_poll fs/aio.c:1751 [inline]
   __io_submit_one fs/aio.c:1825 [inline]
   io_submit_one+0xefa/0x2ef0 fs/aio.c:1862
   __do_sys_io_submit fs/aio.c:1921 [inline]
   __se_sys_io_submit fs/aio.c:1891 [inline]
   __x64_sys_io_submit+0x1bd/0x570 fs/aio.c:1891
   do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
   entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> (&(&ctx->ctx_lock)->rlock){..-.} {
   IN-SOFTIRQ-W at:
                    lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
                    __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
                    _raw_spin_lock_irq+0x60/0x80 kernel/locking/spinlock.c:167
                    spin_lock_irq include/linux/spinlock.h:363 [inline]
                    free_ioctx_users+0x2d/0x490 fs/aio.c:618
                    percpu_ref_put_many include/linux/percpu-refcount.h:293 [inline]
                    percpu_ref_put include/linux/percpu-refcount.h:309 [inline]
                    percpu_ref_call_confirm_rcu lib/percpu-refcount.c:130 [inline]
                    percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 lib/percpu-refcount.c:165
                    __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
                    rcu_do_batch kernel/rcu/tree.c:2157 [inline]
                    rcu_core+0x581/0x1560 kernel/rcu/tree.c:2377
                    rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2386
                    __do_softirq+0x262/0x98c kernel/softirq.c:292
                    invoke_softirq kernel/softirq.c:373 [inline]
                    irq_exit+0x19b/0x1e0 kernel/softirq.c:413
                    exiting_irq arch/x86/include/asm/apic.h:536 [inline]
                    smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1137
                    apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
                    native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60
                    arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:571
                    default_idle_call+0x84/0xb0 kernel/sched/idle.c:94
                    cpuidle_idle_call kernel/sched/idle.c:154 [inline]
                    do_idle+0x3b7/0x6e0 kernel/sched/idle.c:264
                    cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:356
                    start_secondary+0x2f4/0x410 arch/x86/kernel/smpboot.c:264
                    secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241
   INITIAL USE at:
                   lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
                   __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
                   _raw_spin_lock_irq+0x60/0x80 kernel/locking/spinlock.c:167
                   spin_lock_irq include/linux/spinlock.h:363 [inline]
                   aio_poll fs/aio.c:1749 [inline]
                   __io_submit_one fs/aio.c:1825 [inline]
                   io_submit_one+0xeb5/0x2ef0 fs/aio.c:1862
                   __do_sys_io_submit fs/aio.c:1921 [inline]
                   __se_sys_io_submit fs/aio.c:1891 [inline]
                   __x64_sys_io_submit+0x1bd/0x570 fs/aio.c:1891
                   do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
                   entry_SYSCALL_64_after_hwframe+0x49/0xbe
 }
 ... key      at: [<ffffffff8ab0c460>] __key.54293+0x0/0x40
 ... acquired at:
   mark_lock_irq kernel/locking/lockdep.c:3317 [inline]
   mark_lock+0x517/0x1220 kernel/locking/lockdep.c:3666
   mark_usage kernel/locking/lockdep.c:3566 [inline]
   __lock_acquire+0x1eaf/0x4e70 kernel/locking/lockdep.c:3909
   lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
   __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
   _raw_spin_lock_irq+0x60/0x80 kernel/locking/spinlock.c:167
   spin_lock_irq include/linux/spinlock.h:363 [inline]
   free_ioctx_users+0x2d/0x490 fs/aio.c:618
   percpu_ref_put_many include/linux/percpu-refcount.h:293 [inline]
   percpu_ref_put include/linux/percpu-refcount.h:309 [inline]
   percpu_ref_call_confirm_rcu lib/percpu-refcount.c:130 [inline]
   percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 lib/percpu-refcount.c:165
   __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
   rcu_do_batch kernel/rcu/tree.c:2157 [inline]
   rcu_core+0x581/0x1560 kernel/rcu/tree.c:2377
   rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2386
   __do_softirq+0x262/0x98c kernel/softirq.c:292
   invoke_softirq kernel/softirq.c:373 [inline]
   irq_exit+0x19b/0x1e0 kernel/softirq.c:413
   exiting_irq arch/x86/include/asm/apic.h:536 [inline]
   smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1137
   apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
   native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60
   arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:571
   default_idle_call+0x84/0xb0 kernel/sched/idle.c:94
   cpuidle_idle_call kernel/sched/idle.c:154 [inline]
   do_idle+0x3b7/0x6e0 kernel/sched/idle.c:264
   cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:356
   start_secondary+0x2f4/0x410 arch/x86/kernel/smpboot.c:264
   secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:241


stack backtrace:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.3.0+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_irq_inversion_bug.part.0+0x2e4/0x2f1 kernel/locking/lockdep.c:3179
 print_irq_inversion_bug kernel/locking/lockdep.c:3180 [inline]
 check_usage_forwards.cold+0x20/0x29 kernel/locking/lockdep.c:3204
 mark_lock_irq kernel/locking/lockdep.c:3317 [inline]
 mark_lock+0x517/0x1220 kernel/locking/lockdep.c:3666
 mark_usage kernel/locking/lockdep.c:3566 [inline]
 __lock_acquire+0x1eaf/0x4e70 kernel/locking/lockdep.c:3909
 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
 _raw_spin_lock_irq+0x60/0x80 kernel/locking/spinlock.c:167
 spin_lock_irq include/linux/spinlock.h:363 [inline]
 free_ioctx_users+0x2d/0x490 fs/aio.c:618
 percpu_ref_put_many include/linux/percpu-refcount.h:293 [inline]
 percpu_ref_put include/linux/percpu-refcount.h:309 [inline]
 percpu_ref_call_confirm_rcu lib/percpu-refcount.c:130 [inline]
 percpu_ref_switch_to_atomic_rcu+0x4c0/0x570 lib/percpu-refcount.c:165
 __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
 rcu_do_batch kernel/rcu/tree.c:2157 [inline]
 rcu_core+0x581/0x1560 kernel/rcu/tree.c:2377
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2386
 __do_softirq+0x262/0x98c kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0x19b/0x1e0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 smp_apic_timer_interrupt+0x1a3/0x610 arch/x86/kernel/apic/apic.c:1137
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
 </IRQ>
RIP: 0010:native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:61
Code: 38 8e 66 fa eb 8a 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d 54 25 61 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 44 25 61 00 fb f4 <c3> 90 55 48 89 e5 41 57 41 56 41 55 41 54 53 e8 9e 83 19 fa e8 b9
RSP: 0018:ffff8880a98e7d68 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: 1ffffffff11e630f RBX: ffff8880a98d4340 RCX: 0000000000000000
RDX: dffffc0000000000 RSI: 0000000000000006 RDI: ffff8880a98d4bd4
RBP: ffff8880a98e7d98 R08: ffff8880a98d4340 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: dffffc0000000000
R13: ffffffff89c6b5c0 R14: 0000000000000000 R15: 0000000000000001
 arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:571
 default_idle_call+0x84/0xb0 kernel/sched/idle.c:94
 cpuidle_idle_call kernel/sched/idle.c:154 [inline]
 do_idle+0x3b7/0x6e0 kernel/sched/idle.c:264
 cpu_startup_entry+0x1b/0x20 kernel/sched/idle.c:356
 start_secondary+0x2f4/0x410 arch/x86/kernel/smpboot.c:264
 ? set_cpu_sibling_map