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Subject: Re: Arm64 crash while reading memory sysfs
To:     Mike Rapoport <rppt@linux.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Qian Cai <quic_qiancai@quicinc.com>,
        David Hildenbrand <david@redhat.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>
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From:   Anshuman Khandual <anshuman.khandual@arm.com>
Message-ID: <daaf6faa-b5c1-b201-28c9-07f8e1fe4a82@arm.com>
Date:   Tue, 8 Jun 2021 12:36:21 +0530
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On 5/28/21 10:43 AM, Mike Rapoport wrote:
> On Thu, May 27, 2021 at 03:56:44PM -0700, Andrew Morton wrote:
>> On Thu, 27 May 2021 18:50:48 +0100 Catalin Marinas <catalin.marinas@arm.com> wrote:
>>
>>>> Can you please try Anshuman's patch "arm64/mm: Drop HAVE_ARCH_PFN_VALID":
>>>>
>>>> https://lore.kernel.org/lkml/1621947349-25421-1-git-send-email-anshuman.khandual@arm.com
>>>>
>>>> It seems to me that the check for memblock_is_memory() in
>>>> arm64::pfn_valid() is what makes init_unavailable_range() to bail out for
>>>> section parts that are not actually populated and then we have
>>>> VM_BUG_ON_PAGE(PagePoisoned(p)) for these pages.
>>>
>>> I acked Anshuman's patch, I think they all need to go in together.
>>
>> That's neat.   Specifically which patches are we referring to here?
> 
> arm64: drop pfn_valid_within() and simplify pfn_valid():
> https://lore.kernel.org/lkml/20210511100550.28178-5-rppt@kernel.org
> 
> arm64/mm: Drop HAVE_ARCH_PFN_VALID:
> https://lore.kernel.org/lkml/1621947349-25421-1-git-send-email-anshuman.khandual@arm.com

I dont see the above patch (which drops HAVE_ARCH_PFN_VALID on arm64) on linux-next
i.e. next-20210607. I might have missed some earlier context here but do not we want
to fallback on generic pfn_valid() after Mike's series ?