------------[ cut here ]------------
WARNING: CPU: 0 PID: 5367 at fs/bcachefs/fs-io.c:361 __bch2_truncate_folio+0x179c/0x1a30 fs/bcachefs/fs-io.c:361
Modules linked in:
CPU: 0 UID: 0 PID: 5367 Comm: syz.0.0 Not tainted syzkaller #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
RIP: 0010:__bch2_truncate_folio+0x179c/0x1a30 fs/bcachefs/fs-io.c:361
Code: 5f 5d e9 47 39 3d 07 cc e8 61 4b 7e fd 48 c7 c7 23 cd a3 8d e8 85 61 e9 ff 89 05 8f 4f 85 15 e9 49 ea ff ff e8 45 4b 7e fd 90 <0f> 0b 90 e9 26 f9 ff ff e8 27 54 3a 07 e8 32 4b 7e fd be 00 10 00
RSP: 0018:ffffc9000d34f9e0 EFLAGS: 00010283
RAX: ffffffff844172bb RBX: 0000000000000000 RCX: 0000000000100000
RDX: ffffc9000ef89000 RSI: 0000000000000ddb RDI: 0000000000000ddc
RBP: ffffc9000d34fbb0 R08: ffffea0001484007 R09: 1ffffd4000290800
R10: dffffc0000000000 R11: fffff94000290801 R12: 1ffff1100a8032e3
R13: dffffc0000000000 R14: ffff888054019718 R15: 0000000000000000
FS:  00007f5e6b3f56c0(0000) GS:ffff88808d20d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5e6b3f4fc8 CR3: 0000000043dd0000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 bch2_truncate_folios fs/bcachefs/fs-io.c:400 [inline]
 bchfs_fallocate+0x233/0x680 fs/bcachefs/fs-io.c:777
 bch2_fallocate_dispatch+0x28a/0x410 fs/bcachefs/fs-io.c:836
 vfs_fallocate+0x666/0x7e0 fs/open.c:342
 ksys_fallocate fs/open.c:366 [inline]
 __do_sys_fallocate fs/open.c:371 [inline]
 __se_sys_fallocate fs/open.c:369 [inline]
 __x64_sys_fallocate+0xc0/0x110 fs/open.c:369
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5e6ef8ebe9
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:00007f5e6b3f5038 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 00007f5e6f1c6090 RCX: 00007f5e6ef8ebe9
RDX: 0000000000000002 RSI: 0000000000000010 RDI: 0000000000000006
RBP: 00007f5e6f011e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000007fff R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5e6f1c6128 R14: 00007f5e6f1c6090 R15: 00007ffcf3b8eba8
 </TASK>