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Subject: Re: Arm64 crash while reading memory sysfs
To:     Mike Rapoport <rppt@linux.ibm.com>,
        Qian Cai <quic_qiancai@quicinc.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Anshuman Khandual <anshuman.khandual@arm.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:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
Message-ID: <3a5fa459-cd00-8a65-3ee1-debc51424a7c@redhat.com>
Date:   Thu, 27 May 2021 19:12:10 +0200
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>> [  259.216661][ T1417] test_pages_in_a_zone: pfn 8000 is not valid
>> [  259.226547][ T1417] page:00000000f4aa8c5c is uninitialized and poisoned
>> [  259.226560][ T1417] page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p))
> 
> 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.
> 

Oh, that makes sense to me.

-- 
Thanks,

David / dhildenb