Re: [PATCH 3/3] x86/fpu: Remove init_task FPU state dependencies, add debugging warning

[Oleg Nesterov]

On 06/05, Linus Torvalds wrote:
>
> On Wed, 5 Jun 2024 at 07:19, Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
> >
> > On 06/05, Ingo Molnar wrote:
> > >
> > > But the init task isn't supposed to be using the FPU in any case,
> >
> > Afaics, the same is true for any PF_KTHREAD/USER_WORKER thread?
>
> I don't think so. We have various users of kernel_fpu_begin()/end()
> that are very much about things like crypto and RAID xor memory copies
> etc that will be used by kernel worker threads.

Yes, but kernel_fpu_begin() never does save_fpregs_to_fpstate() if
current->flags & PF_KTHREAD ?

Oleg.