From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f197.google.com (mail-pf0-f197.google.com [209.85.192.197]) by kanga.kvack.org (Postfix) with ESMTP id 03F506B026C for ; Mon, 30 Jan 2017 10:16:25 -0500 (EST) Received: by mail-pf0-f197.google.com with SMTP id d123so204231734pfd.0 for ; Mon, 30 Jan 2017 07:16:24 -0800 (PST) Received: from smtpbg298.qq.com (smtpbg298.qq.com. [184.105.67.102]) by mx.google.com with ESMTPS id v187si8680294pgv.219.2017.01.30.07.16.23 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 30 Jan 2017 07:16:24 -0800 (PST) Subject: Re: [RFC v2 PATCH] mm/hotplug: enable memory hotplug for non-lru movable pages References: <1485327585-62872-1-git-send-email-xieyisheng1@huawei.com> <20170126094303.GE6590@dhcp22.suse.cz> From: Yisheng Xie Message-ID: <588F584F.5080904@foxmail.com> Date: Mon, 30 Jan 2017 23:14:23 +0800 MIME-Version: 1.0 In-Reply-To: <20170126094303.GE6590@dhcp22.suse.cz> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko , Yisheng Xie Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, vbabka@suse.cz, mgorman@techsingularity.net, hannes@cmpxchg.org, iamjoonsoo.kim@lge.com, izumi.taku@jp.fujitsu.com, arbab@linux.vnet.ibm.com, vkuznets@redhat.com, ak@linux.intel.com, n-horiguchi@ah.jp.nec.com, minchan@kernel.org, qiuxishi@huawei.com, guohanjun@huawei.com hi Michal, Thank you for reviewing and sorry for late reply. On 01/26/2017 05:43 PM, Michal Hocko wrote: > On Wed 25-01-17 14:59:45, Yisheng Xie wrote: > > static unsigned long scan_movable_pages(unsigned long start, unsigned long end) > { > @@ -1531,6 +1531,16 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end) > pfn = round_up(pfn + 1, > 1 << compound_order(page)) - 1; > } > + /* > + * check __PageMovable in lock_page to avoid miss some > + * non-lru movable pages at race condition. > + */ > + lock_page(page); > + if (__PageMovable(page)) { > + unlock_page(page); > + return pfn; > + } > + unlock_page(page); > This doesn't make any sense to me. __PageMovable can change right after > you drop the lock so why the race matters? If we cannot tolerate races > then the above doesn't work and if we can then taking the lock is > pointless. hmm, for PageLRU check may also race without lru-locki 1/4 ? I think it is ok to check __PageMovable without lock_page, here. >> } >> } >> return 0; >> @@ -1600,21 +1610,25 @@ static struct page *new_node_page(struct page *page, unsigned long private, >> if (!get_page_unless_zero(page)) >> continue; >> /* >> - * We can skip free pages. And we can only deal with pages on >> - * LRU. >> + * We can skip free pages. And we can deal with pages on >> + * LRU and non-lru movable pages. >> */ >> - ret = isolate_lru_page(page); >> + if (PageLRU(page)) >> + ret = isolate_lru_page(page); >> + else >> + ret = !isolate_movable_page(page, ISOLATE_UNEVICTABLE); > we really want to propagate the proper error code to the caller. Yes , I make the same mistake again. Really sorry about that. Maybe I can rewrite the isolate_movable_page to let it return int as isolate_lru_page do in this patchset :) Thanks Yisheng Xie -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753747AbdA3PYm (ORCPT ); Mon, 30 Jan 2017 10:24:42 -0500 Received: from smtpbg298.qq.com ([184.105.67.102]:46811 "EHLO smtpbg298.qq.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753722AbdA3PYH (ORCPT ); Mon, 30 Jan 2017 10:24:07 -0500 X-Greylist: delayed 372 seconds by postgrey-1.27 at vger.kernel.org; Mon, 30 Jan 2017 10:24:07 EST X-QQ-mid: esmtp12t1485789267ta25q90nl X-QQ-SSF: 01000000000000606G110300000000V X-QQ-FEAT: JibMalLukFb1k8I3hGF8UgOmt8sXRuboHXoZrKlVH2n/0/VQt6o+lpqkv6Pfq mP/5ssiqsyTKptPL1SgDalvxobbC3C45BcnJFsjk4cxRL6SZmoQvgJ79o48H3XE6UtJmmBT pNJkOc9G0j+4UuHYM2e60JPqz9GQeF9hzrTSC+6HTy9c5++CIn8s2Im0P+qK31sGncXXsNa qWd2tvvZVgWoUtyejcX0KRJ9e0RZB8Udhh08Iix22yi1ySzV0B4WNlklpbZNiYVGzAVvBwW TApQ== X-QQ-GoodBg: 0 Subject: Re: [RFC v2 PATCH] mm/hotplug: enable memory hotplug for non-lru movable pages To: Michal Hocko , Yisheng Xie References: <1485327585-62872-1-git-send-email-xieyisheng1@huawei.com> <20170126094303.GE6590@dhcp22.suse.cz> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, vbabka@suse.cz, mgorman@techsingularity.net, hannes@cmpxchg.org, iamjoonsoo.kim@lge.com, izumi.taku@jp.fujitsu.com, arbab@linux.vnet.ibm.com, vkuznets@redhat.com, ak@linux.intel.com, n-horiguchi@ah.jp.nec.com, minchan@kernel.org, qiuxishi@huawei.com, guohanjun@huawei.com From: Yisheng Xie Message-ID: <588F584F.5080904@foxmail.com> Date: Mon, 30 Jan 2017 23:14:23 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <20170126094303.GE6590@dhcp22.suse.cz> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-QQ-SENDSIZE: 520 X-QQ-FName: 9AA197F417F747CABE8D105E4528919D X-QQ-LocalIP: 10.198.131.167 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org hi Michal, Thank you for reviewing and sorry for late reply. On 01/26/2017 05:43 PM, Michal Hocko wrote: > On Wed 25-01-17 14:59:45, Yisheng Xie wrote: > > static unsigned long scan_movable_pages(unsigned long start, unsigned long end) > { > @@ -1531,6 +1531,16 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end) > pfn = round_up(pfn + 1, > 1 << compound_order(page)) - 1; > } > + /* > + * check __PageMovable in lock_page to avoid miss some > + * non-lru movable pages at race condition. > + */ > + lock_page(page); > + if (__PageMovable(page)) { > + unlock_page(page); > + return pfn; > + } > + unlock_page(page); > This doesn't make any sense to me. __PageMovable can change right after > you drop the lock so why the race matters? If we cannot tolerate races > then the above doesn't work and if we can then taking the lock is > pointless. hmm, for PageLRU check may also race without lru-lockļ¼Œ I think it is ok to check __PageMovable without lock_page, here. >> } >> } >> return 0; >> @@ -1600,21 +1610,25 @@ static struct page *new_node_page(struct page *page, unsigned long private, >> if (!get_page_unless_zero(page)) >> continue; >> /* >> - * We can skip free pages. And we can only deal with pages on >> - * LRU. >> + * We can skip free pages. And we can deal with pages on >> + * LRU and non-lru movable pages. >> */ >> - ret = isolate_lru_page(page); >> + if (PageLRU(page)) >> + ret = isolate_lru_page(page); >> + else >> + ret = !isolate_movable_page(page, ISOLATE_UNEVICTABLE); > we really want to propagate the proper error code to the caller. Yes , I make the same mistake again. Really sorry about that. Maybe I can rewrite the isolate_movable_page to let it return int as isolate_lru_page do in this patchset :) Thanks Yisheng Xie