Re: [syzbot] [btrfs?] WARNING: suspicious RCU usage in btrfs_dev_name

[David Sterba]

On Mon, Mar 02, 2026 at 12:01:42PM -0800, syzbot wrote:
> 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=11591952580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=98a1e192f758c1c1
> dashboard link: https://syzkaller.appspot.com/bug?extid=ba123cf1dd631315ffca
> 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+ba123cf1dd631315ffca@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> BTRFS info (device loop1): first mount of filesystem 7e32c2af-f87a-45a1-bcba-64dea7c56a53
> BTRFS info (device loop1): using xxhash64 checksum algorithm
> =============================
> WARNING: suspicious RCU usage
> syzkaller #0 Not tainted
> -----------------------------
> fs/btrfs/volumes.h:872 suspicious rcu_dereference_check() usage!

#syz invalid

Marking as invalid so it does not appear in the list of issues but
otherwise it's a valid report caused by patch that has been removed.

https://lore.kernel.org/linux-btrfs/20260205114546.210418-1-dsterba@xxxxxxxx/