[syzbot] [bcachefs?] kernel BUG in bch2_journal_pin_set_locked

Hello,

syzbot found the following issue on:

HEAD commit:    0e39a731820a Merge tag 'for-6.17-rc1-tag' of git://git.ker..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12c6f5bc580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d67d3af29f50297e
dashboard link: https://syzkaller.appspot.com/bug?extid=014934d9b1d3601f30db
compiler:       Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-0e39a731.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4de62048a1d4/vmlinux-0e39a731.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5ed93317a562/bzImage-0e39a731.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]

bcachefs (loop0): u64s 12 type alloc_v4 0:42:0 len 0 ver 0: 
    gen 0 oldest_gen 0 data_type btree
    journal_seq_nonempty 7
    journal_seq_empty    0
    need_discard         1
    need_inc_gen         1
    dirty_sectors        256
    stripe_sectors       0
    cached_sectors       0
    stripe               0
    stripe_redundancy    0
    io_time[READ]        1
    io_time[WRITE]       1280
    fragmentation     0
    bp_start          7
  
  incorrectly set at freespace:0:42:0 (free 0, genbits 0 should be 0), fixing
------------[ cut here ]------------
kernel BUG at fs/bcachefs/journal_reclaim.h:30!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 1037 Comm: kworker/u4:5 Not tainted 6.17.0-rc1-syzkaller-00014-g0e39a731820a #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
Workqueue: btree_node_rewrite async_btree_node_rewrite_work
RIP: 0010:journal_seq_pin fs/bcachefs/journal_reclaim.h:30 [inline]
RIP: 0010:bch2_journal_pin_set_locked+0x346/0x350 fs/bcachefs/journal_reclaim.c:422
Code: fe ff ff e8 3c 92 72 fd 48 c7 c7 e0 f5 78 8e 4c 89 e6 e8 bd 86 b3 00 e9 54 fe ff ff e8 23 92 72 fd 90 0f 0b e8 1b 92 72 fd 90 <0f> 0b e8 13 92 72 fd 90 0f 0b 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000256f6a0 EFLAGS: 00010293
RAX: ffffffff844d2945 RBX: ffff8880119ce108 RCX: ffff888032e4a440
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000005 R08: 0000000000000005 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520004adecc R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff888054049800
FS:  0000000000000000(0000) GS:ffff88808d211000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000564f7dae2a38 CR3: 0000000051967000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 bch2_journal_pin_copy+0x4c7/0x5b0 fs/bcachefs/journal_reclaim.c:463
 bch2_btree_interior_update_will_free_node+0x478/0xef0 fs/bcachefs/btree_update_interior.c:1092
 bch2_btree_node_rewrite+0x9ac/0x1120 fs/bcachefs/btree_update_interior.c:2275
 bch2_btree_node_rewrite_key+0x273/0x320 fs/bcachefs/btree_update_interior.c:2312
 async_btree_node_rewrite_work+0x110/0x4f0 fs/bcachefs/btree_update_interior.c:2369
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:journal_seq_pin fs/bcachefs/journal_reclaim.h:30 [inline]
RIP: 0010:bch2_journal_pin_set_locked+0x346/0x350 fs/bcachefs/journal_reclaim.c:422
Code: fe ff ff e8 3c 92 72 fd 48 c7 c7 e0 f5 78 8e 4c 89 e6 e8 bd 86 b3 00 e9 54 fe ff ff e8 23 92 72 fd 90 0f 0b e8 1b 92 72 fd 90 <0f> 0b e8 13 92 72 fd 90 0f 0b 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000256f6a0 EFLAGS: 00010293
RAX: ffffffff844d2945 RBX: ffff8880119ce108 RCX: ffff888032e4a440
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000005 R08: 0000000000000005 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520004adecc R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff888054049800
FS:  0000000000000000(0000) GS:ffff88808d211000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000564f7dae2a38 CR3: 0000000051967000 CR4: 0000000000352ef0


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