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Subject: Re: [PATCH v2 1/5] mm: page_alloc: remain memblock_next_valid_pfn()
 when CONFIG_HAVE_ARCH_PFN_VALID is enable
To:     Daniel Vacek <neelx@redhat.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@suse.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Mel Gorman <mgorman@suse.de>,
        Will Deacon <will.deacon@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Pavel Tatashin <pasha.tatashin@oracle.com>,
        Daniel Jordan <daniel.m.jordan@oracle.com>,
        AKASHI Takahiro <takahiro.akashi@linaro.org>,
        Gioh Kim <gi-oh.kim@profitbricks.com>,
        Steven Sistare <steven.sistare@oracle.com>,
        Eugeniu Rosca <erosca@de.adit-jv.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        open list <linux-kernel@vger.kernel.org>, linux-mm@kvack.org,
        James Morse <james.morse@arm.com>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Steve Capper <steve.capper@arm.com>, x86@kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Kate Stewart <kstewart@linuxfoundation.org>,
        Philippe Ombredanne <pombredanne@nexb.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Kemi Wang <kemi.wang@intel.com>,
        Petr Tesarik <ptesarik@suse.com>,
        YASUAKI ISHIMATSU <yasu.isimatu@gmail.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Nikolay Borisov <nborisov@suse.com>,
        Jia He <jia.he@hxt-semitech.com>
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 <1521894282-6454-2-git-send-email-hejianet@gmail.com>
 <CACjP9X-zvGa5OQpuJ1bUp+V=_eTOUDLfKkT1sbT84k5zJz=epA@mail.gmail.com>
From:   Jia He <hejianet@gmail.com>
Message-ID: <0a8ba07b-b046-c1b4-9c4e-74d7b5dc370e@gmail.com>
Date:   Wed, 28 Mar 2018 09:49:53 +0800
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On 3/28/2018 12:52 AM, Daniel Vacek Wrote:
> On Sat, Mar 24, 2018 at 1:24 PM, Jia He <hejianet@gmail.com> wrote:
>> Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns
>> where possible") optimized the loop in memmap_init_zone(). But it causes
>> possible panic bug. So Daniel Vacek reverted it later.
>>
>> But memblock_next_valid_pfn is valid when CONFIG_HAVE_ARCH_PFN_VALID is
>> enabled. And as verified by Eugeniu Rosca, arm can benifit from this
>> commit. So remain the memblock_next_valid_pfn.
> It is not dependent on CONFIG_HAVE_ARCH_PFN_VALID option but on
> arm(64) implementation of pfn_valid() function, IIUC. So it should
> really be moved from generic source file to arm specific location. I'd
> say somewhere close to the pfn_valid() implementation. Such as to
> arch/arm{,64}/mm/ init.c-ish?
>
> --nX
Ok, thanks for your suggestions.
I will try to move the  related codes to arm arch directory.

Cheer,
Jia