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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 04F29C49ED7 for ; Mon, 16 Sep 2019 10:36:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BEB8E214AF for ; Mon, 16 Sep 2019 10:36:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1568630165; bh=pomYLwRYbCEbqyd6K6P8sKMkRv00Pd8/VCRXvD/0QKw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=HXoUSPgTSk7omhasEh4ZSIEtD6JQqxY9uggaFj6vZ0G11vH9HJk1/rE9FiPSa8tJw 7Ql8rG2jpfCE/xNoDPwYR6W5vk/ppp7WiZQbtoDkOFn5JAq6T/T8bEdESuLsBp9eik iwvmiZfaNCZAuaEScjCg18oWC4XiVEKx3txarfWs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731001AbfIPKgF (ORCPT ); Mon, 16 Sep 2019 06:36:05 -0400 Received: from mx2.suse.de ([195.135.220.15]:34700 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726604AbfIPKgE (ORCPT ); Mon, 16 Sep 2019 06:36:04 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 2BC22ABD0; Mon, 16 Sep 2019 10:36:03 +0000 (UTC) Date: Mon, 16 Sep 2019 12:36:02 +0200 From: Michal Hocko To: "Kirill A. Shutemov" Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: Re: [PATCH] mm, thp: Do not queue fully unmapped pages for deferred split Message-ID: <20190916103602.GD10231@dhcp22.suse.cz> References: <20190913091849.11151-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190913091849.11151-1-kirill.shutemov@linux.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 13-09-19 12:18:49, Kirill A. Shutemov wrote: > Adding fully unmapped pages into deferred split queue is not productive: > these pages are about to be freed or they are pinned and cannot be split > anyway. > > Signed-off-by: Kirill A. Shutemov > --- > mm/rmap.c | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) > > diff --git a/mm/rmap.c b/mm/rmap.c > index 003377e24232..45388f1bf317 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -1271,12 +1271,20 @@ static void page_remove_anon_compound_rmap(struct page *page) > if (TestClearPageDoubleMap(page)) { > /* > * Subpages can be mapped with PTEs too. Check how many of > - * themi are still mapped. > + * them are still mapped. > */ > for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) { > if (atomic_add_negative(-1, &page[i]._mapcount)) > nr++; > } > + > + /* > + * Queue the page for deferred split if at least one small > + * page of the compound page is unmapped, but at least one > + * small page is still mapped. > + */ > + if (nr && nr < HPAGE_PMD_NR) > + deferred_split_huge_page(page); You've set nr to zero in the for loop so this cannot work AFAICS. > } else { > nr = HPAGE_PMD_NR; > } > @@ -1284,10 +1292,8 @@ static void page_remove_anon_compound_rmap(struct page *page) > if (unlikely(PageMlocked(page))) > clear_page_mlock(page); > > - if (nr) { > + if (nr) > __mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, -nr); > - deferred_split_huge_page(page); > - } > } > > /** > -- > 2.21.0 -- Michal Hocko SUSE Labs