Message-ID: <69717cbf.050a0220.706b.001d.GAE@google.com>
Date: Wed, 21 Jan 2026 17:26:23 -0800
From: syzbot <syzbot+bcfb99c4698edf7a1f52@...kaller.appspotmail.com>
To: jack@...e.com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [udf?] WARNING: bad unlock balance in __wait_on_freeing_inode

Hello,

syzbot found the following issue on:

HEAD commit:    46fe65a2c28e Add linux-next specific files for 20260116
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=14928b9a580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=810a09a784e5ae02
dashboard link: https://syzkaller.appspot.com/bug?extid=bcfb99c4698edf7a1f52
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14a593fa580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1180db9a580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2c6f635d5a97/disk-46fe65a2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/565933a63b5e/vmlinux-46fe65a2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/65da6a82868a/bzImage-46fe65a2.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/920e89c61c32/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bcfb99c4698edf7a1f52@...kaller.appspotmail.com

=====================================
WARNING: bad unlock balance detected!
syzkaller #0 Not tainted
-------------------------------------
syz.2.233/6549 is trying to release lock (rcu_read_lock) at:
[<ffffffff8241d114>] rcu_lock_release include/linux/rcupdate.h:322 [inline]
[<ffffffff8241d114>] rcu_read_unlock include/linux/rcupdate.h:881 [inline]
[<ffffffff8241d114>] __wait_on_freeing_inode+0x174/0x2f0 fs/inode.c:2544
but there are no more locks to release!

other info that might help us debug this:
3 locks held by syz.2.233/6549:
 #0: ffff8880574ae420 (sb_writers#12){.+.+}-{0:0}, at: mnt_want_write+0x41/0x90 fs/namespace.c:504
 #1: ffff88805a586150 (&type->i_mutex_dir_key#8){++++}-{4:4}, at: inode_lock include/linux/fs.h:1028 [inline]
 #1: ffff88805a586150 (&type->i_mutex_dir_key#8){++++}-{4:4}, at: open_last_lookups fs/namei.c:4578 [inline]
 #1: ffff88805a586150 (&type->i_mutex_dir_key#8){++++}-{4:4}, at: path_openat+0xb4c/0x3840 fs/namei.c:4825
 #2: ffffffff8de16918 (inode_hash_lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:344 [inline]
 #2: ffffffff8de16918 (inode_hash_lock){+.+.}-{3:3}, at: insert_inode_locked+0xf8/0x4f0 fs/inode.c:1834

stack backtrace:
CPU: 1 UID: 0 PID: 6549 Comm: syz.2.233 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_unlock_imbalance_bug+0xdc/0xf0 kernel/locking/lockdep.c:5298
 __lock_release kernel/locking/lockdep.c:5537 [inline]
 lock_release+0x249/0x3b0 kernel/locking/lockdep.c:5889
 rcu_lock_release include/linux/rcupdate.h:322 [inline]
 rcu_read_unlock include/linux/rcupdate.h:881 [inline]
 __wait_on_freeing_inode+0x183/0x2f0 fs/inode.c:2544
 insert_inode_locked+0x1f5/0x4f0 fs/inode.c:1853
 udf_new_inode+0x9b6/0xd50 fs/udf/ialloc.c:105
 udf_create+0x23/0xf0 fs/udf/namei.c:376
 lookup_open fs/namei.c:4481 [inline]
 open_last_lookups fs/namei.c:4581 [inline]
 path_openat+0x1387/0x3840 fs/namei.c:4825
 do_file_open+0x203/0x440 fs/namei.c:4857
 do_sys_openat2+0x105/0x1e0 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f22bf78f749
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:00007f22c0605038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f22bf9e6090 RCX: 00007f22bf78f749
RDX: 000000000000275a RSI: 0000200000000180 RDI: ffffffffffffff9c
RBP: 00007f22bf813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f22bf9e6128 R14: 00007f22bf9e6090 R15: 00007fffe4523188
 </TASK>
------------[ cut here ]------------
WARNING: kernel/rcu/tree_plugin.h:443 at __rcu_read_unlock+0x7a/0xe0 kernel/rcu/tree_plugin.h:443, CPU#1: syz.2.233/6549
Modules linked in:
CPU: 1 UID: 0 PID: 6549 Comm: syz.2.233 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:__rcu_read_unlock+0x7a/0xe0 kernel/rcu/tree_plugin.h:443
Code: 75 66 41 83 3e 00 75 27 43 0f b6 04 3c 84 c0 75 41 8b 03 3d 00 00 00 40 73 0f 5b 41 5c 41 5d 41 5e 41 5f e9 08 a0 b9 09 cc 90 <0f> 0b 90 eb eb e8 6c 00 00 00 eb d2 89 d9 80 e1 07 80 c1 03 38 c1
RSP: 0000:ffffc9000b98f6b0 EFLAGS: 00010286
RAX: 00000000ffffffff RBX: ffff888075594104 RCX: 0000000080000001
RDX: 0000000000000000 RSI: ffffffff8db8bddd RDI: ffff888075593c80
RBP: ffffc9000b98f7c0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1c04060 R12: 1ffff1100eab2820
R13: 1ffff92001731edc R14: ffffc9000b98f718 R15: dffffc0000000000
FS:  00007f22c06056c0(0000) GS:ffff888125cf9000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f22c0604f98 CR3: 00000000742e2000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 rcu_read_unlock include/linux/rcupdate.h:883 [inline]
 __wait_on_freeing_inode+0x188/0x2f0 fs/inode.c:2544
 insert_inode_locked+0x1f5/0x4f0 fs/inode.c:1853
 udf_new_inode+0x9b6/0xd50 fs/udf/ialloc.c:105
 udf_create+0x23/0xf0 fs/udf/namei.c:376
 lookup_open fs/namei.c:4481 [inline]
 open_last_lookups fs/namei.c:4581 [inline]
 path_openat+0x1387/0x3840 fs/namei.c:4825
 do_file_open+0x203/0x440 fs/namei.c:4857
 do_sys_openat2+0x105/0x1e0 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f22bf78f749
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:00007f22c0605038 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f22bf9e6090 RCX: 00007f22bf78f749
RDX: 000000000000275a RSI: 0000200000000180 RDI: ffffffffffffff9c
RBP: 00007f22bf813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f22bf9e6128 R14: 00007f22bf9e6090 R15: 00007fffe4523188
 </TASK>


---
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