=====================================================
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
5.2.0-rc6+ #61 Not tainted
-----------------------------------------------------
syz-executor.0/26907 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
0000000098d02598 (&fiq->waitq){+.+.}, at: spin_lock include/linux/spinlock.h:338 [inline]
0000000098d02598 (&fiq->waitq){+.+.}, at: aio_poll fs/aio.c:1752 [inline]
0000000098d02598 (&fiq->waitq){+.+.}, at: __io_submit_one fs/aio.c:1826 [inline]
0000000098d02598 (&fiq->waitq){+.+.}, at: io_submit_one+0xefa/0x2ef0 fs/aio.c:1863

and this task is already holding:
000000003342e131 (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq include/linux/spinlock.h:363 [inline]
000000003342e131 (&(&ctx->ctx_lock)->rlock){..-.}, at: aio_poll fs/aio.c:1750 [inline]
000000003342e131 (&(&ctx->ctx_lock)->rlock){..-.}, at: __io_submit_one fs/aio.c:1826 [inline]
000000003342e131 (&(&ctx->ctx_lock)->rlock){..-.}, at: io_submit_one+0xeb5/0x2ef0 fs/aio.c:1863
which would create a new lock dependency:
 (&(&ctx->ctx_lock)->rlock){..-.} -> (&fiq->waitq){+.+.}

but this new dependency connects a SOFTIRQ-irq-safe lock:
 (&(&ctx->ctx_lock)->rlock){..-.}

... which became SOFTIRQ-irq-safe at:
  lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4303
  __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:620
  percpu_ref_put_many include/linux/percpu-refcount.h:285 [inline]
  percpu_ref_put include/linux/percpu-refcount.h:301 [inline]
  percpu_ref_call_confirm_rcu lib/percpu-refcount.c:124 [inline]
  percpu_ref_switch_to_atomic_rcu+0x407/0x540 lib/percpu-refcount.c:159
  __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
  rcu_do_batch kernel/rcu/tree.c:2092 [inline]
  invoke_rcu_callbacks kernel/rcu/tree.c:2310 [inline]
  rcu_core+0xba5/0x1500 kernel/rcu/tree.c:2291
  __do_softirq+0x25c/0x94c kernel/softirq.c:292
  run_ksoftirqd kernel/softirq.c:603 [inline]
  run_ksoftirqd+0x8e/0x110 kernel/softirq.c:595
  smpboot_thread_fn+0x6a3/0xa30 kernel/smpboot.c:165
  kthread+0x354/0x420 kernel/kthread.c:255
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

to a SOFTIRQ-irq-unsafe lock:
 (&fiq->waitq){+.+.}

... which became SOFTIRQ-irq-unsafe at:
...
  lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4303
  __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+0x2d1/0x580 fs/fuse/dev.c:676
  fuse_request_send_background+0x58/0x110 fs/fuse/dev.c:687
  fuse_send_init fs/fuse/inode.c:986 [inline]
  fuse_fill_super+0x13b4/0x1720 fs/fuse/inode.c:1211
  mount_nodev+0x66/0x110 fs/super.c:1392
  fuse_mount+0x2d/0x40 fs/fuse/inode.c:1236
  legacy_get_tree+0x108/0x220 fs/fs_context.c:661
  vfs_get_tree+0x8e/0x390 fs/super.c:1476
  do_new_mount fs/namespace.c:2791 [inline]
  do_mount+0x138c/0x1c00 fs/namespace.c:3111
  ksys_mount+0xdb/0x150 fs/namespace.c:3320
  __do_sys_mount fs/namespace.c:3334 [inline]
  __se_sys_mount fs/namespace.c:3331 [inline]
  __x64_sys_mount+0xbe/0x150 fs/namespace.c:3331
  do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

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 ***

1 lock held by syz-executor.0/26907:
 #0: 000000003342e131 (&(&ctx->ctx_lock)->rlock){..-.}, at: spin_lock_irq include/linux/spinlock.h:363 [inline]
 #0: 000000003342e131 (&(&ctx->ctx_lock)->rlock){..-.}, at: aio_poll fs/aio.c:1750 [inline]
 #0: 000000003342e131 (&(&ctx->ctx_lock)->rlock){..-.}, at: __io_submit_one fs/aio.c:1826 [inline]
 #0: 000000003342e131 (&(&ctx->ctx_lock)->rlock){..-.}, at: io_submit_one+0xeb5/0x2ef0 fs/aio.c:1863

the dependencies between SOFTIRQ-irq-safe lock and the holding lock:
-> (&(&ctx->ctx_lock)->rlock){..-.} {
   IN-SOFTIRQ-W at:
                    lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4303
                    __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:620
                    percpu_ref_put_many include/linux/percpu-refcount.h:285 [inline]
                    percpu_ref_put include/linux/percpu-refcount.h:301 [inline]
                    percpu_ref_call_confirm_rcu lib/percpu-refcount.c:124 [inline]
                    percpu_ref_switch_to_atomic_rcu+0x407/0x540 lib/percpu-refcount.c:159
                    __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
                    rcu_do_batch kernel/rcu/tree.c:2092 [inline]
                    invoke_rcu_callbacks kernel/rcu/tree.c:2310 [inline]
                    rcu_core+0xba5/0x1500 kernel/rcu/tree.c:2291
                    __do_softirq+0x25c/0x94c kernel/softirq.c:292
                    run_ksoftirqd kernel/softirq.c:603 [inline]
                    run_ksoftirqd+0x8e/0x110 kernel/softirq.c:595
                    smpboot_thread_fn+0x6a3/0xa30 kernel/smpboot.c:165
                    kthread+0x354/0x420 kernel/kthread.c:255
                    ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
   INITIAL USE at:
                   lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4303
                   __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:620
                   percpu_ref_put_many include/linux/percpu-refcount.h:285 [inline]
                   percpu_ref_put include/linux/percpu-refcount.h:301 [inline]
                   percpu_ref_call_confirm_rcu lib/percpu-refcount.c:124 [inline]
                   percpu_ref_switch_to_atomic_rcu+0x407/0x540 lib/percpu-refcount.c:159
                   __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
                   rcu_do_batch kernel/rcu/tree.c:2092 [inline]
                   invoke_rcu_callbacks kernel/rcu/tree.c:2310 [inline]
                   rcu_core+0xba5/0x1500 kernel/rcu/tree.c:2291
                   __do_softirq+0x25c/0x94c kernel/softirq.c:292
                   run_ksoftirqd kernel/softirq.c:603 [inline]
                   run_ksoftirqd+0x8e/0x110 kernel/softirq.c:595
                   smpboot_thread_fn+0x6a3/0xa30 kernel/smpboot.c:165
                   kthread+0x354/0x420 kernel/kthread.c:255
                   ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
 }
 ... key      at: [<ffffffff8a67b220>] __key.53435+0x0/0x40
 ... acquired at:
   lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4303
   __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:1752 [inline]
   __io_submit_one fs/aio.c:1826 [inline]
   io_submit_one+0xefa/0x2ef0 fs/aio.c:1863
   __do_sys_io_submit fs/aio.c:1922 [inline]
   __se_sys_io_submit fs/aio.c:1892 [inline]
   __x64_sys_io_submit+0x1bd/0x570 fs/aio.c:1892
   do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
   entry_SYSCALL_64_after_hwframe+0x49/0xbe


the dependencies between the lock to be acquired
 and SOFTIRQ-irq-unsafe lock:
-> (&fiq->waitq){+.+.} {
   HARDIRQ-ON-W at:
                    lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4303
                    __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+0x2d1/0x580 fs/fuse/dev.c:676
                    fuse_request_send_background+0x58/0x110 fs/fuse/dev.c:687
                    fuse_send_init fs/fuse/inode.c:986 [inline]
                    fuse_fill_super+0x13b4/0x1720 fs/fuse/inode.c:1211
                    mount_nodev+0x66/0x110 fs/super.c:1392
                    fuse_mount+0x2d/0x40 fs/fuse/inode.c:1236
                    legacy_get_tree+0x108/0x220 fs/fs_context.c:661
                    vfs_get_tree+0x8e/0x390 fs/super.c:1476
                    do_new_mount fs/namespace.c:2791 [inline]
                    do_mount+0x138c/0x1c00 fs/namespace.c:3111
                    ksys_mount+0xdb/0x150 fs/namespace.c:3320
                    __do_sys_mount fs/namespace.c:3334 [inline]
                    __se_sys_mount fs/namespace.c:3331 [inline]
                    __x64_sys_mount+0xbe/0x150 fs/namespace.c:3331
                    do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
                    entry_SYSCALL_64_after_hwframe+0x49/0xbe
   SOFTIRQ-ON-W at:
                    lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4303
                    __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+0x2d1/0x580 fs/fuse/dev.c:676
                    fuse_request_send_background+0x58/0x110 fs/fuse/dev.c:687
                    fuse_send_init fs/fuse/inode.c:986 [inline]
                    fuse_fill_super+0x13b4/0x1720 fs/fuse/inode.c:1211
                    mount_nodev+0x66/0x110 fs/super.c:1392
                    fuse_mount+0x2d/0x40 fs/fuse/inode.c:1236
                    legacy_get_tree+0x108/0x220 fs/fs_context.c:661
                    vfs_get_tree+0x8e/0x390 fs/super.c:1476
                    do_new_mount fs/namespace.c:2791 [inline]
                    do_mount+0x138c/0x1c00 fs/namespace.c:3111
                    ksys_mount+0xdb/0x150 fs/namespace.c:3320
                    __do_sys_mount fs/namespace.c:3334 [inline]
                    __se_sys_mount fs/namespace.c:3331 [inline]
                    __x64_sys_mount+0xbe/0x150 fs/namespace.c:3331
                    do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
                    entry_SYSCALL_64_after_hwframe+0x49/0xbe
   INITIAL USE at:
                   lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4303
                   __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+0x2d1/0x580 fs/fuse/dev.c:676
                   fuse_request_send_background+0x58/0x110 fs/fuse/dev.c:687
                   fuse_send_init fs/fuse/inode.c:986 [inline]
                   fuse_fill_super+0x13b4/0x1720 fs/fuse/inode.c:1211
                   mount_nodev+0x66/0x110 fs/super.c:1392
                   fuse_mount+0x2d/0x40 fs/fuse/inode.c:1236
                   legacy_get_tree+0x108/0x220 fs/fs_context.c:661
                   vfs_get_tree+0x8e/0x390 fs/super.c:1476
                   do_new_mount fs/namespace.c:2791 [inline]
                   do_mount+0x138c/0x1c00 fs/namespace.c:3111
                   ksys_mount+0xdb/0x150 fs/namespace.c:3320
                   __do_sys_mount fs/namespace.c:3334 [inline]
                   __se_sys_mount fs/namespace.c:3331 [inline]
                   __x64_sys_mount+0xbe/0x150 fs/namespace.c:3331
                   do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
                   entry_SYSCALL_64_after_hwframe+0x49/0xbe
 }
 ... key      at: [<ffffffff8a715140>] __key.44051+0x0/0x40
 ... acquired at:
   lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4303
   __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:1752 [inline]
   __io_submit_one fs/aio.c:1826 [inline]
   io_submit_one+0xefa/0x2ef0 fs/aio.c:1863
   __do_sys_io_submit fs/aio.c:1922 [inline]
   __se_sys_io_submit fs/aio.c:1892 [inline]
   __x64_sys_io_submit+0x1bd/0x570 fs/aio.c:1892
   do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
   entry_SYSCALL_64_after_hwframe+0x49/0xbe


stack backtrace:
CPU: 0 PID: 26907 Comm: syz-executor.0 Not tainted 5.2.0-rc6+ #61
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x172/0x1f0 lib/dump_stack.c:113
 print_bad_irq_dependency kernel/locking/lockdep.c:1920 [inline]
 check_irq_usage.cold+0x711/0xba0 kernel/locking/lockdep.c:2114
 check_prev_add kernel/locking/lockdep.c:2315 [inline]
 check_prevs_add kernel/locking/lockdep.c:2418 [inline]
 validate_chain kernel/locking/lockdep.c:2800 [inline]
 __lock_acquire+0x2469/0x5490 kernel/locking/lockdep.c:3793
 lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:4303
 __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:1752 [inline]
 __io_submit_one fs/aio.c:1826 [inline]
 io_submit_one+0xefa/0x2ef0 fs/aio.c:1863
 __do_sys_io_submit fs/aio.c:1922 [inline]
 __se_sys_io_submit fs/aio.c:1892 [inline]
 __x64_sys_io_submit+0x1bd/0x570 fs/aio.c:1892
 do_syscall_64+0xfd/0x680 arch/x86/entry/common.c:301
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x459519
Code: fd b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 cb b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb111cecc78 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459519
RDX: 0000000020000040 RSI: 0000000000000001 RDI: 00007fb111ccc000
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb111ced6d4
R13: 00000000004c0898 R14: 00000000004d3548 R15: 00000000ffffffff