Re: [PATCH 3/3] x86: avoid copying dynamic FP state from init_task

[Ingo Molnar <mingo@kernel.org>]

* Benjamin Berg <benjamin@sipsolutions.net> wrote:

> > Note that this patch, while it still applies cleanly, crashes/hangs 
> > the x86-64 defconfig kernel bootup in the early boot phase in a KVM 
> > guest bootup.
> 
> Oh, outch. It seems that arch_task_struct_size can actually become 
> smaller than sizeof(init_task) if the CPU does not have certain 
> features.
> 
> See fpu__init_task_struct_size, which does:
> 
>   int task_size = sizeof(struct task_struct);
>   task_size -= sizeof(current->thread.fpu.__fpstate.regs);
>   task_size += fpu_kernel_cfg.default_size;
> 
> I'll submit a new version of the patch and then also switch to use
> memcpy_and_pad.

Thank you!

	Ingo