linux-kernel - Re: [PATCH] ARM: mm: Fix the memblock allocation for LPAE machines

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Date:	Wed, 5 Feb 2014 19:50:55 -0500
From:	Santosh Shilimkar <santosh.shilimkar@...com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, Yinghai Lu <yinghai@...nel.org>,
	"Strashko, Grygorii" <grygorii.strashko@...com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] ARM: mm: Fix the memblock allocation for LPAE machines

On Wednesday 05 February 2014 06:48 PM, Russell King - ARM Linux wrote:
> On Wed, Feb 05, 2014 at 06:39:44PM -0500, Santosh Shilimkar wrote:
>> Russell,
>>
>> On Saturday 01 February 2014 03:14 PM, Santosh Shilimkar wrote:
>>> Commit ad6492b8 added much needed memblock_virt_alloc_low() and further
>>> commit 07bacb3 {memblock, bootmem: restore goal for alloc_low} fixed the
>>> issue with low memory limit thansk to Yinghai. But even after all these fixes,
>>> there is still one case where the limit check done with ARCH_LOW_ADDRESS_LIMIT
>>> for low memory fails. Russell pointed out the issue with 32 bit LPAE machines
>>> in below thread.
>>> 	https://lkml.org/lkml/2014/1/28/364
>>>
>>> Since on some LPAE machines where memory start address is beyond 4GB,
>>> the low memory marker in memblock will be set to default
>>> ARCH_LOW_ADDRESS_LIMIT which is wrong. We can fix this by letting
>>> architectures set the ARCH_LOW_ADDRESS_LIMIT using another export
>>> similar to memblock_set_current_limit() but am not sure whether
>>> its worth the trouble. Tell me if you think otherwise.
>>>
>>> Rather am just trying to fix that one broken case using memblock_virt_alloc()
>>> in setup code since the memblock.current_limit is updated appropriately
>>> makes it work on all ARM 32 bit machines.
>>>
>>> Cc: Yinghai Lu <yinghai@...nel.org>
>>> Cc: Russell King <linux@....linux.org.uk>
>>> Cc: Strashko, Grygorii <grygorii.strashko@...com>
>>> Cc: Andrew Morton <akpm@...ux-foundation.org>
>>> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@...com>
>>> ---
>> Whats you say here ? We should get the fix for the
>> issue. If you are ok, I can drop the patch in patch system.
> 
> Is this still an issue, or has Tejun fixed it by some other means?  I've not
> noticed anything being broken at the moment.
> 
> Can you confirm whether we still have an issue without this patch please?
> 
Fixes for all cases exist except 'LPAE + memory start beyond 4 GB'.
This case is still broken and  hence I posted the $subject patch.

Regards,
Santosh

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