[syzbot] [block?] WARNING in bioset_exit (2)

[syzbot <syzbot+1bfac8c74f4f587bf9c7@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    1343433ed389 Add linux-next specific files for 20250630
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=100c93d4580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=c1ce97baf6bd6397
dashboard link: https://syzkaller.appspot.com/bug?extid=1bfac8c74f4f587bf9c7
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c3387c64e9ec/disk-1343433e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/abf15e85d8dd/vmlinux-1343433e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/081c344403bc/bzImage-1343433e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1bfac8c74f4f587bf9c7@syzkaller.appspotmail.com

BUG bio-240 (Not tainted): Objects remaining on __kmem_cache_shutdown()
-----------------------------------------------------------------------------
Object 0xffff88806ae61000 @offset=0
Slab 0xffffea0001ab9840 objects=12 used=1 fp=0xffff88806ae61140 flags=0xfff00000000200(workingset|node=0|zone=1|lastcpupid=0x7ff)
Disabling lock debugging due to kernel taint
------------[ cut here ]------------
WARNING: mm/slub.c:1171 at __slab_err+0x15/0x20 mm/slub.c:1171, CPU#0: syz.4.178/6655
Modules linked in:
CPU: 0 UID: 0 PID: 6655 Comm: syz.4.178 Tainted: G    B               6.16.0-rc4-next-20250630-syzkaller #0 PREEMPT(full) 
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__slab_err+0x15/0x20 mm/slub.c:1171
Code: 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 e8 bb ff ff ff bf 05 00 00 00 be 01 00 00 00 e8 1c 6c 5b 00 90 <0f> 0b 90 e9 d3 77 4a 0a cc 66 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000baa7868 EFLAGS: 00010046
RAX: ffffffff81836dfa RBX: ffff888026c3d000 RCX: 0000000000080000
RDX: ffffc9000ce29000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: 0000000000000000 R08: ffffffff92a69fc7 R09: 1ffffffff254d3f8
R10: dffffc0000000000 R11: fffffbfff254d3f9 R12: ffff888077b75648
R13: ffffea0001ab9840 R14: ffff888077b75648 R15: ffff888077b75600
FS:  00007fe6701f66c0(0000) GS:ffff888125c1d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9212ee56c0 CR3: 000000007e528000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 free_partial mm/slub.c:5903 [inline]
 __kmem_cache_shutdown+0xd4/0x250 mm/slub.c:5934
 kmem_cache_destroy+0x76/0x160 mm/slab_common.c:523
 bio_put_slab block/bio.c:155 [inline]
 bioset_exit+0x583/0x690 block/bio.c:1764
 __bch2_fs_free fs/bcachefs/super.c:609 [inline]
 bch2_fs_release+0x25c/0x830 fs/bcachefs/super.c:667
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x22b/0x480 lib/kobject.c:737
 bch2_fs_get_tree+0xb39/0x14f0 fs/bcachefs/fs.c:2605
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1804
 do_new_mount+0x24a/0xa40 fs/namespace.c:3902
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4427
 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: 0033:0x7fe6723900ca
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007fe6701f5e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fe6701f5ef0 RCX: 00007fe6723900ca
RDX: 0000200000000140 RSI: 0000200000000100 RDI: 00007fe6701f5eb0
RBP: 0000200000000140 R08: 00007fe6701f5ef0 R09: 0000000002800000
R10: 0000000002800000 R11: 0000000000000246 R12: 0000200000000100
R13: 00007fe6701f5eb0 R14: 0000000000005a7a R15: 0000200000000300
 </TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup