Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Sun, 13 Jan 2019 18:35:55 +0100
From:   Michal Hocko <mhocko@kernel.org>
To:     Anshuman Khandual <anshuman.khandual@arm.com>
Cc:     linux-mm@kvack.org, akpm@linux-foundation.org,
        linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
        linux-arm-kernel@lists.infradead.org, linux-sh@vger.kernel.org,
        kvmarm@lists.cs.columbia.edu, linux@armlinux.org.uk,
        catalin.marinas@arm.com, will.deacon@arm.com, mpe@ellerman.id.au,
        tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com,
        peterz@infradead.org, christoffer.dall@arm.com,
        marc.zyngier@arm.com, kirill@shutemov.name,
        rppt@linux.vnet.ibm.com, ard.biesheuvel@linaro.org,
        mark.rutland@arm.com, steve.capper@arm.com, james.morse@arm.com,
        robin.murphy@arm.com, aneesh.kumar@linux.ibm.com, vbabka@suse.cz,
        shakeelb@google.com, rientjes@google.com
Subject: Re: [PATCH] mm: Introduce GFP_PGTABLE
Message-ID: <20190113173555.GC1578@dhcp22.suse.cz>
References: <1547288798-10243-1-git-send-email-anshuman.khandual@arm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1547288798-10243-1-git-send-email-anshuman.khandual@arm.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Sat 12-01-19 15:56:38, Anshuman Khandual wrote:
> All architectures have been defining their own PGALLOC_GFP as (GFP_KERNEL |
> __GFP_ZERO) and using it for allocating page table pages. This causes some
> code duplication which can be easily avoided. GFP_KERNEL allocated and
> cleared out pages (__GFP_ZERO) are required for page tables on any given
> architecture. This creates a new generic GFP flag flag which can be used
> for any page table page allocation. Does not cause any functional change.

I agree that some unification is due but GFP_PGTABLE is not something to
expose in generic gfp.h IMHO. It just risks an abuse. I would be looking
at providing asm-generic implementation and reuse it to remove the code
duplication. But I haven't tried that to know that it will work out due
to small/subtle differences between arches.

> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
-- 
Michal Hocko
SUSE Labs