------------[ cut here ]------------
WARNING: CPU: 0 PID: 13 at block/bio.c:513 bio_alloc_bioset+0xd45/0x1110 block/bio.c:513
Modules linked in:
CPU: 0 UID: 0 PID: 13 Comm: kworker/u8:1 Not tainted 6.15.0-syzkaller-07774-g90b83efa6701 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: writeback wb_workfn (flush-bcachefs-1)
RIP: 0010:bio_alloc_bioset+0xd45/0x1110 block/bio.c:513
Code: db f6 ff 81 ce 00 20 09 00 e8 97 34 80 fd 48 85 c0 0f 84 8b 00 00 00 49 89 c7 e8 76 20 2a fd e9 65 f8 ff ff e8 6c 20 2a fd 90 <0f> 0b 90 e9 41 fb ff ff e8 5e 20 2a fd 90 0f 0b 90 e9 04 fb ff ff
RSP: 0000:ffffc90000126db8 EFLAGS: 00010293
RAX: ffffffff8495d994 RBX: 0000000000000000 RCX: ffff88801cef8000
RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000000
RBP: dffffc0000000000 R08: ffff888073a48908 R09: 1ffffd4000395968
R10: dffffc0000000000 R11: fffff94000395969 R12: 0000000000000001
R13: ffff888073a48908 R14: ffff888073a48a20 R15: 0000000000000100
FS:  0000000000000000(0000) GS:ffff888125c98000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f05b20a4000 CR3: 000000003174e000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 bch2_writepage_io_alloc fs/bcachefs/fs-io-buffered.c:510 [inline]
 __bch2_writepage+0x1581/0x2790 fs/bcachefs/fs-io-buffered.c:644
 write_cache_pages+0x64/0x100 mm/page-writeback.c:2613
 bch2_writepages+0x154/0x360 fs/bcachefs/fs-io-buffered.c:675
 do_writepages+0x32b/0x550 mm/page-writeback.c:2635
 __writeback_single_inode+0x145/0xff0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x6b5/0x1000 fs/fs-writeback.c:1976
 __writeback_inodes_wb+0x111/0x240 fs/fs-writeback.c:2047
 wb_writeback+0x44f/0xaf0 fs/fs-writeback.c:2158
 wb_check_old_data_flush fs/fs-writeback.c:2262 [inline]
 wb_do_writeback fs/fs-writeback.c:2315 [inline]
 wb_workfn+0xaef/0xef0 fs/fs-writeback.c:2343
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>