[moderation] [fs?] WARNING in chmod_common (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 439fc29dfd3b Merge tag 'drm-fixes-2025-11-09' of https://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16d3ea92580000
kernel config: https://syzkaller.appspot.com/x/.config?x=929790bc044e87d7
dashboard link: https://syzkaller.appspot.com/bug?extid=6f8f7254783f5b261e86
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
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-439fc29d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f99d22d33b4f/vmlinux-439fc29d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/df30b75ce193/bzImage-439fc29d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6f8f72...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 32768
gfs2: fsid=syz:syz: Trying to join cluster "lock_nolock", "syz:syz"
gfs2: fsid=syz:syz: Now mounting FS (format 1801)...
gfs2: fsid=syz:syz.0: journal 0 mapped with 1 extents in 0ms
gfs2: fsid=syz:syz.0: first mount done, others may mount
------------[ cut here ]------------
DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)): count = 0x0, magic = 0xffff888043095058, owner = 0x0, curr 0xffff8880317cc900, list empty
WARNING: CPU: 0 PID: 5326 at kernel/locking/rwsem.c:1381 __up_write kernel/locking/rwsem.c:1380 [inline]
WARNING: CPU: 0 PID: 5326 at kernel/locking/rwsem.c:1381 up_write+0x3a2/0x420 kernel/locking/rwsem.c:1643
Modules linked in:
CPU: 0 UID: 0 PID: 5326 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~bpo12+1 04/01/2014
RIP: 0010:__up_write kernel/locking/rwsem.c:1380 [inline]
RIP: 0010:up_write+0x3a2/0x420 kernel/locking/rwsem.c:1643
Code: d0 48 c7 c7 20 ff 6a 8b 48 c7 c6 40 01 6b 8b 48 8b 14 24 4c 89 f1 4d 89 e0 4c 8b 4c 24 08 41 52 e8 c3 35 e6 ff 48 83 c4 08 90 <0f> 0b 90 90 e9 6d fd ff ff 48 c7 c1 94 33 7d 8f 80 e1 07 80 c1 03
RSP: 0018:ffffc9000d437c50 EFLAGS: 00010296
RAX: 5fc7658723caf100 RBX: ffff888043095058 RCX: ffff8880317cc900
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bba684 R12: 0000000000000000
R13: ffff8880430950b0 R14: ffff888043095058 R15: 1ffff11008612a0c
FS: 00007f29dd8ff6c0(0000) GS:ffff88808d730000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f29dd8ddfc8 CR3: 00000000113cb000 CR4: 0000000000352ef0
Call Trace:
<TASK>
inode_unlock include/linux/fs.h:990 [inline]
chmod_common+0x253/0x400 fs/open.c:653
do_fchmodat+0x12d/0x200 fs/open.c:697
__do_sys_fchmodat fs/open.c:716 [inline]
__se_sys_fchmodat fs/open.c:713 [inline]
__x64_sys_fchmodat+0x7d/0x90 fs/open.c:713
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f29dc98f6c9
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:00007f29dd8ff038 EFLAGS: 00000246 ORIG_RAX: 000000000000010c
RAX: ffffffffffffffda RBX: 00007f29dcbe5fa0 RCX: 00007f29dc98f6c9
RDX: 0000000000000008 RSI: 0000200000000000 RDI: 0000000000000004
RBP: 00007f29dca11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f29dcbe6038 R14: 00007f29dcbe5fa0 R15: 00007ffd5a29cc38
</TASK>


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