[moderation] [fs?] WARNING in filename_symlinkat

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 72c395024dac Merge tag 'docs-7.0' of git://git.kernel.org/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=133b3402580000
kernel config: https://syzkaller.appspot.com/x/.config?x=325342ed398e374
dashboard link: https://syzkaller.appspot.com/bug?extid=5244f683c8b443a1fef6
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-72c39502.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7241cf391a0d/vmlinux-72c39502.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e58e169a94cc/bzImage-72c39502.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5244f6...@syzkaller.appspotmail.com

------------[ cut here ]------------
DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)): count = 0x0, magic = 0xffff888047ebd058, owner = 0x0, curr 0xffff888000a10000, list empty
WARNING: kernel/locking/rwsem.c:1381 at __up_write kernel/locking/rwsem.c:1380 [inline], CPU#0: syz.0.0/5325
WARNING: kernel/locking/rwsem.c:1381 at up_write+0x2d6/0x410 kernel/locking/rwsem.c:1643, CPU#0: syz.0.0/5325
Modules linked in:
CPU: 0 UID: 0 PID: 5325 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 80 e6 cc 8b 4c 0f 44 d0 48 8b 7c 24 08 48 c7 c6 e0 e8 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 1a f5 02 03 e9 67 fd ff ff 48 c7 c1
RSP: 0018:ffffc9000e917d80 EFLAGS: 00010246
RAX: ffffffff8bcce660 RBX: ffff888047ebd058 RCX: ffff888047ebd058
RDX: 0000000000000000 RSI: ffffffff8bcce8e0 RDI: ffffffff90130e90
RBP: ffff888047ebd0b0 R08: 0000000000000000 R09: ffff888000a10000
R10: ffffffff8bcce660 R11: ffffed1008fd7a0d R12: 0000000000000000
R13: dffffc0000000000 R14: ffff888047ebd058 R15: 1ffff11008fd7a0c
FS: 00007f8af32526c0(0000) GS:ffff88808cacc000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8af3251ff8 CR3: 0000000044a60000 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_symlinkat+0x222/0x410 fs/namei.c:5642
__do_sys_symlink fs/namei.c:5667 [inline]
__se_sys_symlink+0x4d/0x2b0 fs/namei.c:5663
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8af239bf79
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:00007f8af3252028 EFLAGS: 00000246 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 00007f8af2616180 RCX: 00007f8af239bf79
RDX: 0000000000000000 RSI: 00002000000004c0 RDI: 0000200000000380
RBP: 00007f8af24327e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8af2616218 R14: 00007f8af2616180 R15: 00007ffdd3fcc048
</TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
0: 49 c7 c2 80 e6 cc 8b mov $0xffffffff8bcce680,%r10
7: 4c 0f 44 d0 cmove %rax,%r10
b: 48 8b 7c 24 08 mov 0x8(%rsp),%rdi
10: 48 c7 c6 e0 e8 cc 8b mov $0xffffffff8bcce8e0,%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 1a f5 02 03 call 0x302f550
36: e9 67 fd ff ff jmp 0xfffffda2
3b: 48 rex.W
3c: c7 .byte 0xc7
3d: c1 .byte 0xc1


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