From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S939302AbdEXI6Z (ORCPT ); Wed, 24 May 2017 04:58:25 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:6892 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S939285AbdEXI6J (ORCPT ); Wed, 24 May 2017 04:58:09 -0400 Subject: Re: [Question] Mlocked count will not be decreased To: Yisheng Xie , , , zhongjiang , Qiuxishi , Tetsuo Handa References: <85591559-2a99-f46b-7a5a-bc7affb53285@huawei.com> CC: Vlastimil Babka , Minchan Kim , "Kirill A. Shutemov" , Andrew Morton From: Kefeng Wang Message-ID: Date: Wed, 24 May 2017 16:57:58 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.1.0 MIME-Version: 1.0 In-Reply-To: <85591559-2a99-f46b-7a5a-bc7affb53285@huawei.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.177.19.180] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A0B0201.59254B1E.0187,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2014-11-16 11:51:01, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: 2a645ed076d288b5baea6f72ba48e7eb Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2017/5/24 16:32, Yisheng Xie wrote: > Hi Kefengļ¼Œ > Could you please try this patch. It works for me, thanks. Kefeng. > > Thanks > Yisheng Xie > ------------- >>>From a70ae975756e8e97a28d49117ab25684da631689 Mon Sep 17 00:00:00 2001 > From: Yisheng Xie > Date: Wed, 24 May 2017 16:01:24 +0800 > Subject: [PATCH] mlock: fix mlock count can not decrease in race condition > > Kefeng reported that when run the follow test the mlock count in meminfo > cannot be decreased: > [1] testcase > linux:~ # cat test_mlockal > grep Mlocked /proc/meminfo > for j in `seq 0 10` > do > for i in `seq 4 15` > do > ./p_mlockall >> log & > done > sleep 0.2 > done > sleep 5 # wait some time to let mlock decrease > grep Mlocked /proc/meminfo > > linux:~ # cat p_mlockall.c > #include > #include > #include > > #define SPACE_LEN 4096 > > int main(int argc, char ** argv) > { > int ret; > void *adr = malloc(SPACE_LEN); > if (!adr) > return -1; > > ret = mlockall(MCL_CURRENT | MCL_FUTURE); > printf("mlcokall ret = %d\n", ret); > > ret = munlockall(); > printf("munlcokall ret = %d\n", ret); > > free(adr); > return 0; > } > > When __munlock_pagevec, we ClearPageMlock but isolation_failed in race > condition, and we do not count these page into delta_munlocked, which cause mlock > counter incorrect for we had Clear the PageMlock and cannot count down > the number in the feture. > > Fix it by count the number of page whoes PageMlock flag is cleared. > > Reported-by: Kefeng Wang > Signed-off-by: Yisheng Xie > --- > mm/mlock.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/mm/mlock.c b/mm/mlock.c > index c483c5c..71ba5cf 100644 > --- a/mm/mlock.c > +++ b/mm/mlock.c > @@ -284,7 +284,7 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone) > { > int i; > int nr = pagevec_count(pvec); > - int delta_munlocked; > + int munlocked = 0; > struct pagevec pvec_putback; > int pgrescued = 0; > > @@ -296,6 +296,7 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone) > struct page *page = pvec->pages[i]; > > if (TestClearPageMlocked(page)) { > + munlocked --; > /* > * We already have pin from follow_page_mask() > * so we can spare the get_page() here. > @@ -315,8 +316,8 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone) > pagevec_add(&pvec_putback, pvec->pages[i]); > pvec->pages[i] = NULL; > } > - delta_munlocked = -nr + pagevec_count(&pvec_putback); > - __mod_zone_page_state(zone, NR_MLOCK, delta_munlocked); > + if (munlocked) > + __mod_zone_page_state(zone, NR_MLOCK, munlocked); > spin_unlock_irq(zone_lru_lock(zone)); > > /* Now we can release pins of pages that we are not munlocking */ >