Re: [syzbot] [gfs2?] WARNING in filename_mkdirat

syzbot has found a reproducer for the following issue on:

HEAD commit:    956b9cbd7f15 Merge tag 'kbuild-fixes-7.0-1' of git://git.k..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14c81ffa580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=65722f41f7edc17e
dashboard link: https://syzkaller.appspot.com/bug?extid=0ea5108a1f5fb4fcc2d8
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1622495a580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1600e95a580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-956b9cbd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f0b3757a15ed/vmlinux-956b9cbd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c564e8613b4e/bzImage-956b9cbd.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/2e0152c5e6ec/mount_1.gz
  fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=141eb15a580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]

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DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)): count = 0x0, magic = 0xffff88804665f818, owner = 0x0, curr 0xffff888035922480, list empty
WARNING: kernel/locking/rwsem.c:1381 at __up_write kernel/locking/rwsem.c:1380 [inline], CPU#0: syz.0.30/5574
WARNING: kernel/locking/rwsem.c:1381 at up_write+0x2d6/0x410 kernel/locking/rwsem.c:1643, CPU#0: syz.0.30/5574
Modules linked in:
CPU: 0 UID: 0 PID: 5574 Comm: syz.0.30 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__up_write kernel/locking/rwsem.c:1380 [inline]
RIP: 0010:up_write+0x388/0x410 kernel/locking/rwsem.c:1643
Code: cc 8b 49 c7 c2 80 eb cc 8b 4c 0f 44 d0 48 8b 7c 24 08 48 c7 c6 e0 ed cc 8b 48 8b 14 24 4c 89 f1 4d 89 e0 4c 8b 4c 24 10 41 52 <67> 48 0f b9 3a 48 83 c4 08 e8 0a 0c 0b 03 e9 67 fd ff ff 48 c7 c1
RSP: 0018:ffffc90006407d80 EFLAGS: 00010246
RAX: ffffffff8bcceb60 RBX: ffff88804665f818 RCX: ffff88804665f818
RDX: 0000000000000000 RSI: ffffffff8bccede0 RDI: ffffffff9014e210
RBP: ffff88804665f870 R08: 0000000000000000 R09: ffff888035922480
R10: ffffffff8bcceb60 R11: ffffed1008ccbf05 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff88804665f818 R15: 1ffff11008ccbf04
FS:  00007fe0f01196c0(0000) GS:ffff88808ca5b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe0f0118ff8 CR3: 000000004158f000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 inode_unlock include/linux/fs.h:1038 [inline]
 end_dirop fs/namei.c:2947 [inline]
 end_creating include/linux/namei.h:126 [inline]
 end_creating_path fs/namei.c:4962 [inline]
 filename_mkdirat+0x305/0x510 fs/namei.c:5271
 __do_sys_mkdir fs/namei.c:5293 [inline]
 __se_sys_mkdir+0x34/0x150 fs/namei.c:5290
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe0ef19c629
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe0f0119028 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007fe0ef416090 RCX: 00007fe0ef19c629
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000040
RBP: 00007fe0ef232b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe0ef416128 R14: 00007fe0ef416090 R15: 00007ffff03e4318
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	49 c7 c2 80 eb cc 8b 	mov    $0xffffffff8bcceb80,%r10
   7:	4c 0f 44 d0          	cmove  %rax,%r10
   b:	48 8b 7c 24 08       	mov    0x8(%rsp),%rdi
  10:	48 c7 c6 e0 ed cc 8b 	mov    $0xffffffff8bccede0,%rsi
  17:	48 8b 14 24          	mov    (%rsp),%rdx
  1b:	4c 89 f1             	mov    %r14,%rcx
  1e:	4d 89 e0             	mov    %r12,%r8
  21:	4c 8b 4c 24 10       	mov    0x10(%rsp),%r9
  26:	41 52                	push   %r10
* 28:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2d:	48 83 c4 08          	add    $0x8,%rsp
  31:	e8 0a 0c 0b 03       	call   0x30b0c40
  36:	e9 67 fd ff ff       	jmp    0xfffffda2
  3b:	48                   	rex.W
  3c:	c7                   	.byte 0xc7
  3d:	c1                   	.byte 0xc1


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