[syzbot] [bcachefs?] kernel BUG in bch2_fs_btree_write_buffer_exit

syzbot
2024-09-28T02:13:29Z

Hello,

syzbot found the following issue on:

HEAD commit: 5f5673607153 Merge branch 'for-next/core' into for-kernelci
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=11ef8507980000
kernel config: https://syzkaller.appspot.com/x/.config?x=dedbcb1ff4387972
dashboard link: https://syzkaller.appspot.com/bug?extid=e4b5080f1e963225063e
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/40172aed5414/disk-5f567360.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/58372f305e9d/vmlinux-5f567360.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d2aae6fa798f/Image-5f567360.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e4b5080f1e963225063e@syzkaller.appspotmail.com

------------[ cut here ]------------
kernel BUG at fs/bcachefs/btree_write_buffer.c:801!
Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 UID: 0 PID: 6419 Comm: syz-executor Not tainted 6.11.0-rc7-syzkaller-g5f5673607153 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : bch2_fs_btree_write_buffer_exit+0x1dc/0x1e0 fs/bcachefs/btree_write_buffer.c:800
lr : bch2_fs_btree_write_buffer_exit+0x1dc/0x1e0 fs/bcachefs/btree_write_buffer.c:800
sp : ffff8000a3217a80
x29: ffff8000a3217a80 x28: 1fffe0001e5b0010 x27: 1fffe0001e5b000d
x26: dfff800000000000 x25: ffff0000f2d80000 x24: dfff800000000000
x23: ffff0000f2dcb174 x22: 00000000000fffff x21: 00000000000ffffe
x20: ffff0000f2d80000 x19: ffff0000f2d845a0 x18: 1fffe000366d79ee
x17: ffff80008f56d000 x16: ffff80008b274880 x15: 0000000000000001
x14: 1fffe0001e5b962e x13: 0000000000000000 x12: 0000000000000000
x11: ffff60001e5b962f x10: 0000000000ff0100 x9 : 0000000000000000
x8 : ffff0000ea698000 x7 : 0000000000000000 x6 : 000000000000003f
x5 : 0000000000000040 x4 : 0000000000000000 x3 : ffff800082a3a0cc
x2 : 0000000000000000 x1 : 00000000000ffffe x0 : 00000000000fffff
Call trace:
bch2_fs_btree_write_buffer_exit+0x1dc/0x1e0 fs/bcachefs/btree_write_buffer.c:800
__bch2_fs_free fs/bcachefs/super.c:564 [inline]
bch2_fs_release+0x2d4/0x720 fs/bcachefs/super.c:608
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x2a8/0x41c lib/kobject.c:737
bch2_fs_free+0x2c4/0x334 fs/bcachefs/super.c:672
bch2_kill_sb+0x48/0x58 fs/bcachefs/fs.c:2055
deactivate_locked_super+0xc4/0x12c fs/super.c:473
deactivate_super+0xe0/0x100 fs/super.c:506
cleanup_mnt+0x34c/0x3dc fs/namespace.c:1373
__cleanup_mnt+0x20/0x30 fs/namespace.c:1380
task_work_run+0x230/0x2e0 kernel/task_work.c:228
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
do_notify_resume+0x178/0x1f4 arch/arm64/kernel/entry-common.c:151
exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline]
el0_svc+0xac/0x168 arch/arm64/kernel/entry-common.c:713
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
Code: d65f03c0 9774c432 17ffffc0 9774c430 (d4210000)
---[ end trace 0000000000000000 ]---

---
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