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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E2E3C433FE for ; Tue, 22 Nov 2022 09:13:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233221AbiKVJNw (ORCPT ); Tue, 22 Nov 2022 04:13:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47958 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232654AbiKVJNp (ORCPT ); Tue, 22 Nov 2022 04:13:45 -0500 Received: from mail-qk1-x72f.google.com (mail-qk1-x72f.google.com [IPv6:2607:f8b0:4864:20::72f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5FBFA63A5 for ; Tue, 22 Nov 2022 01:13:44 -0800 (PST) Received: by mail-qk1-x72f.google.com with SMTP id j26so2664130qki.10 for ; Tue, 22 Nov 2022 01:13:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to; bh=7xqdWpmMgK4TlDGSJjLz9IABXgjJRE62xPUxcQSf0wk=; b=O+mOhBKwBvKXkrpaR3qctTFgHdCTbmxJx9hfOl5YVIJFKz5hMMUW9G25INF+60AZ7H F0HQ5g+r6nJc6Gci2GztjHTAdqYVta6oPs3isV4NoKvbEBa5xKmRZJSmQ+5x8Zz0DXrJ vb4OPfS1R3AevGCJOAEn9TfIPY3EEpBhE3qScjWTtIe45TDD40nd2dWSml/W2hOHgikN 6Jny/WbU89Tyc2bIii7PVjlWQ2UUv0l8DxWA7AoWzSY7UeEwq/q0iMbyoDa1HsNXOsx/ Qzg0Vt5MqLZ/IP9nE8zye1ggzp3kWRVJJrB/k5cYuJaXIZxNdiMfOJvwjAslqUtLZ3c3 edig== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=7xqdWpmMgK4TlDGSJjLz9IABXgjJRE62xPUxcQSf0wk=; b=6cTyu7fMt9UEVaW/Spo24LfzOiAozqusQWx3eS/7IOQ6crhwuNnMipVXsF5VzucRzb fE3NX7z/YgzHIhUE/m3iARohsVmeMmbzXPGfawiKR5utdGnESAb6DHqUhcgFqBKxuJKg uHk2tZY/PGGL2+ZqpiraUUZ5TWqBL/1vLPitRKLcUufE7+0H/3L3S+Oor3KCTVwrYDkZ KR2ObGX6N2+k3w+9tFrWl8xiksfwdnWMsLnSHyatTIyJh7CtCRrDhCesTX1BJuUy9dkB 2afsX4iBynsD94pq5QFyzwz7loZiXcaHQMLuado5tyVlCdxnEQYdSML9opV1/ZiLmhf/ ZkSQ== X-Gm-Message-State: ANoB5pkW/LZjvd7OXrKTQS3rPdx3rBeaZccKJkukcfv0Cfv3Juq8l/+a 2HACr/GpHDP5A9H7LvpZNG7xWw== X-Google-Smtp-Source: AA0mqf4efPgyC6I9oPi8Nox4ddRnpIfoEy3+l57wAnRX7coydzZIpyvy5Dgy1rZtvpX/7WWu9lhQZg== X-Received: by 2002:a37:b03:0:b0:6fa:9d10:1784 with SMTP id 3-20020a370b03000000b006fa9d101784mr20331534qkl.627.1669108423412; Tue, 22 Nov 2022 01:13:43 -0800 (PST) Received: from ripple.attlocal.net (172-10-233-147.lightspeed.sntcca.sbcglobal.net. [172.10.233.147]) by smtp.gmail.com with ESMTPSA id bs42-20020a05620a472a00b006b61b2cb1d2sm9741158qkb.46.2022.11.22.01.13.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Nov 2022 01:13:42 -0800 (PST) Date: Tue, 22 Nov 2022 01:13:39 -0800 (PST) From: Hugh Dickins X-X-Sender: hugh@ripple.attlocal.net To: "Kirill A. Shutemov" cc: Hugh Dickins , Andrew Morton , Yu Zhao , Linus Torvalds , Johannes Weiner , Matthew Wilcox , David Hildenbrand , Vlastimil Babka , Peter Xu , Yang Shi , John Hubbard , Mike Kravetz , Sidhartha Kumar , Muchun Song , Miaohe Lin , Naoya Horiguchi , Mina Almasry , James Houghton , Zach O'Keefe , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/3 fix] mm,thp,rmap: subpages_mapcount of PTE-mapped subpages: fix In-Reply-To: <20221121123812.4sxk7ewzfhdqq6zs@box.shutemov.name> Message-ID: <536d9a99-1cbb-d05d-21bf-4cc8d032692@google.com> References: <5f52de70-975-e94f-f141-543765736181@google.com> <78fa518-85b5-32c0-ee92-537fa46131f6@google.com> <759077a6-a08-5bb0-a0b6-53be2fe8b56a@google.com> <7a4f5e5e-de33-dace-c526-4a3d3cf5f6e0@google.com> <20221121123812.4sxk7ewzfhdqq6zs@box.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 21 Nov 2022, Kirill A. Shutemov wrote: > On Fri, Nov 18, 2022 at 05:35:05PM -0800, Hugh Dickins wrote: ... > > --- a/mm/rmap.c > > +++ b/mm/rmap.c > > @@ -1281,7 +1281,7 @@ void page_add_anon_rmap(struct page *page, > > struct compound_mapcounts mapcounts; > > int nr = 0, nr_pmdmapped = 0; > > bool compound = flags & RMAP_COMPOUND; > > - bool first; > > + bool first = true; > > > > if (unlikely(PageKsm(page))) > > lock_page_memcg(page); > > Other option is to drop PageTransHuge() check that you already claim to be > redundant. > > Or have else BUG() to catch cases where the helper called with > compound=true on non-THP page. I'm sticking with the "first = true". I did receive a report of bloating some tiny config a little, on the very first series, so I've been on guard since then about adding THP code where the optimizer cannot see to remove it: so do want to keep the PageTransHuge check in there. Could be done in other ways, yes, but I'd ended up feeling this was the best compromise. Hugh