[moderation] [fs?] WARNING in filename_mknodat

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 770aaedb461a Merge tag 'bootconfig-v7.0' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13d8c15a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=bdcbd6339981e22b
dashboard link: https://syzkaller.appspot.com/bug?extid=9760e4d233c54d8a2151
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-770aaedb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/98e22e2e70c4/vmlinux-770aaedb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ff29a1b594c6/bzImage-770aaedb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9760e4...@syzkaller.appspotmail.com

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DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)): count = 0x0, magic = 0xffff8880558fc9b8, owner = 0x0, curr 0xffff88801fb20000, list empty
WARNING: kernel/locking/rwsem.c:1381 at __up_write kernel/locking/rwsem.c:1380 [inline], CPU#0: syz.0.0/5315
WARNING: kernel/locking/rwsem.c:1381 at up_write+0x2d6/0x410 kernel/locking/rwsem.c:1643, CPU#0: syz.0.0/5315
Modules linked in:
CPU: 0 UID: 0 PID: 5315 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 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 c0 eb cc 8b 4c 0f 44 d0 48 8b 7c 24 08 48 c7 c6 20 ee 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 aa 8a 09 03 e9 67 fd ff ff 48 c7 c1
RSP: 0018:ffffc9000f427d80 EFLAGS: 00010246
RAX: ffffffff8bcceba0 RBX: ffff8880558fc9b8 RCX: ffff8880558fc9b8
RDX: 0000000000000000 RSI: ffffffff8bccee20 RDI: ffffffff90149d50
RBP: ffff8880558fca10 R08: 0000000000000000 R09: ffff88801fb20000
R10: ffffffff8bcceba0 R11: ffffed100ab1f939 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff8880558fc9b8 R15: 1ffff1100ab1f938
FS: 00007fc1f7c5e6c0(0000) GS:ffff88808ca67000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001600 CR3: 0000000011fc3000 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_mknodat+0x458/0x660 fs/namei.c:5156
__do_sys_mknodat fs/namei.c:5173 [inline]
__se_sys_mknodat+0x3b/0x150 fs/namei.c:5169
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: 0033:0x7fc1f6d9bf79
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:00007fc1f7c5e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000103
RAX: ffffffffffffffda RBX: 00007fc1f7016090 RCX: 00007fc1f6d9bf79
RDX: 0000000000006000 RSI: 0000200000001600 RDI: 0000000000000009
RBP: 00007fc1f6e327e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000700 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc1f7016128 R14: 00007fc1f7016090 R15: 00007ffc81fc1a48
</TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
0: 49 c7 c2 c0 eb cc 8b mov $0xffffffff8bccebc0,%r10
7: 4c 0f 44 d0 cmove %rax,%r10
b: 48 8b 7c 24 08 mov 0x8(%rsp),%rdi
10: 48 c7 c6 20 ee cc 8b mov $0xffffffff8bccee20,%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 aa 8a 09 03 call 0x3098ae0
36: e9 67 fd ff ff jmp 0xfffffda2
3b: 48 rex.W
3c: c7 .byte 0xc7
3d: c1 .byte 0xc1


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