From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f70.google.com (mail-wm0-f70.google.com [74.125.82.70]) by kanga.kvack.org (Postfix) with ESMTP id 88FFC6B0279 for ; Wed, 24 May 2017 07:53:21 -0400 (EDT) Received: by mail-wm0-f70.google.com with SMTP id r203so37838833wmb.2 for ; Wed, 24 May 2017 04:53:21 -0700 (PDT) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id 31si18272015edq.171.2017.05.24.04.53.20 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 24 May 2017 04:53:20 -0700 (PDT) Subject: Re: [Question] Mlocked count will not be decreased References: <85591559-2a99-f46b-7a5a-bc7affb53285@huawei.com> <93f1b063-6288-d109-117d-d3c1cf152a8e@suse.cz> <5925709F.1030105@huawei.com> From: Vlastimil Babka Message-ID: Date: Wed, 24 May 2017 13:52:44 +0200 MIME-Version: 1.0 In-Reply-To: <5925709F.1030105@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Xishi Qiu Cc: Yisheng Xie , Kefeng Wang , linux-mm@kvack.org, linux-kernel@vger.kernel.org, zhongjiang On 05/24/2017 01:38 PM, Xishi Qiu wrote: >> >> Race condition with what? Who else would isolate our pages? >> > > Hi Vlastimil, > > I find the root cause, if the page was not cached on the current cpu, > lru_add_drain() will not push it to LRU. So we should handle fail > case in mlock_vma_page(). Yeah that would explain it. > follow_page_pte() > ... > if (page->mapping && trylock_page(page)) { > lru_add_drain(); /* push cached pages to LRU */ > /* > * Because we lock page here, and migration is > * blocked by the pte's page reference, and we > * know the page is still mapped, we don't even > * need to check for file-cache page truncation. > */ > mlock_vma_page(page); > unlock_page(page); > } > ... > > I think we should add yisheng's patch, also we should add the following change. > I think it is better than use lru_add_drain_all(). I agree about yisheng's fix (but v2 didn't address my comments). I don't think we should add the hunk below, as that deviates from the rest of the design. Thanks, Vlastimil > diff --git a/mm/mlock.c b/mm/mlock.c > index 3d3ee6c..ca2aeb9 100644 > --- a/mm/mlock.c > +++ b/mm/mlock.c > @@ -88,6 +88,11 @@ void mlock_vma_page(struct page *page) > count_vm_event(UNEVICTABLE_PGMLOCKED); > if (!isolate_lru_page(page)) > putback_lru_page(page); > + else { > + ClearPageMlocked(page); > + mod_zone_page_state(page_zone(page), NR_MLOCK, > + -hpage_nr_pages(page)); > + } > } > } > > Thanks, > Xishi Qiu > -- 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