From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754388AbcFPPmT (ORCPT ); Thu, 16 Jun 2016 11:42:19 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:33038 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753846AbcFPPmS (ORCPT ); Thu, 16 Jun 2016 11:42:18 -0400 Date: Thu, 16 Jun 2016 17:42:15 +0200 From: Michal Hocko To: zhongjiang Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: fix account pmd page to the process Message-ID: <20160616154214.GA12284@dhcp22.suse.cz> References: <1466076971-24609-1-git-send-email-zhongjiang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1466076971-24609-1-git-send-email-zhongjiang@huawei.com> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 16-06-16 19:36:11, zhongjiang wrote: > From: zhong jiang > > when a process acquire a pmd table shared by other process, we > increase the account to current process. otherwise, a race result > in other tasks have set the pud entry. so it no need to increase it. > > Signed-off-by: zhong jiang > --- > mm/hugetlb.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 19d0d08..3b025c5 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -4189,10 +4189,9 @@ pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud) > if (pud_none(*pud)) { > pud_populate(mm, pud, > (pmd_t *)((unsigned long)spte & PAGE_MASK)); > - } else { > + } else > put_page(virt_to_page(spte)); > - mm_inc_nr_pmds(mm); > - } The code is quite puzzling but is this correct? Shouldn't we rather do mm_dec_nr_pmds(mm) in that path to undo the previous inc? > + > spin_unlock(ptl); > out: > pte = (pte_t *)pmd_alloc(mm, pud, addr); > -- > 1.8.3.1 -- Michal Hocko SUSE Labs From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id C169D6B0005 for ; Thu, 16 Jun 2016 11:42:18 -0400 (EDT) Received: by mail-wm0-f72.google.com with SMTP id k184so29291214wme.3 for ; Thu, 16 Jun 2016 08:42:18 -0700 (PDT) Received: from mail-wm0-f67.google.com (mail-wm0-f67.google.com. [74.125.82.67]) by mx.google.com with ESMTPS id y75si1035289wmc.75.2016.06.16.08.42.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 16 Jun 2016 08:42:17 -0700 (PDT) Received: by mail-wm0-f67.google.com with SMTP id r5so12450514wmr.0 for ; Thu, 16 Jun 2016 08:42:17 -0700 (PDT) Date: Thu, 16 Jun 2016 17:42:15 +0200 From: Michal Hocko Subject: Re: [PATCH] mm: fix account pmd page to the process Message-ID: <20160616154214.GA12284@dhcp22.suse.cz> References: <1466076971-24609-1-git-send-email-zhongjiang@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1466076971-24609-1-git-send-email-zhongjiang@huawei.com> Sender: owner-linux-mm@kvack.org List-ID: To: zhongjiang Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu 16-06-16 19:36:11, zhongjiang wrote: > From: zhong jiang > > when a process acquire a pmd table shared by other process, we > increase the account to current process. otherwise, a race result > in other tasks have set the pud entry. so it no need to increase it. > > Signed-off-by: zhong jiang > --- > mm/hugetlb.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 19d0d08..3b025c5 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -4189,10 +4189,9 @@ pte_t *huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud) > if (pud_none(*pud)) { > pud_populate(mm, pud, > (pmd_t *)((unsigned long)spte & PAGE_MASK)); > - } else { > + } else > put_page(virt_to_page(spte)); > - mm_inc_nr_pmds(mm); > - } The code is quite puzzling but is this correct? Shouldn't we rather do mm_dec_nr_pmds(mm) in that path to undo the previous inc? > + > spin_unlock(ptl); > out: > pte = (pte_t *)pmd_alloc(mm, pud, addr); > -- > 1.8.3.1 -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org