linux-kernel - Re: Arm64 crash while reading memory sysfs

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Date:   Thu, 27 May 2021 19:12:10 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Mike Rapoport <rppt@...ux.ibm.com>,
        Qian Cai <quic_qiancai@...cinc.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: Arm64 crash while reading memory sysfs

>> [  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