Date: Fri, 16 Dec 2016 18:14:06 +0100
From: Robert Richter <robert.richter@cavium.com>
To: Hanjun Guo <hanjun.guo@linaro.org>
CC: Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        <linux-arm-kernel@lists.infradead.org>, <will.deacon@arm.com>,
        <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
        <catalin.marinas@arm.com>, <akpm@linux-foundation.org>,
        <xieyisheng1@huawei.com>, <james.morse@arm.com>
Subject: Re: [PATCH 2/2] arm64: mm: enable CONFIG_HOLES_IN_ZONE for NUMA
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On 16.12.16 09:57:20, Hanjun Guo wrote:
> Hi Robert,
> 
> On 2016/12/15 23:39, Robert Richter wrote:
> >I was going to do some measurements but my kernel crashes now with a
> >page fault in efi_rtc_probe():
> >
> >[   21.663393] Unable to handle kernel paging request at virtual address 20251000
> >[   21.663396] pgd = ffff000009090000
> >[   21.663401] [20251000] *pgd=0000010ffff90003
> >[   21.663402] , *pud=0000010ffff90003
> >[   21.663404] , *pmd=0000000fdc030003
> >[   21.663405] , *pte=00e8832000250707
> >
> >The sparsemem config requires the whole section to be initialized.
> >Your patches do not address this.
> 
> This patch set is running properly on D05, both the boot and
> LTP MM stress test are ok, seems it's a different configuration
> of memory mappings in firmware, just a stupid question, which
> part is related to this problem, is it only the Reserved memory?

The problem are efi reserved regions that are no longer reserved but
marked as nomap pages. Those are excluded from page initialization
causing parts of a memory section not being initialized.

-Robert