------------[ cut here ]------------
truncate spotted in mem i_size < btree i_size: 65535 < 1048576
WARNING: CPU: 0 PID: 6878 at fs/bcachefs/fs-io.c:472 bchfs_truncate+0x88c/0xa70 fs/bcachefs/fs-io.c:469
Modules linked in:
CPU: 0 UID: 0 PID: 6878 Comm: syz.4.62 Not tainted 6.15.0-rc7-syzkaller-gd7fa1af5b33e #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : bchfs_truncate+0x88c/0xa70 fs/bcachefs/fs-io.c:469
lr : bchfs_truncate+0x88c/0xa70 fs/bcachefs/fs-io.c:469
sp : ffff8000a2d27760
x29: ffff8000a2d279f0 x28: 0000000000100000 x27: ffff0000ff1787c8
x26: ffff0000ff178c40 x25: ffff8000a2d27b70 x24: ffff7000145a4efc
x23: 000000000000ffff x22: ffff0000ff178d00 x21: ffff0000ff178c38
x20: dfff800000000000 x19: ffff0000ff178798 x18: 00000000ffffffff
x17: 0000000000000000 x16: ffff80008ad27e48 x15: ffff700011e740c0
x14: 1ffff00011e740c0 x13: 0000000000000004 x12: ffffffffffffffff
x11: ffff700011e740c0 x10: 0000000000ff0100 x9 : 9cb0652c0a430e00
x8 : 9cb0652c0a430e00 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff8000a2d270b8 x4 : ffff80008f415ba0 x3 : ffff800080548ef0
x2 : 0000000000000000 x1 : 0000000100000000 x0 : 0000000000000000
Call trace:
 bchfs_truncate+0x88c/0xa70 fs/bcachefs/fs-io.c:469 (P)
 bch2_setattr+0x198/0x20c fs/bcachefs/fs.c:1245
 notify_change+0x9a4/0xc50 fs/attr.c:552
 do_truncate+0x178/0x1f0 fs/open.c:65
 do_ftruncate+0x3bc/0x458 fs/open.c:192
 do_sys_ftruncate fs/open.c:207 [inline]
 __do_sys_ftruncate fs/open.c:212 [inline]
 __se_sys_ftruncate fs/open.c:210 [inline]
 __arm64_sys_ftruncate+0x90/0xe8 fs/open.c:210
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767
 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
irq event stamp: 79048
hardirqs last  enabled at (79047): [<ffff80008055041c>] __up_console_sem kernel/printk/printk.c:344 [inline]
hardirqs last  enabled at (79047): [<ffff80008055041c>] __console_unlock+0x70/0xc4 kernel/printk/printk.c:2885
hardirqs last disabled at (79048): [<ffff80008adb9eb8>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:511
softirqs last  enabled at (78984): [<ffff8000801fbf10>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (78982): [<ffff8000801fbedc>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
---[ end trace 0000000000000000 ]---