======================================================
WARNING: possible circular locking dependency detected
5.4.0-rc2+ #0 Not tainted
------------------------------------------------------
syz-executor521/9086 is trying to acquire lock:
ffff8880983c2fd8 (&mm->mmap_sem#2){++++}, at: __might_fault+0xfb/0x1e0 mm/memory.c:4449

but task is already holding lock:
ffff8880a7aead00 (&rp->fetch_lock){+.+.}, at: mon_bin_fetch+0x37/0x340 drivers/usb/mon/mon_bin.c:909

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&rp->fetch_lock){+.+.}:
       __mutex_lock_common kernel/locking/mutex.c:956 [inline]
       __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103
       mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1118
       mon_bin_vma_fault+0x73/0x2d0 drivers/usb/mon/mon_bin.c:1237
       __do_fault+0x111/0x540 mm/memory.c:3092
       do_cow_fault mm/memory.c:3518 [inline]
       do_fault mm/memory.c:3620 [inline]
       handle_pte_fault mm/memory.c:3849 [inline]
       __handle_mm_fault+0xce8/0x4040 mm/memory.c:3973
       handle_mm_fault+0x3b7/0xaa0 mm/memory.c:4010
       do_user_addr_fault arch/x86/mm/fault.c:1441 [inline]
       __do_page_fault+0x536/0xdd0 arch/x86/mm/fault.c:1506
       do_page_fault+0x38/0x590 arch/x86/mm/fault.c:1530
       page_fault+0x39/0x40 arch/x86/entry/entry_64.S:1202

-> #0 (&mm->mmap_sem#2){++++}:
       check_prev_add kernel/locking/lockdep.c:2476 [inline]
       check_prevs_add kernel/locking/lockdep.c:2581 [inline]
       validate_chain kernel/locking/lockdep.c:2971 [inline]
       __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955
       lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
       __might_fault mm/memory.c:4450 [inline]
       __might_fault+0x15e/0x1e0 mm/memory.c:4435
       mon_bin_fetch+0x26f/0x340 drivers/usb/mon/mon_bin.c:928
       mon_bin_ioctl+0x21e/0xc80 drivers/usb/mon/mon_bin.c:1091
       vfs_ioctl fs/ioctl.c:46 [inline]
       file_ioctl fs/ioctl.c:509 [inline]
       do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
       ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
       __do_sys_ioctl fs/ioctl.c:720 [inline]
       __se_sys_ioctl fs/ioctl.c:718 [inline]
       __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
       do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
       entry_SYSCALL_64_after_hwframe+0x49/0xbe

other info that might help us debug this:

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&rp->fetch_lock);
                               lock(&mm->mmap_sem#2);
                               lock(&rp->fetch_lock);
  lock(&mm->mmap_sem#2);

 *** DEADLOCK ***

1 lock held by syz-executor521/9086:
 #0: ffff8880a7aead00 (&rp->fetch_lock){+.+.}, at: mon_bin_fetch+0x37/0x340 drivers/usb/mon/mon_bin.c:909

stack backtrace:
CPU: 0 PID: 9086 Comm: syz-executor521 Not tainted 5.4.0-rc2+ #0
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_circular_bug.isra.0.cold+0x163/0x172 kernel/locking/lockdep.c:1685
 check_noncircular+0x32e/0x3e0 kernel/locking/lockdep.c:1809
 check_prev_add kernel/locking/lockdep.c:2476 [inline]
 check_prevs_add kernel/locking/lockdep.c:2581 [inline]
 validate_chain kernel/locking/lockdep.c:2971 [inline]
 __lock_acquire+0x2596/0x4a00 kernel/locking/lockdep.c:3955
 lock_acquire+0x190/0x410 kernel/locking/lockdep.c:4487
 __might_fault mm/memory.c:4450 [inline]
 __might_fault+0x15e/0x1e0 mm/memory.c:4435
 mon_bin_fetch+0x26f/0x340 drivers/usb/mon/mon_bin.c:928
 mon_bin_ioctl+0x21e/0xc80 drivers/usb/mon/mon_bin.c:1091
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
 do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x44a849
Code: e8 ec b6 02 00 48 83 c4 18 c3 0f 1f 80 00 00 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 0f 83 cb cc fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fe27b036ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 000000000044a849
RDX: 0000000020000140 RSI: 00000000c0109207 RDI: 0000000000000003
RBP: 00000000006dbc30 R08: 00007fe27b037700 R09: 0000000000000000
R10: 00007fe27b037700 R11: 0000000000000246 R12: 00000000006dbc3c
R13: 00007ffc3b6e7aef R14: 00007fe27b0379c0 R15: 0000000000000001