From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f208.google.com (mail-oi1-f208.google.com [209.85.167.208]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BABB731714F for ; Sat, 25 Jul 2026 18:06:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.208 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785002788; cv=none; b=eiHAP1xy8OFkSQHyPzj/Kbzpnr0tKQP3nm8qdcUlRLygpwbOXVHuv1SDkcJJtEFCD4hjxy1ZQ0S4thFGON9ZsXJQ1do3UCgYCsjnAFlaLT0soq5yUTaUP0qPawMexWn5yQoo7k22DwkKDAM95pFG1gkxYEYKmSl2UIlwHqZ8Y8w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785002788; c=relaxed/simple; bh=XDt4EWlz36rUGzsVP3bs/XGPatV/qbXVAxuuuS4k0KQ=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=d5EYXJQYV2WV0hwsJ5girFBLdSegs3KpeCqhqiRe0ScxXyQatf9joxZU7eMmwSXhjuZZpD65+9OuotthbVjoayJ9h95zIbIw5bLM7HoQXeDBdW2T5/6fzVv4kux6f7XAtv9DSvXQSCvohErMoIhyhBJBC5irSe5rAmMlqowqKZE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.167.208 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oi1-f208.google.com with SMTP id 5614622812f47-49ab6a82cd5so2037465b6e.2 for ; Sat, 25 Jul 2026 11:06:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785002785; x=1785607585; h=content-type:to:from:subject:message-id:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=7ZDy09wiHC8UUs73jGqHYwI9KWgvrdpaQ6QB1ceyg2s=; b=CSQOqMTDN16flQT9W9NrUa2sRJ3awZGX2vf5wkp33BsW5c6Df1QSt360UW9hKTPgho yOYKs503tPOAb55GQ4tyRVGJ6K6toRQpM1o9Z3DOCetD29XKIu9Ggf4mUFdgpKViEzTl DOgld5DCO2rDRO3V4164ExQ5VbcoLkyZsUvloZHRMTgJT3XEnXJjdqai6tuPtvQ0f+LD QTB2TPna3vimzyL8UlbqLaqyWMwXQOCh+X2WGHUz+3aaJc3qsbLndBBbKysDTSJVvWeM ZzGzOqgvxvcz0mjRzLsauUSeVXr7rlJyPfR4fatYv5S9/koHiP2p7koVi0dTUVg6khCy BcCA== X-Forwarded-Encrypted: i=1; AHgh+Rq/5vrAlbUo8x9r0uZbkChZQCqkmefMhmBNVbvlPtdEnPL6VFUMLn1bSovOCNyTiFCVa6CJpzEl84CfyWk=@vger.kernel.org X-Gm-Message-State: AOJu0YymQ6IZaXZXjz8gvZ7ywCK4gn1u9okHX5fwlsi1qwTYCVvolk40 0wupcd5gUP54G4zmOuOPt+MN7bRYw51RnF1qB070/+W8R4Vu9ospbf8ybM0ev6gRsav9VPZmkXp W4syRmnZWmKY6x9ySuVFrO0skwgqhGyfIwPDxsJKYRVDg1pk/gp26n5CEGWw= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:220a:b0:49b:c387:36c5 with SMTP id 5614622812f47-4ab6a10d714mr3374919b6e.17.1785002785629; Sat, 25 Jul 2026 11:06:25 -0700 (PDT) Date: Sat, 25 Jul 2026 11:06:25 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a64fb21.073198cf.94f0f.0019.GAE@google.com> Subject: [syzbot] [btrfs?] WARNING in prepare_to_merge From: syzbot To: clm@fb.com, dsterba@suse.com, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: b95f03f04d47 Merge tag 'mm-hotfixes-stable-2026-07-20-11-3.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=148b4ab9580000 kernel config: https://syzkaller.appspot.com/x/.config?x=20c9876b0f77b546 dashboard link: https://syzkaller.appspot.com/bug?extid=bb14fd4ddd0269623f20 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-b95f03f0.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/46cc4d5161ad/vmlinux-b95f03f0.xz kernel image: https://storage.googleapis.com/syzbot-assets/4cb305677dbb/bzImage-b95f03f0.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+bb14fd4ddd0269623f20@syzkaller.appspotmail.com BTRFS info (device loop0): balance: start -d -m BTRFS info (device loop0): relocating block group 6881280 flags data|metadata ------------[ cut here ]------------ btrfs_abort_should_print_stack(__error) WARNING: fs/btrfs/relocation.c:1850 at prepare_to_merge+0x11a7/0x1740 fs/btrfs/relocation.c:1850, CPU#0: syz.0.0/5325 Modules linked in: CPU: 0 UID: 0 PID: 5325 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 04/01/2014 RIP: 0010:prepare_to_merge+0x11a7/0x1740 fs/btrfs/relocation.c:1850 Code: fc ef ff ff 4c 89 e7 e8 d7 24 0c fe e9 ef ef ff ff e8 1d 4b a8 07 e8 f8 f8 9c fd eb 10 e8 f1 f8 9c fd eb 09 e8 ea f8 9c fd 90 <0f> 0b 90 44 89 e1 f7 d9 4c 8b 6c 24 38 e9 5c f9 ff ff 89 f9 80 e1 RSP: 0018:ffffc9000e63f700 EFLAGS: 00010287 RAX: ffffffff842988e6 RBX: ffff888052c2c001 RCX: 0000000000100000 RDX: ffffc90020001000 RSI: 00000000000723ec RDI: 00000000000723ed RBP: ffffc9000e63f810 R08: ffff88801f4d2540 R09: 0000000000000003 R10: 00000000fffffffb R11: 0000000000000002 R12: 00000000ffffffe4 R13: ffff8880122865e8 R14: dffffc0000000000 R15: ffff88803fbda538 FS: 00007f43e4dd66c0(0000) GS:ffff88808c549000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000004478f000 CR4: 0000000000352ef0 Call Trace: relocate_block_group+0xbc6/0xe90 fs/btrfs/relocation.c:3700 do_nonremap_reloc+0xa7/0x560 fs/btrfs/relocation.c:5322 btrfs_relocate_block_group+0x6e2/0xaf0 fs/btrfs/relocation.c:5489 btrfs_relocate_chunk+0x114/0x810 fs/btrfs/volumes.c:3647 __btrfs_balance+0x1b5f/0x29d0 fs/btrfs/volumes.c:4586 btrfs_balance+0xaa6/0x1180 fs/btrfs/volumes.c:4973 btrfs_ioctl_balance+0x3da/0x640 fs/btrfs/ioctl.c:3480 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f43e3f9de99 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f43e4dd5fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f43e4226090 RCX: 00007f43e3f9de99 RDX: 0000200000000180 RSI: 00000000c4009420 RDI: 0000000000000008 RBP: 00007f43e4033eaf R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f43e4226128 R14: 00007f43e4226090 R15: 00007ffdeedc4388 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup