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=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 14EB1C2BD0C for ; Tue, 13 Oct 2020 23:52:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CFE3B22201 for ; Tue, 13 Oct 2020 23:52:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602633142; bh=vNMA6MVhwcudTM+q+Y6GKJx0Ymx8ggL+IeNOm1GF1yo=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=1F2g23T9j4c1phDnl5a42pvdZqQb9hXJRRjW8BDuCV3WgkFM2CIpJVMW4dXDhYTMR 3ZM5cmSyzsfF5xChdweHGuDedCq7ocJqWaK4NB60hXsYMwl+gS9TRVuJPstSMuWnjn SlX3ZX6nUdOotXU6hILOOvKhG1OwMxZWXUqL/baE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728809AbgJMXwV (ORCPT ); Tue, 13 Oct 2020 19:52:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:37086 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728770AbgJMXwN (ORCPT ); Tue, 13 Oct 2020 19:52:13 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EEED122200; Tue, 13 Oct 2020 23:52:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602633132; bh=vNMA6MVhwcudTM+q+Y6GKJx0Ymx8ggL+IeNOm1GF1yo=; h=Date:From:To:Subject:In-Reply-To:From; b=sCxSL+I9/RNAS1iL+7APXDWEKMVbnpvXptaKKVjPn99Hwds5bDJs4EbHkIadk83lc 9yJIprNBJNfl/bhXNN7lRXWszWScpfSNaRMG2ZlyKGGLHmF4LVLSg63zOxs+ZsPpWx 97+hkha0jeJzKYYtLDf1KxhelP7z7TEr/CRlf1yI= Date: Tue, 13 Oct 2020 16:52:11 -0700 From: Andrew Morton To: akpm@linux-foundation.org, alexander.h.duyck@linux.intel.com, cai@lca.pw, david@redhat.com, hughd@google.com, iamjoonsoo.kim@lge.com, linux-mm@kvack.org, mgorman@techsingularity.net, mhocko@suse.com, mm-commits@vger.kernel.org, npiggin@gmail.com, shy828301@gmail.com, torvalds@linux-foundation.org, ying.huang@intel.com, yuzhao@google.com Subject: [patch 070/181] mm: remove superfluous __ClearPageActive() Message-ID: <20201013235211.c2AQxgjbm%akpm@linux-foundation.org> In-Reply-To: <20201013164658.3bfd96cc224d8923e66a9f4e@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Yu Zhao Subject: mm: remove superfluous __ClearPageActive() To activate a page, mark_page_accessed() always holds a reference on it. It either gets a new reference when adding a page to lru_pvecs.activate_page or reuses an existing one it previously got when it added a page to lru_pvecs.lru_add. So it doesn't call SetPageActive() on a page that doesn't have any reference left. Therefore, the race is impossible these days (I didn't brother to dig into its history). For other paths, namely reclaim and migration, a reference count is always held while calling SetPageActive() on a page. SetPageSlabPfmemalloc() also uses SetPageActive(), but it's irrelevant to LRU pages. Link: http://lkml.kernel.org/r/20200818184704.3625199-2-yuzhao@google.com Signed-off-by: Yu Zhao Reviewed-by: Yang Shi Cc: Alexander Duyck Cc: David Hildenbrand Cc: Huang Ying Cc: Hugh Dickins Cc: Joonsoo Kim Cc: Mel Gorman Cc: Michal Hocko Cc: Nicholas Piggin Cc: Qian Cai Signed-off-by: Andrew Morton --- mm/memremap.c | 2 -- mm/swap.c | 2 -- 2 files changed, 4 deletions(-) --- a/mm/memremap.c~mm-remove-superfluous-__clearpageactive +++ a/mm/memremap.c @@ -494,8 +494,6 @@ void free_devmap_managed_page(struct pag return; } - /* Clear Active bit in case of parallel mark_page_accessed */ - __ClearPageActive(page); __ClearPageWaiters(page); mem_cgroup_uncharge(page); --- a/mm/swap.c~mm-remove-superfluous-__clearpageactive +++ a/mm/swap.c @@ -943,8 +943,6 @@ void release_pages(struct page **pages, del_page_from_lru_list(page, lruvec, page_off_lru(page)); } - /* Clear Active bit in case of parallel mark_page_accessed */ - __ClearPageActive(page); __ClearPageWaiters(page); list_add(&page->lru, &pages_to_free); _