From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f70.google.com (mail-oo1-f70.google.com [209.85.161.70]) (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 3B83C430BAA for ; Mon, 2 Mar 2026 18:45:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.70 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772477143; cv=none; b=SDPkItYSMmO2snhl7mvWGs+WzFmruDAiHQST09Ja3gOEatEpNSlMNTWCQlgH1RlbhQrZOv4t/2BzvETGKrE2cORcjp8NU/ljMcp6MAZgYXZZ6f2ZzNR/uiBBjPXB4UM5oINQ8N2bd8315EhODnv1q9pTrsvv6H7OOvZbD9iL0rg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772477143; c=relaxed/simple; bh=BNQWtdRHuO3S+gGOscSXOqbfLFQhgJQr/6SBZrjZhek=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=D0DZx0kknIJsYfVR/kGCu+BaN3FYKG0SbKeCGVDJDAGaoKQX8HNbcmz7L6DKrq/lkd1tJoygJLRG5zHwxI+VPmdFW8ER6eATAJ/s8RgdbJhyaf1Fpfv3OuORdMmA9oIB3tSo/HxbU48CUe/mSaep4m1rawQSZO7nl0eXC7/JLP8= 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=209.85.161.70 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-oo1-f70.google.com with SMTP id 006d021491bc7-679dda090fbso97352362eaf.2 for ; Mon, 02 Mar 2026 10:45:42 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772477141; x=1773081941; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=KKp7i17aMM9L6WuRWWndlSaZEHbB7jCUXWvpqpj5i2M=; b=bjI1jExgWBswQHmn63pmIMQ93+EVTqQCDDcrsjzsJyAYwQbsHGxhRqk+XXgUSHawzM BKxjDZN40Fe4ALQ+KlGjcdMHRqmolThQs7IRoENphkGJMWI9jOld7HneNEZXcbX8POvQ 0spXTtuUuy/TnWe9d5eyDdwd6DRRjpwKldvPb2ZYFcE3GEBTlaeeMMK7tqEBlALga4/S WHowJl1lTVTIueAuDW9Cs+QoT8KZvcJkbCm8dMlhAcVO89nKBHXF0F/1YS6LhbcBLDv5 O/gO9yZXDziXHaC8PXnBLud4dpdXKQ4DS5hJkVYgx8VeiQYZYsjfUsHJK/KFpIGUmdQe AW0w== X-Forwarded-Encrypted: i=1; AJvYcCX/oRo+YwGreULF3Rn8YexlVx+Y6Zg11/GlzF9vaPI0ybLlzLWtvrW5TiOD4PrKFMSZ1CPwBpjPGn6DZA==@vger.kernel.org X-Gm-Message-State: AOJu0YzoX3jCfziGSJQRIPpwTYlORkYm/79blMWAgGSS5BcjYLix2Zzf QOfEXDt755ALkXUnbdvbdjN4GC2BGRmzZ9jQWz/P4kp32iRtBsOPsczPHBoJWlhlkEXHEaBdphB 4vbq0/5xwBfVGtfNk17yxGWODh98fbJ8BTuQlT/rKKlyDy2HUmDBYw+0JLZ0= Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:98e:b0:662:f91f:4a98 with SMTP id 006d021491bc7-679faf3a953mr7150262eaf.41.1772477141288; Mon, 02 Mar 2026 10:45:41 -0800 (PST) Date: Mon, 02 Mar 2026 10:45:41 -0800 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69a5dad5.a70a0220.b118c.0001.GAE@google.com> Subject: [syzbot] [btrfs?] WARNING: suspicious RCU usage in btrfs_device_init_dev_stats 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: 7d6661873f6b Add linux-next specific files for 20260226 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=105ad1aa580000 kernel config: https://syzkaller.appspot.com/x/.config?x=98a1e192f758c1c1 dashboard link: https://syzkaller.appspot.com/bug?extid=d4957dbe80e471232035 compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/4cd2824adb8a/disk-7d666187.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/bbdd4a130d86/vmlinux-7d666187.xz kernel image: https://storage.googleapis.com/syzbot-assets/6e3bea3e96f8/bzImage-7d666187.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+d4957dbe80e471232035@syzkaller.appspotmail.com ============================= WARNING: suspicious RCU usage syzkaller #0 Not tainted ----------------------------- fs/btrfs/volumes.h:872 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 3 locks held by syz.2.1057/8526: #0: ffff88807cc920e0 (&type->s_umount_key#58/1){+.+.}-{4:4}, at: alloc_super+0x28c/0xab0 fs/super.c:345 #1: ffff888057f2e0d8 (&fs_devs->device_list_mutex){+.+.}-{4:4}, at: btrfs_init_dev_stats+0x5b/0x190 fs/btrfs/volumes.c:8157 #2: ffff8880772940f8 (btrfs-dev-00){.+.+}-{4:4}, at: btrfs_tree_read_lock_nested+0x33/0x250 fs/btrfs/locking.c:146 stack backtrace: CPU: 0 UID: 0 PID: 8526 Comm: syz.2.1057 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 lockdep_rcu_suspicious+0x13f/0x1d0 kernel/locking/lockdep.c:6876 btrfs_dev_name fs/btrfs/volumes.h:872 [inline] btrfs_dev_stat_print_on_load fs/btrfs/volumes.c:8302 [inline] btrfs_device_init_dev_stats+0x971/0xb90 fs/btrfs/volumes.c:8140 btrfs_init_dev_stats+0x8e/0x190 fs/btrfs/volumes.c:8159 open_ctree+0x1be9/0x2e40 fs/btrfs/disk-io.c:3534 btrfs_fill_super+0x187/0x2e0 fs/btrfs/super.c:981 btrfs_get_tree_super fs/btrfs/super.c:1944 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2087 [inline] btrfs_get_tree+0xe77/0x1370 fs/btrfs/super.c:2121 vfs_get_tree+0x92/0x2a0 fs/super.c:1754 fc_mount fs/namespace.c:1193 [inline] do_new_mount_fc fs/namespace.c:3763 [inline] do_new_mount+0x341/0xd30 fs/namespace.c:3839 do_mount fs/namespace.c:4172 [inline] __do_sys_mount fs/namespace.c:4361 [inline] __se_sys_mount+0x31d/0x420 fs/namespace.c:4338 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f197b19da0a Code: 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007f197bf8be58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f197bf8bee0 RCX: 00007f197b19da0a RDX: 0000200000005100 RSI: 0000200000000040 RDI: 00007f197bf8bea0 RBP: 0000200000005100 R08: 00007f197bf8bee0 R09: 0000000000a08811 R10: 0000000000a08811 R11: 0000000000000246 R12: 0000200000000040 R13: 00007f197bf8bea0 R14: 0000000000005163 R15: 0000200000000100 BTRFS info (device loop2 state ECS): bdev /dev/loop2 errs: wr 150994944, rd 0, flush 0, corrupt 0, gen 0 BTRFS info (device loop2 state ECS): setting nodatasum BTRFS info (device loop2 state ECS): disabling tree log BTRFS info (device loop2 state ECS): enabling free space tree BTRFS info (device loop2 state ECS): ignoring bad roots BTRFS info (device loop2 state ECS): ignoring meta csums --- 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