------------[ cut here ]------------
DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem)): count = 0x0, magic = 0xffff88804854d058, owner = 0x0, curr 0xffff88801c7b0000, list empty
WARNING: kernel/locking/rwsem.c:1354 at __up_read+0x4f9/0x670 kernel/locking/rwsem.c:1354, CPU#0: syz.0.0/5411
Modules linked in:
CPU: 0 UID: 0 PID: 5411 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:__up_read+0x5df/0x670 kernel/locking/rwsem.c:1354
Code: 23 6b 8b 49 c7 c2 c0 23 6b 8b 4c 0f 44 d0 48 8b 7c 24 28 48 c7 c6 60 23 6b 8b 4c 89 ea 48 8b 4c 24 20 4d 89 f0 4d 89 f9 41 52 <67> 48 0f b9 3a 48 83 c4 08 e8 93 a2 ee 02 e9 6e fb ff ff 48 c7 c1
RSP: 0018:ffffc9000ef17a18 EFLAGS: 00010246
RAX: ffffffff8b6b23a0 RBX: ffff88804854d058 RCX: ffff88804854d058
RDX: 0000000000000000 RSI: ffffffff8b6b2360 RDI: ffffffff8f858520
RBP: ffffc9000ef17ae8 R08: 0000000000000000 R09: ffff88801c7b0000
R10: ffffffff8b6b23a0 R11: ffffed10090a9a0d R12: ffff88804854d0b0
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88801c7b0000
FS:  00007f382e0af6c0(0000) GS:ffff88808d414000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000020c0 CR3: 0000000011e3d000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 inode_unlock_shared include/linux/fs.h:1052 [inline]
 lookup_slow+0x5e/0x70 fs/namei.c:1876
 walk_component fs/namei.c:2221 [inline]
 lookup_last fs/namei.c:2722 [inline]
 path_lookupat+0x3f5/0x8c0 fs/namei.c:2746
 filename_lookup+0x212/0x570 fs/namei.c:2775
 user_path_at+0x3a/0x60 fs/namei.c:3567
 do_mount fs/namespace.c:4032 [inline]
 __do_sys_mount fs/namespace.c:4224 [inline]
 __se_sys_mount+0x2d4/0x410 fs/namespace.c:4201
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f382d18f7c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f382e0af038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f382d3e6180 RCX: 00007f382d18f7c9
RDX: 0000200000000000 RSI: 00002000000020c0 RDI: 0000000000000000
RBP: 00007f382d213f91 R08: 0000200000000040 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f382d3e6218 R14: 00007f382d3e6180 R15: 00007ffe4ef60dd8
 </TASK>
----------------
Code disassembly (best guess):
   0:	23 6b 8b             	and    -0x75(%rbx),%ebp
   3:	49 c7 c2 c0 23 6b 8b 	mov    $0xffffffff8b6b23c0,%r10
   a:	4c 0f 44 d0          	cmove  %rax,%r10
   e:	48 8b 7c 24 28       	mov    0x28(%rsp),%rdi
  13:	48 c7 c6 60 23 6b 8b 	mov    $0xffffffff8b6b2360,%rsi
  1a:	4c 89 ea             	mov    %r13,%rdx
  1d:	48 8b 4c 24 20       	mov    0x20(%rsp),%rcx
  22:	4d 89 f0             	mov    %r14,%r8
  25:	4d 89 f9             	mov    %r15,%r9
  28:	41 52                	push   %r10
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	48 83 c4 08          	add    $0x8,%rsp
  33:	e8 93 a2 ee 02       	call   0x2eea2cb
  38:	e9 6e fb ff ff       	jmp    0xfffffbab
  3d:	48                   	rex.W
  3e:	c7                   	.byte 0xc7
  3f:	c1                   	.byte 0xc1