From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758904AbaIOVFb (ORCPT ); Mon, 15 Sep 2014 17:05:31 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:54669 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754960AbaIOT06 (ORCPT ); Mon, 15 Sep 2014 15:26:58 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Aneesh Kumar K.V" , Benjamin Herrenschmidt Subject: [PATCH 3.16 040/158] powerpc/thp: Add write barrier after updating the valid bit Date: Mon, 15 Sep 2014 12:24:39 -0700 Message-Id: <20140915192544.091648678@linuxfoundation.org> X-Mailer: git-send-email 2.1.0 In-Reply-To: <20140915192542.872134685@linuxfoundation.org> References: <20140915192542.872134685@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Aneesh Kumar K.V" commit b0aa44a3dfae3d8f45bd1264349aa87f87b7774f upstream. With hugepages, we store the hpte valid information in the pte page whose address is stored in the second half of the PMD. Use a write barrier to make sure clearing pmd busy bit and updating hpte valid info are ordered properly. Signed-off-by: Aneesh Kumar K.V Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/mm/hugepage-hash64.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/arch/powerpc/mm/hugepage-hash64.c +++ b/arch/powerpc/mm/hugepage-hash64.c @@ -172,8 +172,11 @@ repeat: mark_hpte_slot_valid(hpte_slot_array, index, slot); } /* - * No need to use ldarx/stdcx here + * The hpte valid is stored in the pgtable whose address is in the + * second half of the PMD. Order this against clearing of the busy bit in + * huge pmd. */ + smp_wmb(); *pmdp = __pmd(new_pmd & ~_PAGE_BUSY); return 0; }