From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755379AbcFQLSo (ORCPT ); Fri, 17 Jun 2016 07:18:44 -0400 Received: from szxga03-in.huawei.com ([119.145.14.66]:16868 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751301AbcFQLSl (ORCPT ); Fri, 17 Jun 2016 07:18:41 -0400 Message-ID: <5763DC85.8080707@huawei.com> Date: Fri, 17 Jun 2016 19:18:29 +0800 From: zhong jiang User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Michal Hocko CC: , , Subject: Re: [PATCH] mm: fix account pmd page to the process References: <1466076971-24609-1-git-send-email-zhongjiang@huawei.com> <20160616154214.GA12284@dhcp22.suse.cz> In-Reply-To: <20160616154214.GA12284@dhcp22.suse.cz> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.29.68] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020201.5763DC8C.0018,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-05-26 15:14:31, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 1054699614d72156453f71f17684c743 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016/6/16 23:42, Michal Hocko wrote: > 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? Yes, you are right. I will modify it in V2. Thanks zhongjiang > >> + >> spin_unlock(ptl); >> out: >> pte = (pte_t *)pmd_alloc(mm, pud, addr); >> -- >> 1.8.3.1