[v6.6] WARNING in lookup_slow

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5fa4793a2d2d Linux 6.6.119
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=116a3e9a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=691a6769a86ac817
dashboard link: https://syzkaller.appspot.com/bug?extid=46b2450852b8be2d7e30
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/63699875f1dd/disk-5fa4793a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8506652fcb6f/vmlinux-5fa4793a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1b30ceed1710/bzImage-5fa4793a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+46b245...@syzkaller.appspotmail.com

DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem)): count = 0x0, magic = 0xffff8880575c79e0, owner = 0x0, curr 0xffff88802cc1bc00, list empty
WARNING: CPU: 1 PID: 13081 at kernel/locking/rwsem.c:1343 __up_read+0x5e5/0x670 kernel/locking/rwsem.c:1343
Modules linked in:
CPU: 1 PID: 13081 Comm: syz.0.943 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__up_read+0x5e5/0x670 kernel/locking/rwsem.c:1343
Code: 0f 44 d0 48 c7 c7 80 b0 aa 8a 48 c7 c6 20 b1 aa 8a 4c 89 ea 48 8b 4c 24 08 4d 89 e0 4d 89 f1 41 52 e8 7f a4 e9 ff 48 83 c4 08 <0f> 0b e9 85 fb ff ff 48 c7 c1 f0 55 4a 8e 80 e1 07 80 c1 03 38 c1
RSP: 0018:ffffc90004897a60 EFLAGS: 00010296
RAX: 2798dd4473166a00 RBX: ffff8880575c79e0 RCX: 0000000000080000
RDX: ffffc90014bb3000 RSI: 000000000000e7b7 RDI: 000000000000e7b8
RBP: ffffc90004897b20 R08: ffffc90004897667 R09: 1ffff92000912ecc
R10: dffffc0000000000 R11: fffff52000912ecd R12: 0000000000000000
R13: 0000000000000000 R14: ffff88802cc1bc00 R15: ffff8880575c7a38
FS: 00007fcb1e3d56c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fefc41d4f98 CR3: 000000007b0e6000 CR4: 00000000003506e0
Call Trace:
<TASK>
inode_unlock_shared include/linux/fs.h:819 [inline]
lookup_slow+0x5e/0x70 fs/namei.c:1720
walk_component+0x2be/0x3f0 fs/namei.c:2010
lookup_last fs/namei.c:2467 [inline]
path_lookupat+0x169/0x440 fs/namei.c:2491
filename_lookup+0x1f4/0x510 fs/namei.c:2520
user_path_at_empty+0x42/0x60 fs/namei.c:2917
user_path_at include/linux/namei.h:57 [inline]
do_mount fs/namespace.c:3723 [inline]
__do_sys_mount fs/namespace.c:3935 [inline]
__se_sys_mount+0x29b/0x3c0 fs/namespace.c:3912
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fcb2018f749
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:00007fcb1e3d5038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fcb203e6180 RCX: 00007fcb2018f749
RDX: 0000000000000000 RSI: 0000200000000040 RDI: 0000200000000440
RBP: 00007fcb20213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000003ab1019 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcb203e6218 R14: 00007fcb203e6180 R15: 00007fff6e4adcb8
</TASK>


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