linux-kernel - Re: [PATCH] x86/efi: Only pass mapped RAM regions to free_bootmem

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Date:	Thu, 5 Jun 2014 19:07:50 +0100
From:	Matt Fleming <matt@...sole-pimps.org>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	linux-efi@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	Matt Fleming <matt.fleming@...el.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Dave Hansen <dave.hansen@...el.com>,
	Borislav Petkov <bp@...e.de>
Subject: Re: [PATCH] x86/efi: Only pass mapped RAM regions to free_bootmem_late()

On 5 June 2014 16:01, Alan Cox <alan@...rguk.ukuu.org.uk> wrote:
> On Thu,  5 Jun 2014 14:27:34 +0100
> Matt Fleming <matt@...sole-pimps.org> wrote:
>
>> From: Matt Fleming <matt.fleming@...el.com>
>>
>> free_bootmem_late() expects to only be passed RAM regions that the
>> kernel can access, and that have a corresponding 'struct page'. It's
>> possible for regions in the EFI memory map to reside in address ranges
>> for which pfn_to_page() doesn't work, for instance when running on an
>> i386 system with CONFIG_HIGHMEM=n.
>>
>> This is in fact the case for one of Alan's machines where some of the
>> EFI boot services pages live in highmem, and running a kernel without
>> CONFIG_HIGHMEM enabled results in the following oops,
>>
>>  BUG: unable to handle kernel paging request at f7f1f080
>>  IP: [<c17fba96>] __free_pages_bootmem+0x5a/0xb8
>>  *pdpt = 0000000001887001 *pde = 0000000001984067 *pte = 000000000 0000000
>>  Oops: 0002 [#1] SMP
>
> No improvement, and the if case is never true 8(

Argh, dammit. OK, back to the drawing board. Thanks for testing.
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