======================================================
WARNING: possible circular locking dependency detected
5.4.0-rc2+ #0 Not tainted
------------------------------------------------------
syz-executor387/8017 is trying to acquire lock:
ffff888086d5d358 (&mm->mmap_sem#2){++++}, at: __might_fault+0xd2/0x160 mm/memory.c:4449

but task is already holding lock:
ffff8880a3558d00 (&rp->fetch_lock){+.+.}, at: mon_bin_fetch+0x34/0x300 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){+.+.}:
       lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4487
       __mutex_lock_common+0x14c/0x2e20 kernel/locking/mutex.c:956
       __mutex_lock kernel/locking/mutex.c:1103 [inline]
       mutex_lock_nested+0x1b/0x30 kernel/locking/mutex.c:1118
       mon_bin_vma_fault+0x6d/0x260 drivers/usb/mon/mon_bin.c:1237
       __do_fault+0x144/0x3d0 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 mm/memory.c:3973 [inline]
       handle_mm_fault+0x369f/0x5ff0 mm/memory.c:4010
       do_user_addr_fault+0x589/0xaf0 arch/x86/mm/fault.c:1441
       __do_page_fault+0xd3/0x1f0 arch/x86/mm/fault.c:1506
       do_page_fault+0x99/0xb0 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+0x161e/0x7bc0 kernel/locking/lockdep.c:2971
       __lock_acquire+0xc75/0x1be0 kernel/locking/lockdep.c:3955
       lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4487
       __might_fault+0xf5/0x160 mm/memory.c:4450
       mon_bin_fetch+0x193/0x300 drivers/usb/mon/mon_bin.c:928
       mon_bin_ioctl+0x7f6/0xc40 drivers/usb/mon/mon_bin.c:1091
       do_vfs_ioctl+0x744/0x1730 fs/ioctl.c:46
       ksys_ioctl fs/ioctl.c:713 [inline]
       __do_sys_ioctl fs/ioctl.c:720 [inline]
       __se_sys_ioctl fs/ioctl.c:718 [inline]
       __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:718
       do_syscall_64+0xf7/0x1c0 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-executor387/8017:
 #0: ffff8880a3558d00 (&rp->fetch_lock){+.+.}, at: mon_bin_fetch+0x34/0x300 drivers/usb/mon/mon_bin.c:909

stack backtrace:
CPU: 0 PID: 8017 Comm: syz-executor387 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+0x1d8/0x2f8 lib/dump_stack.c:113
 print_circular_bug+0xc2d/0xe60 kernel/locking/lockdep.c:1685
 check_noncircular+0x206/0x3a0 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+0x161e/0x7bc0 kernel/locking/lockdep.c:2971
 __lock_acquire+0xc75/0x1be0 kernel/locking/lockdep.c:3955
 lock_acquire+0x158/0x250 kernel/locking/lockdep.c:4487
 __might_fault+0xf5/0x160 mm/memory.c:4450
 mon_bin_fetch+0x193/0x300 drivers/usb/mon/mon_bin.c:928
 mon_bin_ioctl+0x7f6/0xc40 drivers/usb/mon/mon_bin.c:1091
 do_vfs_ioctl+0x744/0x1730 fs/ioctl.c:46
 ksys_ioctl fs/ioctl.c:713 [inline]
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0xe3/0x120 fs/ioctl.c:718
 do_syscall_64+0xf7/0x1c0 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:00007fe800c05ce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000006dbc38 RCX: 000000000044a849
RDX: 0000000020000140 RSI: 00000000c0109207 RDI: 0000000000000003
RBP: 00000000006dbc30 R08: 00007fe800c06700 R09: 0000000000000000
R10: 00007fe800c06700 R11: 0000000000000246 R12: 00000000006dbc3c
R13: 00007ffc023fff8f R14: 00007fe800c069c0 R15: 0000000000000001