linux-kernel - Re: [PATCH] powerpc/mm: Make sure a local_irq

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Date:	Sat, 15 Mar 2014 15:25:30 -0400
From:	Rik van Riel <riel@...hat.com>
To:	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	benh@...nel.crashing.org, paulus@...ba.org
CC:	linuxppc-dev@...ts.ozlabs.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc/mm: Make sure a local_irq_disable prevent a parallel
 THP split

On 03/15/2014 06:47 AM, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
> 
> We have generic code like the one in get_futex_key that assume that
> a local_irq_disable prevents a parallel THP split. Support that by
> adding a dummy smp call function after setting _PAGE_SPLITTING. Code
> paths like get_user_pages_fast still need to check for _PAGE_SPLITTING
> after disabling IRQ which indicate that a parallel THP splitting is
> ongoing. Now if they don't find _PAGE_SPLITTING set, then we can be
> sure that parallel split will now block in pmdp_splitting flush
> until we enables IRQ
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@...ux.vnet.ibm.com>

Acked-by: Rik van Riel <riel@...hat.com>

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