[syzbot] [bcachefs?] kernel BUG in bch2_fs_btree_cache_exit

[syzbot] [bcachefs?] kernel BUG in bch2_fs_btree_cache_exit

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    c964ced77262 Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=17f10240580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=164d2822debd8b0d
dashboard link: https://syzkaller.appspot.com/bug?extid=4deac4f47f33e16f82b7
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10090240580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=113be830580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fb46e19c1a07/disk-c964ced7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/521abb58e739/vmlinux-c964ced7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ea079e4ac77f/bzImage-c964ced7.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/f2414169f0cc/mount_0.gz

The issue was bisected to:

commit bf4baaa087e2be0279991f1dbf9acaa7a4c9148c
Author: Kent Overstreet <kent.overstreet@linux.dev>
Date:   Sat Oct 5 21:37:02 2024 +0000

    bcachefs: Fix lockdep splat in bch2_accounting_read

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=166b0487980000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=156b0487980000
console output: https://syzkaller.appspot.com/x/log.txt?x=116b0487980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4deac4f47f33e16f82b7@syzkaller.appspotmail.com
Fixes: bf4baaa087e2 ("bcachefs: Fix lockdep splat in bch2_accounting_read")

------------[ cut here ]------------
kernel BUG at fs/bcachefs/btree_cache.c:594!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 0 UID: 0 PID: 5223 Comm: syz-executor386 Not tainted 6.12.0-rc3-syzkaller-00087-gc964ced77262 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:bch2_fs_btree_cache_exit+0x1124/0x1130 fs/bcachefs/btree_cache.c:593
Code: fd 90 0f 0b e8 dd 66 84 fd 90 0f 0b e8 d5 66 84 fd 90 0f 0b e8 cd 66 84 fd 90 0f 0b e8 c5 66 84 fd 90 0f 0b e8 bd 66 84 fd 90 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90003b37b20 EFLAGS: 00010293
RAX: ffffffff84108043 RBX: 0000000000000002 RCX: ffff888024728000
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
RBP: 1ffff11005c49016 R08: ffffffff841076e7 R09: 1ffff1100bc503b6
R10: dffffc0000000000 R11: ffffed100bc503b7 R12: ffff88805e281c78
R13: ffff88805e280000 R14: 0000000000000000 R15: dffffc0000000000
FS:  000055558a7d6380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc6ecbff000 CR3: 0000000074002000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __bch2_fs_free fs/bcachefs/super.c:556 [inline]
 bch2_fs_release+0x20e/0x7d0 fs/bcachefs/super.c:610
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x22f/0x480 lib/kobject.c:737
 deactivate_locked_super+0xc4/0x130 fs/super.c:473
 cleanup_mnt+0x41f/0x4b0 fs/namespace.c:1373
 task_work_run+0x24f/0x310 kernel/task_work.c:228
 ptrace_notify+0x2d2/0x380 kernel/signal.c:2403
 ptrace_report_syscall include/linux/ptrace.h:415 [inline]
 ptrace_report_syscall_exit include/linux/ptrace.h:477 [inline]
 syscall_exit_work+0xc6/0x190 kernel/entry/common.c:173
 syscall_exit_to_user_mode_prepare kernel/entry/common.c:200 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:205 [inline]
 syscall_exit_to_user_mode+0x279/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc6f42275f7
Code: 07 00 48 83 c4 08 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffdf9e61628 EFLAGS: 00000206 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007fc6f42275f7
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffdf9e616e0
RBP: 00007ffdf9e616e0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000206 R12: 00007ffdf9e62750
R13: 000055558a7d76c0 R14: 431bde82d7b634db R15: 00007ffdf9e62770
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bch2_fs_btree_cache_exit+0x1124/0x1130 fs/bcachefs/btree_cache.c:593
Code: fd 90 0f 0b e8 dd 66 84 fd 90 0f 0b e8 d5 66 84 fd 90 0f 0b e8 cd 66 84 fd 90 0f 0b e8 c5 66 84 fd 90 0f 0b e8 bd 66 84 fd 90 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc90003b37b20 EFLAGS: 00010293
RAX: ffffffff84108043 RBX: 0000000000000002 RCX: ffff888024728000
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000
RBP: 1ffff11005c49016 R08: ffffffff841076e7 R09: 1ffff1100bc503b6
R10: dffffc0000000000 R11: ffffed100bc503b7 R12: ffff88805e281c78
R13: ffff88805e280000 R14: 0000000000000000 R15: dffffc0000000000
FS:  000055558a7d6380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc6ecbff000 CR3: 0000000074002000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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***

Subject: 
Author: kent.overstreet@linux.dev

#syz fix: bcachefs: bch2_btree_write_buffer_flush_going_ro()