From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756148AbaCOKsX (ORCPT ); Sat, 15 Mar 2014 06:48:23 -0400 Received: from e28smtp03.in.ibm.com ([122.248.162.3]:34937 "EHLO e28smtp03.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755951AbaCOKsV (ORCPT ); Sat, 15 Mar 2014 06:48:21 -0400 From: "Aneesh Kumar K.V" To: benh@kernel.crashing.org, paulus@samba.org, Rik van Riel Cc: linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Aneesh Kumar K.V" Subject: [PATCH] powerpc/mm: Make sure a local_irq_disable prevent a parallel THP split Date: Sat, 15 Mar 2014 16:17:58 +0530 Message-Id: <1394880478-770-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> X-Mailer: git-send-email 1.8.3.2 X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14031510-3864-0000-0000-00000CFAA251 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- arch/powerpc/mm/pgtable_64.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c index 62bf5e8e78da..f6ce1f111f5b 100644 --- a/arch/powerpc/mm/pgtable_64.c +++ b/arch/powerpc/mm/pgtable_64.c @@ -647,6 +647,11 @@ void pmdp_splitting_flush(struct vm_area_struct *vma, if (old & _PAGE_HASHPTE) hpte_do_hugepage_flush(vma->vm_mm, address, pmdp); } + /* + * This ensures that generic code that rely on IRQ disabling + * to prevent a parallel THP split work as expected. + */ + kick_all_cpus_sync(); } /* -- 1.8.3.2