Re: [PATCH] powerpc/mm: Code cleanup for __hash_page_thp

[Kunwu Chan]

Thanks all for the reply.
On 2024/2/29 14:18, Michael Ellerman wrote:
> Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxx> writes:
> > Michael Ellerman <mpe@xxxxxxxxxxxxxx> writes:
> > > Kunwu Chan <chentao@xxxxxxxxxx> writes:
> > > > On 2024/2/26 18:49, Michael Ellerman wrote:
> > > > > Kunwu Chan <chentao@xxxxxxxxxx> writes:
> > > > > > This part was commented from commit 6d492ecc6489
> > > > > > ("powerpc/THP: Add code to handle HPTE faults for hugepages")
> > > > > > in about 11 years before.
> > > > > >
> > > > > > If there are no plans to enable this part code in the future,
> > > > > > we can remove this dead code.
> > > > >
> > > > > I agree the code can go. But I'd like it to be replaced with a comment
> > > > > explaining what the dead code was trying to say.
> > >
> > > > Thanks, i'll update a new patch with the following comment:
> > > >       /*
> > > >       * No CPU has hugepages but lacks no execute, so we
> > > >       * don't need to worry about cpu no CPU_FTR_COHERENT_ICACHE feature case
> > > >       */
> > >
> > > Maybe wait until we can get some input from Aneesh. I'm not sure the
> > > code/comment are really up to date.
> >
> > How about?
> >
> > modified   arch/powerpc/mm/book3s64/hash_hugepage.c
> > @@ -58,17 +58,13 @@ int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid,
> >   		return 0;
> >   
> >   	rflags = htab_convert_pte_flags(new_pmd, flags);
> > +	/*
> > +	 * THPs are only supported on platforms that can do mixed page size
> > +	 * segments (MPSS) and all such platforms have coherent icache. Hence we
> > +	 * don't need to do lazy icache flush (hash_page_do_lazy_icache()) on
> > +	 * noexecute fault.
> > +	 */
I'll use this comment in v2 patch.
And add two Suggested-by: label for you.

> Yeah thanks that looks good.
>
> It could say "see eg. __hash_page_4K()", but that's probably unnecessary
> as it mentions hash_page_do_lazy_icache(), and anyone interested is just
> going to grep for that anyway.
>
> cheers
--
Thanks,
  Kunwu