------------[ cut here ]------------
WARNING: CPU: 0 PID: 10829 at fs/bcachefs/fs-io.c:361 __bch2_truncate_folio+0x179c/0x1a30
Modules linked in:
CPU: 0 UID: 0 PID: 10829 Comm: syz.7.622 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:__bch2_truncate_folio+0x179c/0x1a30
Code: 5f 5d e9 17 07 3d 07 cc e8 11 aa 7f fd 48 c7 c7 ca a7 a3 8d e8 85 61 e9 ff 89 05 5f 39 86 15 e9 49 ea ff ff e8 f5 a9 7f fd 90 <0f> 0b 90 e9 26 f9 ff ff e8 f7 21 3a 07 e8 e2 a9 7f fd be 00 10 00
RSP: 0018:ffffc900069c79e0 EFLAGS: 00010283
RAX: ffffffff844004eb RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc90023af2000 RSI: 0000000000000f28 RDI: 0000000000000f29
RBP: ffffc900069c7bb0 R08: ffffea00008a9f87 R09: 1ffffd40001153f0
R10: dffffc0000000000 R11: fffff940001153f1 R12: 1ffff110227ddb6e
R13: dffffc0000000000 R14: ffff888113eedb70 R15: 0000000000000000
FS:  00007f12c43586c0(0000) GS:ffff8880b8615000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000000080 CR3: 000000011c3da000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 bchfs_fallocate+0x233/0x680
 bch2_fallocate_dispatch+0x28a/0x410
 vfs_fallocate+0x669/0x7e0
 __x64_sys_fallocate+0xc0/0x110
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f12c358ebe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f12c4358038 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007f12c37c5fa0 RCX: 00007f12c358ebe9
RDX: 0000000000000002 RSI: 0000000000000010 RDI: 0000000000000005
RBP: 00007f12c3611e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000007fff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f12c37c6038 R14: 00007f12c37c5fa0 R15: 00007fff35ad4b68
 </TASK>
