[moderation] [fs?] WARNING in unlock_mount (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a62b7a37e6fc Add linux-next specific files for 20250711
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17d750f0580000
kernel config: https://syzkaller.appspot.com/x/.config?x=bb4e3ec360fcbd0f
dashboard link: https://syzkaller.appspot.com/bug?extid=0bc701da7fdb42731cdd
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
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: https://storage.googleapis.com/syzbot-assets/7965e5d0fd00/disk-a62b7a37.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d3f74e66ef93/vmlinux-a62b7a37.xz
kernel image: https://storage.googleapis.com/syzbot-assets/90b196a2a6e8/bzImage-a62b7a37.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0bc701...@syzkaller.appspotmail.com

DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)): count = 0x0, magic = 0xffff88806786ebd8, owner = 0x0, curr 0xffff8880698f9e00, list empty
WARNING: kernel/locking/rwsem.c:1383 at __up_write kernel/locking/rwsem.c:1382 [inline], CPU#1: syz.4.2052/17445
WARNING: kernel/locking/rwsem.c:1383 at up_write+0x3a2/0x420 kernel/locking/rwsem.c:1645, CPU#1: syz.4.2052/17445
Modules linked in:
CPU: 1 UID: 0 PID: 17445 Comm: syz.4.2052 Not tainted 6.16.0-rc5-next-20250711-syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__up_write kernel/locking/rwsem.c:1382 [inline]
RIP: 0010:up_write+0x3a2/0x420 kernel/locking/rwsem.c:1645
Code: d0 48 c7 c7 00 ef 8a 8b 48 c7 c6 20 f1 8a 8b 48 8b 14 24 4c 89 f1 4d 89 e0 4c 8b 4c 24 08 41 52 e8 13 43 e6 ff 48 83 c4 08 90 <0f> 0b 90 90 e9 6d fd ff ff 48 c7 c1 74 ec a3 8f 80 e1 07 80 c1 03
RSP: 0018:ffffc90003b6fc68 EFLAGS: 00010282
RAX: ed36858078f48500 RBX: ffff88806786ebd8 RCX: 0000000000080000
RDX: ffffc9000f5b3000 RSI: 000000000000661a RDI: 000000000000661b
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bfa4d8 R12: 0000000000000000
R13: ffff88806786ec30 R14: ffff88806786ebd8 R15: 1ffff1100cf0dd7c
FS: 00007fa008f9e6c0(0000) GS:ffff888125cc6000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2f94383000 CR3: 0000000078056000 CR4: 00000000003526f0
Call Trace:
<TASK>
inode_unlock include/linux/fs.h:879 [inline]
unlock_mount+0x81/0x360 fs/namespace.c:2846
do_loopback+0x3b5/0x430 fs/namespace.c:3044
do_mount fs/namespace.c:4133 [inline]
__do_sys_mount fs/namespace.c:4344 [inline]
__se_sys_mount+0x317/0x410 fs/namespace.c:4321
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa00818e929
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:00007fa008f9e038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fa0083b6160 RCX: 00007fa00818e929
RDX: 0000000000000000 RSI: 0000200000000200 RDI: 0000200000000c40
RBP: 00007fa008210b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000002901090 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007fa0083b6160 R15: 00007fff95cb9588
</TASK>


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.