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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB7CDC0015E for ; Mon, 17 Jul 2023 15:51:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 24D486B0072; Mon, 17 Jul 2023 11:51:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1FD698D0002; Mon, 17 Jul 2023 11:51:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0EDD48D0001; Mon, 17 Jul 2023 11:51:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id EF8C26B0072 for ; Mon, 17 Jul 2023 11:51:07 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id AD8CF4042A for ; Mon, 17 Jul 2023 15:51:07 +0000 (UTC) X-FDA: 81021542574.30.85B30BA Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf03.hostedemail.com (Postfix) with ESMTP id B7AE02000F for ; Mon, 17 Jul 2023 15:51:05 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=none; spf=pass (imf03.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1689609065; a=rsa-sha256; cv=none; b=WfVCZCTiIIUar5wIxxLgTJRTGb5p7Lpl/AHKtHL9TlxyeWE2iajVCc1pVitglSEe01Co/G EloQA6vouz5N0A2UfVqD0FrScrzA+bROiBoXU1qjOBW274X4Lw7HxPNC8CP9XM7oBI0u7e 0dR+0UwyeQUva3isUikLeqvBj35/KWI= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=none; spf=pass (imf03.hostedemail.com: domain of ryan.roberts@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=ryan.roberts@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1689609065; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=BGYwyxjaWxOpgpM0wd9OJUNYEnQ8HUvlkegQEbmeknc=; b=SDDzJQiEVzVN0tx5UlKGOPSLX98eBQ/ebfULq0I+1WfqfQDaMeOBgtrA701zCX14mKn+B5 Yi6gjxiKd6dPsOFyflQF0fy7tpit8OGTXdMHUHS7GSpOlxChpR3bRasIyUyNSy2sE1xSsm f8fVZ/VT2u6d+kUDwR6RK5utWtSa9Mo= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3445AC15; Mon, 17 Jul 2023 08:51:48 -0700 (PDT) Received: from [10.57.76.30] (unknown [10.57.76.30]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 543FB3F738; Mon, 17 Jul 2023 08:51:03 -0700 (PDT) Message-ID: Date: Mon, 17 Jul 2023 16:51:01 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v1 2/3] mm: Implement folio_remove_rmap_range() To: Zi Yan Cc: Andrew Morton , Matthew Wilcox , Yin Fengwei , David Hildenbrand , Yu Zhao , Yang Shi , "Huang, Ying" , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20230717143110.260162-1-ryan.roberts@arm.com> <20230717143110.260162-3-ryan.roberts@arm.com> From: Ryan Roberts In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: B7AE02000F X-Stat-Signature: i4eejjmqr8r8o1ptpdo8eohzfw4oyeka X-HE-Tag: 1689609065-182026 X-HE-Meta: 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 DSmBwLp0 Y6M+a2k7pe/KdtisDzsHe2nYyHmr0lJSYdLbrhyOXvA9lcNCcVCrpKXIqdIGJwgtxBG5PAgh+AHZtjGM/bwxU9821a9ClJKifyZJo88GDaYy7JqgQD16SmoODZEUURQtIq2680p026tdqKWEgtHZ8zd9Lc9RNTRx0pnyQmE/OjWsQQHCZOCvMsU1uQoz5ULgnL6onXn8ZkCrYIuIFDDVHdci1TmtUfOvJh+K5QdkdGZ3y4Zk= 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 17/07/2023 16:09, Zi Yan wrote: > On 17 Jul 2023, at 10:31, Ryan Roberts wrote: > >> Like page_remove_rmap() but batch-removes the rmap for a range of pages >> belonging to a folio. This can provide a small speedup due to less >> manipuation of the various counters. But more crucially, if removing the >> rmap for all pages of a folio in a batch, there is no need to >> (spuriously) add it to the deferred split list, which saves significant >> cost when there is contention for the split queue lock. >> >> All contained pages are accounted using the order-0 folio (or base page) >> scheme. >> >> Signed-off-by: Ryan Roberts >> --- >> include/linux/rmap.h | 2 ++ >> mm/rmap.c | 65 ++++++++++++++++++++++++++++++++++++++++++++ >> 2 files changed, 67 insertions(+) >> >> diff --git a/include/linux/rmap.h b/include/linux/rmap.h >> index b87d01660412..f578975c12c0 100644 >> --- a/include/linux/rmap.h >> +++ b/include/linux/rmap.h >> @@ -200,6 +200,8 @@ void page_add_file_rmap(struct page *, struct vm_area_struct *, >> bool compound); >> void page_remove_rmap(struct page *, struct vm_area_struct *, >> bool compound); >> +void folio_remove_rmap_range(struct folio *folio, struct page *page, >> + int nr, struct vm_area_struct *vma); >> >> void hugepage_add_anon_rmap(struct page *, struct vm_area_struct *, >> unsigned long address, rmap_t flags); >> diff --git a/mm/rmap.c b/mm/rmap.c >> index 2baf57d65c23..1da05aca2bb1 100644 >> --- a/mm/rmap.c >> +++ b/mm/rmap.c >> @@ -1359,6 +1359,71 @@ void page_add_file_rmap(struct page *page, struct vm_area_struct *vma, >> mlock_vma_folio(folio, vma, compound); >> } >> >> +/* >> + * folio_remove_rmap_range - take down pte mappings from a range of pages >> + * belonging to a folio. All pages are accounted as small pages. >> + * @folio: folio that all pages belong to >> + * @page: first page in range to remove mapping from >> + * @nr: number of pages in range to remove mapping from > > We might need some checks to make sure [page, page+nr] is in the range of > the folio. Something like: > > page >= &folio->page && page + nr < (&folio->page + folio_nr_pages(folio)) No problem. Is a VM_WARN_ON() appropriate for something like this? > >> + * @vma: the vm area from which the mapping is removed >> + * >> + * The caller needs to hold the pte lock. >> + */ >> +void folio_remove_rmap_range(struct folio *folio, struct page *page, >> + int nr, struct vm_area_struct *vma) >> +{ >> + atomic_t *mapped = &folio->_nr_pages_mapped; >> + int nr_unmapped = 0; >> + int nr_mapped; >> + bool last; >> + enum node_stat_item idx; >> + >> + if (unlikely(folio_test_hugetlb(folio))) { >> + VM_WARN_ON_FOLIO(1, folio); >> + return; >> + } >> + >> + if (!folio_test_large(folio)) { >> + /* Is this the page's last map to be removed? */ >> + last = atomic_add_negative(-1, &page->_mapcount); >> + nr_unmapped = last; >> + } else { >> + for (; nr != 0; nr--, page++) { >> + /* Is this the page's last map to be removed? */ >> + last = atomic_add_negative(-1, &page->_mapcount); >> + if (last) { >> + /* Page still mapped if folio mapped entirely */ >> + nr_mapped = atomic_dec_return_relaxed(mapped); >> + if (nr_mapped < COMPOUND_MAPPED) >> + nr_unmapped++; >> + } >> + } >> + } >> + >> + if (nr_unmapped) { >> + idx = folio_test_anon(folio) ? NR_ANON_MAPPED : NR_FILE_MAPPED; >> + __lruvec_stat_mod_folio(folio, idx, -nr_unmapped); >> + >> + /* >> + * Queue anon THP for deferred split if we have just unmapped at >> + * least 1 page, while at least 1 page remains mapped. >> + */ >> + if (folio_test_large(folio) && folio_test_anon(folio)) >> + if (nr_mapped) >> + deferred_split_folio(folio); >> + } >> + >> + /* >> + * It would be tidy to reset folio_test_anon mapping when fully >> + * unmapped, but that might overwrite a racing page_add_anon_rmap >> + * which increments mapcount after us but sets mapping before us: >> + * so leave the reset to free_pages_prepare, and remember that >> + * it's only reliable while mapped. >> + */ >> + >> + munlock_vma_folio(folio, vma, false); >> +} >> + >> /** >> * page_remove_rmap - take down pte mapping from a page >> * @page: page to remove mapping from >> -- >> 2.25.1 > > Everything else looks good to me. Reviewed-by: Zi Yan > > -- > Best Regards, > Yan, Zi