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Fri, 30 Apr 2021 17:43:30 +0800 (CST) Subject: Re: [RFC PATCH] mm/page_alloc: fix counting of free pages after take off from buddy To: David Hildenbrand , akpm@linux-foundation.org, naoya.horiguchi@nec.com, osalvador@suse.de Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20210421020426.5914-1-dinghui@sangfor.com.cn> From: Ding Hui Message-ID: <8cd355d2-1adc-4189-7b65-cfea13129db5@sangfor.com.cn> Date: Fri, 30 Apr 2021 17:43:40 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US X-HM-Spam-Status: e1kfGhgUHx5ZQUtXWQgYFAkeWUFZS1VLWVdZKFlBSE83V1ktWUFJV1kPCR oVCBIfWUFZGU1LHlZDSEgeS0xDS0gfQxpVEwETFhoSFyQUDg9ZV1kWGg8SFR0UWUFZT0tIVUpKS0 9ISVVLWQY+ X-HM-Sender-Digest: e1kMHhlZQR0aFwgeV1kSHx4VD1lBWUc6KyI6ERw5IT8WOE9CMAgxDyg* MzcKChdVSlVKTUpCTExOQ0pKSk1KVTMWGhIXVR8SFRwTDhI7CBoVHB0UCVUYFBZVGBVFWVdZEgtZ QVlKT1VKTk9VSEtVSEJZV1kIAVlBSUNPSDcG X-HM-Tid: 0a7922296d45b037kuuu9d1e3800c9 Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 8E72F2000381 Authentication-Results: imf11.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=sangfor.com.cn; spf=pass (imf11.hostedemail.com: domain of dinghui@sangfor.com.cn designates 115.236.121.142 as permitted sender) smtp.mailfrom=dinghui@sangfor.com.cn X-Stat-Signature: hp9hg1s1fojtrk5pmfpi4fcer16shisg Received-SPF: none (sangfor.com.cn>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=mail-m121142.qiye.163.com; client-ip=115.236.121.142 X-HE-DKIM-Result: none/none X-HE-Tag: 1619775798-340136 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2021/4/28 22:54, David Hildenbrand wrote: > On 21.04.21 04:04, Ding Hui wrote: >> Recently we found there is a lot MemFree left in /proc/meminfo after >> do a lot of pages soft offline. >> >> I think it's incorrect since NR_FREE_PAGES should not contain HWPoison= =20 >> pages. >> After take_page_off_buddy, the page is no longer belong to buddy >> allocator, and will not be used any more, but we maybe missed accounti= ng >> NR_FREE_PAGES in this situation. >> >> Signed-off-by: Ding Hui >> --- >> =C2=A0 mm/page_alloc.c | 1 + >> =C2=A0 1 file changed, 1 insertion(+) >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index cfc72873961d..8d65b62784d8 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -8947,6 +8947,7 @@ bool take_page_off_buddy(struct page *page) >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 del_page_from_free_list(page_head, zone, page_order); >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 break_down_buddy_pages(zone, page_head, page, 0, >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2= =A0 page_order, migratetype); >> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 __= mod_zone_page_state(zone, NR_FREE_PAGES, -1); >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 ret =3D true; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0 break; >> =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } >> >=20 > Should this use __mod_zone_freepage_state() instead? >=20 Yes, you're right. I'll use it in v2. --=20 Thanks, - Ding Hui