From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by ozlabs.org (Postfix) with ESMTP id E1AE32C00AE for ; Sun, 16 Mar 2014 06:25:42 +1100 (EST) Message-ID: <5324A92A.3040309@redhat.com> Date: Sat, 15 Mar 2014 15:25:30 -0400 From: Rik van Riel MIME-Version: 1.0 To: "Aneesh Kumar K.V" , benh@kernel.crashing.org, paulus@samba.org Subject: Re: [PATCH] powerpc/mm: Make sure a local_irq_disable prevent a parallel THP split References: <1394880478-770-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> In-Reply-To: <1394880478-770-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Content-Type: text/plain; charset=UTF-8 Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 03/15/2014 06:47 AM, Aneesh Kumar K.V wrote: > From: "Aneesh Kumar K.V" > > 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 Acked-by: Rik van Riel -- All rights reversed