linux-kernel - Re: [PATCH] arm: Update memblock limit after mapping lowmem

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Date:	Wed, 24 Jun 2015 17:07:27 -0700
From:	Laura Abbott <labbott@...hat.com>
To:	Mark Rutland <mark.rutland@....com>,
	Laura Abbott <labbott@...oraproject.org>
CC:	Russell King <linux@....linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>, Nicolas Pitre <nico@...aro.org>,
	Stefan Agner <stefan@...er.ch>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Will Deacon <Will.Deacon@....com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Hans de Goede <hdegoede@...hat.com>
Subject: Re: [PATCH] arm: Update memblock limit after mapping lowmem

On 06/11/2015 06:07 AM, Mark Rutland wrote:
> On Thu, Jun 04, 2015 at 08:15:49PM +0100, Laura Abbott wrote:
>>
>> The memblock limit is currently used in find_limits
>> to find the bounds for ZONE_NORMAL. The memblock
>> limit may need to be rounded down a PMD size to ensure
>> allocations are fully mapped though. This has the side
>> effect of reducing the amount of memory in ZONE_NORMAL.
>> Once all lowmem is mapped, it's safe to change the memblock
>> limit back to include the unaligned section. Adjust the
>> memblock limit after lowmem mapping is complete.
>>
>> Before:
>>   # cat /proc/zoneinfo | grep managed
>>          managed  62907
>>          managed  424
>>
>> After:
>>   # cat /proc/zoneinfo | grep managed
>>          managed  63331
>>
>> Signed-off-by: Laura Abbott <labbott@...oraproject.org>
>> ---
>> This is a replacement for
>> 'arm: Don't use memblock limit for the lowmem bound' which
>> doesn't actually work on NOMMU systems.
>
> Works for me on TC2, atop v4.1-rc7. Before this patch, with a few byes
> carved out of the memory node I would see:
>
> Memory: 1030380K/1046528K available (4832K kernel code, 154K rwdata, 1376K rodata, 260K init, 147K bss, 16148K reserved, 0K cma-reserved)
>
> $ cat /proc/zoneinfo | grep managed
>          managed  257660
>
> With the patch I see:
>
> Memory: 1032424K/1048572K available (4832K kernel code, 154K rwdata, 1376K rodata, 260K init, 147K bss, 16148K reserved, 0K cma-reserved)
>
> $ cat /proc/zoneinfo | grep managed
>          managed  258171
>
> The patch itself looks good to me.
>
> Reviewed-by: Mark Rutland <mark.rutland@....com>
> Tested-by: Mark Rutland <mark.rutland@....com>
>
> Thanks,
> Mark.
>

FYI, I put this in the patch tracker. I was on vacation when the Reviewed-by/Tested-by
came in so I'm only getting to it now.

Thanks,
Laura

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