linux-kernel - Re: [PATCH v5 09/11] hugetlb: Introduce generic version of huge_ptep_set

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Message-ID: <ef7fbd80-84a9-0b39-f948-413dea6f6469@ghiti.fr>
Date:   Fri, 3 Aug 2018 11:47:10 +0200
From:   Alexandre Ghiti <alex@...ti.fr>
To:     Michael Ellerman <mpe@...erman.id.au>, linux-mm@...ck.org,
        mike.kravetz@...cle.com, linux@...linux.org.uk,
        catalin.marinas@....com, will.deacon@....com, tony.luck@...el.com,
        fenghua.yu@...el.com, ralf@...ux-mips.org, paul.burton@...s.com,
        jhogan@...nel.org, jejb@...isc-linux.org, deller@....de,
        benh@...nel.crashing.org, ysato@...rs.sourceforge.jp,
        dalias@...c.org, davem@...emloft.net, tglx@...utronix.de,
        mingo@...hat.com, hpa@...or.com, x86@...nel.org, arnd@...db.de,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-ia64@...r.kernel.org, linux-mips@...ux-mips.org,
        linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
        linux-arch@...r.kernel.org,
        "aneesh.kumar@...ux.ibm.com" <aneesh.kumar@...ux.ibm.com>
Subject: Re: [PATCH v5 09/11] hugetlb: Introduce generic version of
 huge_ptep_set_wrprotect

Hi Michael,

Thanks, I will then remove those two specific implementations and we'll 
use the generic ones.

I send a v6 asap.

Thanks again,

Alex


On 08/03/2018 10:51 AM, Michael Ellerman wrote:
> Hi Alex,
>
> Sorry missed your previous mail.
>
> Alex Ghiti <alex@...ti.fr> writes:
>> Ok, I tried every defconfig available:
>>
>> - for the nohash/32, I found that I could use mpc885_ads_defconfig and I
>> activated HUGETLBFS.
>> I removed the definition of huge_ptep_set_wrprotect from
>> nohash/32/pgtable.h, add an #error in
>> include/asm-generic/hugetlb.h right before the generic definition of
>> huge_ptep_set_wrprotect,
>> and fell onto it at compile-time:
>> => I'm pretty confident then that removing the definition of
>> huge_ptep_set_wrprotect does not
>> break anythingin this case.
> Thanks, that sounds good.
>
>> - regardind book3s/32, I did not find any defconfig with
>> CONFIG_PPC_BOOK3S_32, CONFIG_PPC32
>> allowing to enable huge page support (ie CONFIG_SYS_SUPPORTS_HUGETLBFS)
>> => Do you have a defconfig that would allow me to try the same as above ?
> I think you're right, it's dead code AFAICS.
>
> We have:
>
> config PPC_BOOK3S_64
>          ...
> 	select SYS_SUPPORTS_HUGETLBFS
>
> config PPC_FSL_BOOK3E
>          ...
> 	select SYS_SUPPORTS_HUGETLBFS if PHYS_64BIT || PPC64
>
> config PPC_8xx
> 	...
> 	select SYS_SUPPORTS_HUGETLBFS
>
>
> So we can't ever enable HUGETLBFS for Book3S 32.
>
> Presumably the code got copied when we split the headers apart.
>
> So I think you can just ignore that one, and we'll delete it.
>
> cheers