From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7E77FC19F29 for ; Thu, 4 Aug 2022 02:08:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237123AbiHDCIn (ORCPT ); Wed, 3 Aug 2022 22:08:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40300 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229986AbiHDCIh (ORCPT ); Wed, 3 Aug 2022 22:08:37 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 44ECB5F13F for ; Wed, 3 Aug 2022 19:08:36 -0700 (PDT) Received: from canpemm500002.china.huawei.com (unknown [172.30.72.55]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4LysYb6ZGmzTgY3; Thu, 4 Aug 2022 10:07:15 +0800 (CST) Received: from [10.174.177.76] (10.174.177.76) by canpemm500002.china.huawei.com (7.192.104.244) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 4 Aug 2022 10:08:33 +0800 Subject: Re: [PATCH] mm, hwpoison, hugetlb: Free hwpoison huge page to list tail and dissolve hwpoison huge page first To: Mike Kravetz , luofei CC: Naoya Horiguchi , , , , References: <20220802100711.2425644-1-luofei@unicloud.com> From: Miaohe Lin Message-ID: <1191d45b-fece-659b-1dd1-8cf4ce89c2f1@huawei.com> Date: Thu, 4 Aug 2022 10:08:33 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.76] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To canpemm500002.china.huawei.com (7.192.104.244) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/8/3 0:58, Mike Kravetz wrote: > On 08/02/22 06:07, luofei wrote: >> If free hwpoison huge page to the end of hugepage_freelists, the >> loop can exit directly when the hwpoison huge page is traversed, >> which can effectively reduce the repeated traversal of the hwpoison >> huge page. Meanwhile, when free the free huge pages to lower level >> allocators, if hwpoison ones are released first, this can improve >> the effecvive utilization rate of huge page. > > In general, I think this is a good idea. Although, it seems that with > recent changes to hugetlb poisioning code we are even less likely to > have a poisioned page on hugetlb free lists. > > Adding Naoya and Miaohe as they have been looking at page poison of hugetlb > pages recently. > >> Signed-off-by: luofei >> --- >> mm/hugetlb.c | 13 ++++++++----- >> 1 file changed, 8 insertions(+), 5 deletions(-) >> >> diff --git a/mm/hugetlb.c b/mm/hugetlb.c >> index 28516881a1b2..ca72220eedd9 100644 >> --- a/mm/hugetlb.c >> +++ b/mm/hugetlb.c >> @@ -1116,7 +1116,10 @@ static void enqueue_huge_page(struct hstate *h, struct page *page) >> lockdep_assert_held(&hugetlb_lock); >> VM_BUG_ON_PAGE(page_count(page), page); >> >> - list_move(&page->lru, &h->hugepage_freelists[nid]); >> + if (unlikely(PageHWPoison(page))) >> + list_move_tail(&page->lru, &h->hugepage_freelists[nid]); >> + else >> + list_move(&page->lru, &h->hugepage_freelists[nid]); >> h->free_huge_pages++; >> h->free_huge_pages_node[nid]++; >> SetHPageFreed(page); >> @@ -1133,7 +1136,7 @@ static struct page *dequeue_huge_page_node_exact(struct hstate *h, int nid) >> continue; >> >> if (PageHWPoison(page)) >> - continue; >> + break; > > IIRC, it is 'possible' to unpoison a page via the debug/testing interfaces. > If so, then we could end up with free unpoisioned page(s) at the end of > the list that would never be used because we quit when encountering a > poisioned page. IIUC, above scene will actually happen. What's more, dissolve_free_huge_page might fail after hugetlb page is hwpoisoned due to e.g. all hugetlb pages are reserved. In that case, the hwpoisoned hugetlb page is not moved to the tail of hugepage_freelists and thus cause problems. Thanks both. > > Naoya and Miaohe would know for sure. > > Same possible issue in demote_pool_huge_page(). >