Re: [syzbot] [block?] WARNING in wbt_init_enable_default

[Ming Lei]

On Thu, Feb 12, 2026 at 12:41:30PM -0800, syzbot wrote:
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    37a93dd5c49b Merge tag 'net-next-7.0' of git://git.kernel...
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=14342c02580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=a512b4a06724b76a
> dashboard link: https://syzkaller.appspot.com/bug?extid=71fcf20f7c1e5043d78c
> compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16ffbdb2580000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11542eef980000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/0dedaafff2ad/disk-37a93dd5.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/aa7fae081497/vmlinux-37a93dd5.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/9096b39b53e1/bzImage-37a93dd5.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+71fcf20f7c1e5043d78c@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> 0x000000000001-0x000000020000 : ""
> ftl_cs: FTL header corrupt!
> "mq-deadline" elevator initialization, failed -12, falling back to "none"
> ------------[ cut here ]------------
> !rwb
> WARNING: block/blk-wbt.c:784 at wbt_init_enable_default+0xcb/0x120 block/blk-wbt.c:784, CPU#0: syz.0.23/6066

The warning is expected given -ENOMEM is triggered from wbt_alloc(), either
kmalloc or percpu allocator.


Thanks,
Ming