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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 55590C433B4 for ; Tue, 6 Apr 2021 09:57:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 29EF1613C8 for ; Tue, 6 Apr 2021 09:57:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241051AbhDFJ57 (ORCPT ); Tue, 6 Apr 2021 05:57:59 -0400 Received: from mx2.suse.de ([195.135.220.15]:57782 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233842AbhDFJ55 (ORCPT ); Tue, 6 Apr 2021 05:57:57 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1617703068; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=PrzMnQvTadcMOrBNWUDd7HakkDHKU9nVmDx9/Wi5Qk0=; b=W5G/DuRyRImzG7aKBi4/jd627pDCv4Q/QbHMycXee+ZsQhYVJNowiy7SwsMGNQpOnyDzNI et8tKP+8IGLr2itDXAUOHSmOsBx6+yqeY9woEhZY9jM6l7gOw1F00aK5nU0ZUdqX4SNGOX iFpMnauW6O6Ef9rzzJbsQiWm9pipbLM= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id A1A23B12E; Tue, 6 Apr 2021 09:57:48 +0000 (UTC) Date: Tue, 6 Apr 2021 11:57:47 +0200 From: Michal Hocko To: Mike Kravetz Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Roman Gushchin , Shakeel Butt , Oscar Salvador , David Hildenbrand , Muchun Song , David Rientjes , Miaohe Lin , 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 Subject: Re: [PATCH v4 5/8] hugetlb: call update_and_free_page without hugetlb_lock Message-ID: References: <20210405230043.182734-1-mike.kravetz@oracle.com> <20210405230043.182734-6-mike.kravetz@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210405230043.182734-6-mike.kravetz@oracle.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 05-04-21 16:00:40, 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 Still looks good. Acked-by: Michal Hocko > --- > mm/hugetlb.c | 43 +++++++++++++++++++++++++++++++++---------- > 1 file changed, 33 insertions(+), 10 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index df2a3d1f632b..be6031a8e2a9 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1446,16 +1446,18 @@ 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); > } > > /* > @@ -1736,7 +1738,13 @@ 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; > } > @@ -1805,8 +1813,9 @@ 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); > @@ -2291,6 +2300,7 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page, > gfp_t gfp_mask = htlb_alloc_mask(h) | __GFP_THISNODE; > int nid = page_to_nid(old_page); > struct page *new_page; > + struct page *page_to_free; > int ret = 0; > > /* > @@ -2313,16 +2323,16 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page, > * Freed from under us. Drop new_page too. > */ > remove_hugetlb_page(h, new_page, false); > - update_and_free_page(h, new_page); > - goto unlock; > + page_to_free = new_page; > + goto unlock_free; > } else if (page_count(old_page)) { > /* > * Someone has grabbed the page, try to isolate it here. > * Fail with -EBUSY if not possible. > */ > remove_hugetlb_page(h, new_page, false); > - update_and_free_page(h, new_page); > spin_unlock(&hugetlb_lock); > + update_and_free_page(h, new_page); > if (!isolate_huge_page(old_page, list)) > ret = -EBUSY; > return ret; > @@ -2344,11 +2354,12 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page, > * enqueue_huge_page for new page. Net result is no change. > */ > remove_hugetlb_page(h, old_page, false); > - update_and_free_page(h, old_page); > enqueue_huge_page(h, new_page); > + page_to_free = old_page; > } > -unlock: > +unlock_free: > spin_unlock(&hugetlb_lock); > + update_and_free_page(h, page_to_free); > > return ret; > } > @@ -2671,22 +2682,34 @@ 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 > + */ > 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, > -- > 2.30.2 > -- Michal Hocko SUSE Labs