linux-kernel - Re: [PATCH v4 04/19] powerpc: mm: Add p?d

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Date:   Fri, 8 Mar 2019 10:50:42 +0000
From:   Steven Price <steven.price@....com>
To:     Mike Rapoport <rppt@...ux.ibm.com>
Cc:     Mark Rutland <Mark.Rutland@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Will Deacon <will.deacon@....com>, linux-mm@...ck.org,
        Paul Mackerras <paulus@...ba.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        "Liang, Kan" <kan.liang@...ux.intel.com>,
        Michael Ellerman <mpe@...erman.id.au>, x86@...nel.org,
        Ingo Molnar <mingo@...hat.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Arnd Bergmann <arnd@...db.de>, kvm-ppc@...r.kernel.org,
        Jérôme Glisse <jglisse@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-arm-kernel@...ts.infradead.org,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        linux-kernel@...r.kernel.org, James Morse <james.morse@....com>,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v4 04/19] powerpc: mm: Add p?d_large() definitions

On 08/03/2019 08:37, Mike Rapoport wrote:
> On Wed, Mar 06, 2019 at 03:50:16PM +0000, Steven Price wrote:
>> walk_page_range() is going to be allowed to walk page tables other than
>> those of user space. For this it needs to know when it has reached a
>> 'leaf' entry in the page tables. This information is provided by the
>> p?d_large() functions/macros.
>>
>> For powerpc pmd_large() was already implemented, so hoist it out of the
>> CONFIG_TRANSPARENT_HUGEPAGE condition and implement the other levels.
>>
>> Also since we now have a pmd_large always implemented we can drop the
>> pmd_is_leaf() function.
>>
>> CC: Benjamin Herrenschmidt <benh@...nel.crashing.org>
>> CC: Paul Mackerras <paulus@...ba.org>
>> CC: Michael Ellerman <mpe@...erman.id.au>
>> CC: linuxppc-dev@...ts.ozlabs.org
>> CC: kvm-ppc@...r.kernel.org
>> Signed-off-by: Steven Price <steven.price@....com>
>> ---
>>  arch/powerpc/include/asm/book3s/64/pgtable.h | 30 ++++++++++++++------
> 
> There is one more definition of pmd_large() in
> arch/powerpc/include/asm/pgtable.h

True. That is a #define so will work correctly (it will override the
generic version). Since it is only a dummy definition (always returns 0)
it could be removed, but that would need to be in a separate patch after
the asm-generic versions have been added to avoid breaking bisection.

Steve