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 X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4CBEC433E1 for ; Tue, 30 Mar 2021 02:10:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7FF6B617C9 for ; Tue, 30 Mar 2021 02:10:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230434AbhC3CK1 (ORCPT ); Mon, 29 Mar 2021 22:10:27 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:15095 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230089AbhC3CKS (ORCPT ); Mon, 29 Mar 2021 22:10:18 -0400 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4F8Xsd1l1Dz17PBQ; Tue, 30 Mar 2021 10:08:05 +0800 (CST) Received: from [10.174.179.86] (10.174.179.86) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.498.0; Tue, 30 Mar 2021 10:10:03 +0800 Subject: Re: [PATCH v2 5/8] hugetlb: call update_and_free_page without hugetlb_lock To: Mike Kravetz , , CC: Roman Gushchin , Michal Hocko , Shakeel Butt , Oscar Salvador , David Hildenbrand , Muchun Song , David Rientjes , Peter Zijlstra , Matthew Wilcox , HORIGUCHI NAOYA , "Aneesh Kumar K . V" , Waiman Long , Peter Xu , Mina Almasry , "Hillf Danton" , Joonsoo Kim , Barry Song , Will Deacon , Andrew Morton References: <20210329232402.575396-1-mike.kravetz@oracle.com> <20210329232402.575396-6-mike.kravetz@oracle.com> From: Miaohe Lin Message-ID: Date: Tue, 30 Mar 2021 10:10:02 +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: <20210329232402.575396-6-mike.kravetz@oracle.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.179.86] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/3/30 7:23, Mike Kravetz wrote: > With the introduction of remove_hugetlb_page(), there is no need for > update_and_free_page to hold the hugetlb lock. Change all callers to > drop the lock before calling. > > With additional code modifications, this will allow loops which decrease > the huge page pool to drop the hugetlb_lock with each page to reduce > long hold times. > > The ugly unlock/lock cycle in free_pool_huge_page will be removed in > a subsequent patch which restructures free_pool_huge_page. > > Signed-off-by: Mike Kravetz > Acked-by: Michal Hocko > Reviewed-by: Muchun Song Looks good to me. Thanks! Reviewed-by: Miaohe Lin > --- > mm/hugetlb.c | 32 +++++++++++++++++++++++++++----- > 1 file changed, 27 insertions(+), 5 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 16beabbbbe49..dec7bd0dc63d 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1451,16 +1451,18 @@ static void __free_huge_page(struct page *page) > > if (HPageTemporary(page)) { > remove_hugetlb_page(h, page, false); > + spin_unlock(&hugetlb_lock); > update_and_free_page(h, page); > } else if (h->surplus_huge_pages_node[nid]) { > /* remove the page from active list */ > remove_hugetlb_page(h, page, true); > + spin_unlock(&hugetlb_lock); > update_and_free_page(h, page); > } else { > arch_clear_hugepage_flags(page); > enqueue_huge_page(h, page); > + spin_unlock(&hugetlb_lock); > } > - spin_unlock(&hugetlb_lock); > } > > /* > @@ -1741,7 +1743,13 @@ static int free_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed, > list_entry(h->hugepage_freelists[node].next, > struct page, lru); > remove_hugetlb_page(h, page, acct_surplus); > + /* > + * unlock/lock around update_and_free_page is temporary > + * and will be removed with subsequent patch. > + */ > + spin_unlock(&hugetlb_lock); > update_and_free_page(h, page); > + spin_lock(&hugetlb_lock); > ret = 1; > break; > } > @@ -1810,8 +1818,9 @@ int dissolve_free_huge_page(struct page *page) > } > remove_hugetlb_page(h, page, false); > h->max_huge_pages--; > + spin_unlock(&hugetlb_lock); > update_and_free_page(h, head); > - rc = 0; > + return 0; > } > out: > spin_unlock(&hugetlb_lock); > @@ -2674,22 +2683,35 @@ static void try_to_free_low(struct hstate *h, unsigned long count, > nodemask_t *nodes_allowed) > { > int i; > + struct page *page, *next; > + LIST_HEAD(page_list); > > if (hstate_is_gigantic(h)) > return; > > + /* > + * Collect pages to be freed on a list, and free after dropping lock > + */ > + INIT_LIST_HEAD(&page_list); > for_each_node_mask(i, *nodes_allowed) { > - struct page *page, *next; > struct list_head *freel = &h->hugepage_freelists[i]; > list_for_each_entry_safe(page, next, freel, lru) { > if (count >= h->nr_huge_pages) > - return; > + goto out; > if (PageHighMem(page)) > continue; > remove_hugetlb_page(h, page, false); > - update_and_free_page(h, page); > + list_add(&page->lru, &page_list); > } > } > + > +out: > + spin_unlock(&hugetlb_lock); > + list_for_each_entry_safe(page, next, &page_list, lru) { > + update_and_free_page(h, page); > + cond_resched(); > + } > + spin_lock(&hugetlb_lock); > } > #else > static inline void try_to_free_low(struct hstate *h, unsigned long count, >