linux-kernel - [syzbot] [btrfs?] kernel BUG in populate_free_space

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Message-ID: <6841dca8.a00a0220.d4325.0020.GAE@google.com>
Date: Thu, 05 Jun 2025 11:06:32 -0700
From: syzbot <syzbot+36fae25c35159a763a2a@...kaller.appspotmail.com>
To: clm@...com, dsterba@...e.com, josef@...icpanda.com, 
	linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [btrfs?] kernel BUG in populate_free_space_tree

Hello,

syzbot found the following issue on:

HEAD commit:    d7fa1af5b33e Merge branch 'for-next/core' into for-kernelci
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=17ab4c0c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=89c13de706fbf07a
dashboard link: https://syzkaller.appspot.com/bug?extid=36fae25c35159a763a2a
compiler:       Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
userspace arch: arm64
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12b79282580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=106b4c0c580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/da97ad659b2c/disk-d7fa1af5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/659e123552a8/vmlinux-d7fa1af5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6ec5dbf4643e/Image-d7fa1af5.gz.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/643a65f1a5eb/mount_0.gz
  fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=11f86570580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+36fae25c35159a763a2a@...kaller.appspotmail.com

BTRFS warning: 'usebackuproot' is deprecated, use 'rescue=usebackuproot' instead
BTRFS info (device loop0 state M): rebuilding free space tree
assertion failed: ret == 0, in fs/btrfs/free-space-tree.c:1102
------------[ cut here ]------------
kernel BUG at fs/btrfs/free-space-tree.c:1102!
Internal error: Oops - BUG: 00000000f2000800 [#1]  SMP
Modules linked in:
CPU: 1 UID: 0 PID: 6592 Comm: syz-executor322 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 : populate_free_space_tree+0x514/0x518 fs/btrfs/free-space-tree.c:1102
lr : populate_free_space_tree+0x514/0x518 fs/btrfs/free-space-tree.c:1102
sp : ffff8000a4ce7600
x29: ffff8000a4ce76e0 x28: ffff0000c9bc6000 x27: ffff0000ddfff3d8
x26: ffff0000ddfff378 x25: dfff800000000000 x24: 0000000000000001
x23: ffff8000a4ce7660 x22: ffff70001499cecc x21: ffff0000e1d8c160
x20: ffff0000e1cb7800 x19: ffff0000e1d8c0b0 x18: 00000000ffffffff
x17: ffff800092f39000 x16: ffff80008ad27e48 x15: ffff700011e740c0
x14: 1ffff00011e740c0 x13: 0000000000000004 x12: ffffffffffffffff
x11: ffff700011e740c0 x10: 0000000000ff0100 x9 : 94ef24f55d2dbc00
x8 : 94ef24f55d2dbc00 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff8000a4ce6f98 x4 : ffff80008f415ba0 x3 : ffff800080548ef0
x2 : 0000000000000000 x1 : 0000000100000000 x0 : 000000000000003e
Call trace:
 populate_free_space_tree+0x514/0x518 fs/btrfs/free-space-tree.c:1102 (P)
 btrfs_rebuild_free_space_tree+0x14c/0x54c fs/btrfs/free-space-tree.c:1337
 btrfs_start_pre_rw_mount+0xa78/0xe10 fs/btrfs/disk-io.c:3074
 btrfs_remount_rw fs/btrfs/super.c:1319 [inline]
 btrfs_reconfigure+0x828/0x2418 fs/btrfs/super.c:1543
 reconfigure_super+0x1d4/0x6f0 fs/super.c:1083
 do_remount fs/namespace.c:3365 [inline]
 path_mount+0xb34/0xde0 fs/namespace.c:4200
 do_mount fs/namespace.c:4221 [inline]
 __do_sys_mount fs/namespace.c:4432 [inline]
 __se_sys_mount fs/namespace.c:4409 [inline]
 __arm64_sys_mount+0x3e8/0x468 fs/namespace.c:4409
 __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
Code: f0047182 91178042 528089c3 9771d47b (d4210000) 
---[ end trace 0000000000000000 ]---


---
This report is generated by a bot. It may contain errors.
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