Re: [syzbot] [gfs2?] WARNING in chown_common

[syzbot <syzbot+04c2672c56fbb9401640@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
BUG: About to unlock rwsem we don't own!

After security_path_chown: owner=ffff888033982480
After notify_change: owner=0, error=0
BUG: About to unlock rwsem we don't own!
  inode=ffff8880112b4f80
  i_rwsem.owner=0
  current=ffff888033982480
  delegated_inode=0000000000000000
CPU: 0 UID: 0 PID: 5838 Comm: syz.0.17 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
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 chown_common+0x659/0x700 fs/open.c:803
 do_fchownat+0x161/0x270 fs/open.c:834
 __do_sys_fchownat fs/open.c:849 [inline]
 __se_sys_fchownat fs/open.c:846 [inline]
 __x64_sys_fchownat+0xb5/0xd0 fs/open.c:846
 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: 0033:0x7fd235d8efc9
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:00007fd236c11038 EFLAGS: 00000246 ORIG_RAX: 0000000000000104
RAX: ffffffffffffffda RBX: 00007fd235fe6090 RCX: 00007fd235d8efc9
RDX: 0000000000000000 RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007fd235e11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd235fe6128 R14: 00007fd235fe6090 R15: 00007ffe7f7950f8
 </TASK>
------------[ cut here ]------------
DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)): count = 0x0, magic = 0xffff8880112b5058, owner = 0x0, curr 0xffff888033982480, list empty
WARNING: CPU: 0 PID: 5838 at kernel/locking/rwsem.c:1381 __up_write kernel/locking/rwsem.c:1380 [inline]
WARNING: CPU: 0 PID: 5838 at kernel/locking/rwsem.c:1381 up_write+0x3a2/0x420 kernel/locking/rwsem.c:1643
Modules linked in:
CPU: 0 UID: 0 PID: 5838 Comm: syz.0.17 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 34 7d 8f 80 e1 07 80 c1 03
RSP: 0018:ffffc90002a3fbf0 EFLAGS: 00010296
RAX: 9a6f5dfb05cd2e00 RBX: ffff8880112b5058 RCX: ffff888033982480
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: dffffc0000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1bba684 R12: 0000000000000000
R13: ffff8880112b50b0 R14: ffff8880112b5058 R15: 1ffff11002256a0c
FS:  00007fd236c116c0(0000) GS:ffff88808d730000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007faf3f3f7f50 CR3: 0000000059dc8000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 inode_unlock include/linux/fs.h:990 [inline]
 chown_common+0x4e3/0x700 fs/open.c:805
 do_fchownat+0x161/0x270 fs/open.c:834
 __do_sys_fchownat fs/open.c:849 [inline]
 __se_sys_fchownat fs/open.c:846 [inline]
 __x64_sys_fchownat+0xb5/0xd0 fs/open.c:846
 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: 0033:0x7fd235d8efc9
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:00007fd236c11038 EFLAGS: 00000246 ORIG_RAX: 0000000000000104
RAX: ffffffffffffffda RBX: 00007fd235fe6090 RCX: 00007fd235d8efc9
RDX: 0000000000000000 RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007fd235e11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd235fe6128 R14: 00007fd235fe6090 R15: 00007ffe7f7950f8
 </TASK>


Tested on:

commit:         439fc29d Merge tag 'drm-fixes-2025-11-09' of https://g..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=168e517c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=929790bc044e87d7
dashboard link: https://syzkaller.appspot.com/bug?extid=04c2672c56fbb9401640
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1126517c580000