From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vk0-f70.google.com (mail-vk0-f70.google.com [209.85.213.70]) by kanga.kvack.org (Postfix) with ESMTP id 6C1386B0389 for ; Thu, 23 Feb 2017 11:26:43 -0500 (EST) Received: by mail-vk0-f70.google.com with SMTP id x75so27314077vke.5 for ; Thu, 23 Feb 2017 08:26:43 -0800 (PST) Received: from mx0a-00082601.pphosted.com (mx0b-00082601.pphosted.com. [67.231.153.30]) by mx.google.com with ESMTPS id u197si1393101vkb.66.2017.02.23.08.26.42 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 23 Feb 2017 08:26:42 -0800 (PST) Date: Thu, 23 Feb 2017 08:26:03 -0800 From: Shaohua Li Subject: Re: [PATCH V4 3/6] mm: move MADV_FREE pages into LRU_INACTIVE_FILE list Message-ID: <20170223162601.GA18526@brenorobert-mbp.dhcp.thefacebook.com> References: <20170223155827.GB4031@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20170223155827.GB4031@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kernel-team@fb.com, mhocko@suse.com, minchan@kernel.org, hughd@google.com, riel@redhat.com, mgorman@techsingularity.net, akpm@linux-foundation.org On Thu, Feb 23, 2017 at 10:58:27AM -0500, Johannes Weiner wrote: > Hi Shaohua, > > On Wed, Feb 22, 2017 at 10:50:41AM -0800, Shaohua Li wrote: > > @@ -268,6 +268,12 @@ static void __activate_page(struct page *page, struct lruvec *lruvec, > > int lru = page_lru_base_type(page); > > > > del_page_from_lru_list(page, lruvec, lru); > > + if (PageAnon(page) && !PageSwapBacked(page)) { > > + SetPageSwapBacked(page); > > + /* charge to anon scanned/rotated reclaim_stat */ > > + file = 0; > > + lru = LRU_INACTIVE_ANON; > > + } > > As per my previous feedback, please remove this. Write-after-free will > be caught and handled in the reclaimer, read-after-free is a bug that > really doesn't require optimizing page aging for. And we definitely > shouldn't declare invalid data suddenly valid because it's being read. GUP could run into this. Don't we move the page because it's hot? I think it's not just about page aging. If we leave the page there, page reclaim will just waste time to reclaim the pages which should't be reclaimed. Thanks, Shaohua -- 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