------------[ cut here ]------------
WARNING: CPU: 1 PID: 3007 at block/bio.c:513 bio_alloc_bioset+0x444/0x8b0 block/bio.c:513
Modules linked in:
CPU: 1 UID: 0 PID: 3007 Comm: kworker/u8:7 Not tainted 6.16.0-rc1-syzkaller-00101-g27605c8c0f69 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: writeback wb_workfn (flush-bcachefs-2)
RIP: 0010:bio_alloc_bioset+0x444/0x8b0 block/bio.c:513
Code: 7c 24 18 e9 a0 fd ff ff e8 d9 01 07 fd 0f b7 6c 24 48 31 ff 89 ee e8 db fc 06 fd 66 85 ed 0f 84 67 fc ff ff e8 bd 01 07 fd 90 <0f> 0b 90 31 ed e9 a4 fe ff ff e8 ad 01 07 fd 48 8b 74 24 08 45 89
RSP: 0018:ffffc9000b2c7320 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff8880760c8948 RCX: ffffffff84b50a35
RDX: ffff888030e60000 RSI: ffffffff84b50a43 RDI: 0000000000000003
RBP: 0000000000000100 R08: 0000000000000003 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000001 R12: 0000000000000001
R13: 1ffff92001658e69 R14: dffffc0000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff88812485b000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f59bffc1d18 CR3: 0000000029da8000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 bch2_writepage_io_alloc fs/bcachefs/fs-io-buffered.c:502 [inline]
 __bch2_writepage+0xf9f/0x1e20 fs/bcachefs/fs-io-buffered.c:636
 write_cache_pages+0xb2/0x130 mm/page-writeback.c:2614
 bch2_writepages+0x10b/0x210 fs/bcachefs/fs-io-buffered.c:666
 do_writepages+0x27a/0x600 mm/page-writeback.c:2636
 __writeback_single_inode+0x160/0xfb0 fs/fs-writeback.c:1680
 writeback_sb_inodes+0x601/0xf90 fs/fs-writeback.c:1976
 wb_writeback+0x419/0xb70 fs/fs-writeback.c:2156
 wb_do_writeback fs/fs-writeback.c:2303 [inline]
 wb_workfn+0x14d/0xbe0 fs/fs-writeback.c:2343
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3238
 process_scheduled_works kernel/workqueue.c:3321 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3402
 kthread+0x3c5/0x780 kernel/kthread.c:464
 ret_from_fork+0x5d7/0x6f0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>