------------[ cut here ]------------
truncate spotted in mem i_size < btree i_size: 1 < 65536
WARNING: CPU: 0 PID: 32096 at fs/bcachefs/fs-io.c:434 bchfs_truncate+0x7ad/0xd70 fs/bcachefs/fs-io.c:434
Modules linked in:
CPU: 0 PID: 32096 Comm: syz-executor.1 Not tainted 6.9.0-syzkaller-07726-g3c999d1ae3c7 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:bchfs_truncate+0x7ad/0xd70 fs/bcachefs/fs-io.c:434
Code: 24 38 84 c0 0f 85 d3 fc ff ff e8 2e 0c 90 fd c6 05 45 22 cd 0b 01 90 48 c7 c7 00 5c 7f 8b 4c 89 ea 4c 89 fe e8 e4 8a 52 fd 90 <0f> 0b 90 90 48 b8 00 00 00 00 00 fc ff df 48 8b 54 24 48 48 c1 ea
RSP: 0018:ffffc90003fbf758 EFLAGS: 00010282
RAX: 0000000000000000 RBX: ffff888063a90548 RCX: ffffc90023dc2000
RDX: 0000000000040000 RSI: ffffffff81510486 RDI: 0000000000000001
RBP: ffffc90003fbf920 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000002 R12: ffff888063a90000
R13: 0000000000010000 R14: ffffc90003fbfa18 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff88802c000000(0063) knlGS:00000000f5ebcb40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 000000002c143000 CR3: 0000000064638000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 bch2_setattr+0x1ab/0x250 fs/bcachefs/fs.c:885
 notify_change+0x742/0x11c0 fs/attr.c:497
 do_truncate+0x15c/0x220 fs/open.c:65
 handle_truncate fs/namei.c:3308 [inline]
 do_open fs/namei.c:3654 [inline]
 path_openat+0x24b9/0x2990 fs/namei.c:3807
 do_filp_open+0x1dc/0x430 fs/namei.c:3834
 do_sys_openat2+0x17a/0x1e0 fs/open.c:1406
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_creat fs/open.c:1497 [inline]
 __se_sys_creat fs/open.c:1491 [inline]
 __ia32_sys_creat+0xcc/0x120 fs/open.c:1491
 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
 __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf72eb579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f5ebc5ac EFLAGS: 00000292 ORIG_RAX: 0000000000000008
RAX: ffffffffffffffda RBX: 00000000200000c0 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	10 06                	adc    %al,(%rsi)
   2:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
   6:	10 07                	adc    %al,(%rdi)
   8:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
   c:	10 08                	adc    %cl,(%rax)
   e:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
  1e:	00 51 52             	add    %dl,0x52(%rcx)
  21:	55                   	push   %rbp
  22:	89 e5                	mov    %esp,%ebp
  24:	0f 34                	sysenter
  26:	cd 80                	int    $0x80
* 28:	5d                   	pop    %rbp <-- trapping instruction
  29:	5a                   	pop    %rdx
  2a:	59                   	pop    %rcx
  2b:	c3                   	ret
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	90                   	nop
  2f:	90                   	nop
  30:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
  37:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi