From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753245AbdFVKyV (ORCPT ); Thu, 22 Jun 2017 06:54:21 -0400 Received: from mail-qt0-f194.google.com ([209.85.216.194]:35788 "EHLO mail-qt0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752934AbdFVKyT (ORCPT ); Thu, 22 Jun 2017 06:54:19 -0400 MIME-Version: 1.0 In-Reply-To: <1498081816-179369-1-git-send-email-nitin.m.gupta@oracle.com> References: <1498081816-179369-1-git-send-email-nitin.m.gupta@oracle.com> From: Julian Calaby Date: Thu, 22 Jun 2017 20:53:57 +1000 Message-ID: Subject: Re: [PATCH] sparc64: Fix gup_huge_pmd To: Nitin Gupta Cc: "David S. Miller" , Lorenzo Stoakes , Jan Kara , Michal Hocko , sparclinux , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Nitin, On Thu, Jun 22, 2017 at 7:50 AM, Nitin Gupta wrote: > The function assumes that each PMD points to head of a > huge page. This is not correct as a PMD can point to > start of any 8M region with a, say 256M, hugepage. The > fix ensures that it points to the correct head of any PMD > huge page. > > Signed-off-by: Nitin Gupta > --- > arch/sparc/mm/gup.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c > index cd0e32b..9116a6f 100644 > --- a/arch/sparc/mm/gup.c > +++ b/arch/sparc/mm/gup.c > @@ -80,6 +80,8 @@ static int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr, > refs = 0; > head = pmd_page(pmd); > page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT); > + if (PageTail(head)) > + head = compound_head(head); Stupid question: shouldn't this go before the page calculation? > do { > VM_BUG_ON(compound_head(page) != head); > pages[*nr] = page; Thanks, -- Julian Calaby Email: julian.calaby@gmail.com Profile: http://www.google.com/profiles/julian.calaby/ From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julian Calaby Date: Thu, 22 Jun 2017 10:53:57 +0000 Subject: Re: [PATCH] sparc64: Fix gup_huge_pmd Message-Id: List-Id: References: <1498081816-179369-1-git-send-email-nitin.m.gupta@oracle.com> In-Reply-To: <1498081816-179369-1-git-send-email-nitin.m.gupta@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Nitin Gupta Cc: "David S. Miller" , Lorenzo Stoakes , Jan Kara , Michal Hocko , sparclinux , "linux-kernel@vger.kernel.org" Hi Nitin, On Thu, Jun 22, 2017 at 7:50 AM, Nitin Gupta wrote: > The function assumes that each PMD points to head of a > huge page. This is not correct as a PMD can point to > start of any 8M region with a, say 256M, hugepage. The > fix ensures that it points to the correct head of any PMD > huge page. > > Signed-off-by: Nitin Gupta > --- > arch/sparc/mm/gup.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c > index cd0e32b..9116a6f 100644 > --- a/arch/sparc/mm/gup.c > +++ b/arch/sparc/mm/gup.c > @@ -80,6 +80,8 @@ static int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr, > refs = 0; > head = pmd_page(pmd); > page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT); > + if (PageTail(head)) > + head = compound_head(head); Stupid question: shouldn't this go before the page calculation? > do { > VM_BUG_ON(compound_head(page) != head); > pages[*nr] = page; Thanks, -- Julian Calaby Email: julian.calaby@gmail.com Profile: http://www.google.com/profiles/julian.calaby/