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 DACF7C433F5 for ; Fri, 17 Dec 2021 19:07:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 56ACD6B0075; Fri, 17 Dec 2021 14:06:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 51A486B0078; Fri, 17 Dec 2021 14:06:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3E1FA6B007B; Fri, 17 Dec 2021 14:06:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0168.hostedemail.com [216.40.44.168]) by kanga.kvack.org (Postfix) with ESMTP id 30CCF6B0075 for ; Fri, 17 Dec 2021 14:06:56 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id EA3938249980 for ; Fri, 17 Dec 2021 19:06:45 +0000 (UTC) X-FDA: 78928217970.27.C69EE0A Received: from mail-ed1-f52.google.com (mail-ed1-f52.google.com [209.85.208.52]) by imf13.hostedemail.com (Postfix) with ESMTP id C262620015 for ; Fri, 17 Dec 2021 19:06:39 +0000 (UTC) Received: by mail-ed1-f52.google.com with SMTP id z9so11615348edb.5 for ; Fri, 17 Dec 2021 11:06:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=CdWa3VZPKatai3gF8Z+Urkz4ghMCS8ZDk6ZieZNqaIs=; b=ZIJEwmc3dUjMQ8EZETYRFKYSgxnB7pGz8xLptALl9BU9T00ihDHDK5FDNa1lYMJvjN MezA8fFtv3wu7YNOlCqI1D6Xa330lfBp1fRlHGc32VBxQcXb7/QN1MngCijkXmAK9K4f IowAITb4zD445Ivb0clvo+Fdia78+IZV9ZhBAIm9gxxL/jJAjzAtK4xRBVu0xKjGg9mN vNwY41BUKpZBiaGNxBoTXyWQIHN8xWofKrbQGG+dSAcD/S4srVPrX+fFafoa3Y7Z8qo7 o3HJSdrU23xhXC0txymOh02wxJhmZEgWKAdYqxmnvXwBqAYOmDBa1Fd0cRhL+OEHOtU2 EQvQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=CdWa3VZPKatai3gF8Z+Urkz4ghMCS8ZDk6ZieZNqaIs=; b=lkmgg5gQNumO8f8p6NrS77oIukUW3IZ1IkGGOevLAd6ZgefwJw7SnktQMxN/ap4jmV 10PxhQnkLGHe8S70GpQjAbvoY2TzlLALmw3tADsjl0nIeOnr9BLmqfcg+RGOCUyLXuJc 8Wr/ge6wuZfdPFmSG32U9Y4TSz97z0gJ0uATHdFfqZCoJGoPEtkABN/vVPjTQS61L+lP sCGfDr+QkIzeKHVsfwyDlNQJX3uttY9gn7NVvWZj+35yF1jxfZ2FGkHgQwhV6BalUP6m QNJNgYGezRhFX39VAUMSaNjagSjhjWlFRwBMmRbN64DW/B6L3OVyUrIIIyRegDru7IFP 0Rng== X-Gm-Message-State: AOAM530Guyi354FPiz5aq4j7IT9lKoEiP2aRFlJczqVakDxpp6j09v0h Chmgem7Z7lsBz5lCPIsltbwctvHmU6wpBUojux+lJOKQ X-Google-Smtp-Source: ABdhPJwxDib3+r9/gWzmhjMAr3HWYlGtU2PoZVL15X+h8JOVYHxqutwxRbVQVuEYBvrj86uySi9x5gAUnGZyFvklEQY= X-Received: by 2002:a50:c38c:: with SMTP id h12mr4189423edf.72.1639768004419; Fri, 17 Dec 2021 11:06:44 -0800 (PST) MIME-Version: 1.0 References: <20211217113049.23850-1-david@redhat.com> <20211217113049.23850-3-david@redhat.com> In-Reply-To: <20211217113049.23850-3-david@redhat.com> From: Yang Shi Date: Fri, 17 Dec 2021 11:06:31 -0800 Message-ID: Subject: Re: [PATCH v1 02/11] mm: thp: consolidate mapcount logic on THP split To: David Hildenbrand Cc: Linux Kernel Mailing List , Andrew Morton , Hugh Dickins , Linus Torvalds , David Rientjes , Shakeel Butt , John Hubbard , Jason Gunthorpe , Mike Kravetz , Mike Rapoport , "Kirill A . Shutemov" , Matthew Wilcox , Vlastimil Babka , Jann Horn , Michal Hocko , Nadav Amit , Rik van Riel , Roman Gushchin , Andrea Arcangeli , Peter Xu , Donald Dutile , Christoph Hellwig , Oleg Nesterov , Jan Kara , Linux MM , linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=ZIJEwmc3; spf=pass (imf13.hostedemail.com: domain of shy828301@gmail.com designates 209.85.208.52 as permitted sender) smtp.mailfrom=shy828301@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: C262620015 X-Stat-Signature: 19t4b77zeum8gbgkqxmt51yeu5f46ffz X-HE-Tag: 1639767999-169604 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 Fri, Dec 17, 2021 at 3:33 AM David Hildenbrand wrote: > > Let's consolidate the mapcount logic to make it easier to understand and > to prepare for further changes. > > Reviewed-by: Peter Xu > Signed-off-by: David Hildenbrand Reviewed-by: Yang Shi > --- > mm/huge_memory.c | 18 +++++++++++------- > 1 file changed, 11 insertions(+), 7 deletions(-) > > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index e5483347291c..4751d03947da 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2101,21 +2101,25 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd, > pte = pte_offset_map(&_pmd, addr); > BUG_ON(!pte_none(*pte)); > set_pte_at(mm, addr, pte, entry); > - if (!pmd_migration) > - atomic_inc(&page[i]._mapcount); > pte_unmap(pte); > } > > if (!pmd_migration) { > + /* Sub-page mapcount accounting for above small mappings. */ > + int val = 1; > + > /* > * Set PG_double_map before dropping compound_mapcount to avoid > * false-negative page_mapped(). > + * > + * The first to set PageDoubleMap() has to increment all > + * sub-page mapcounts by one. > */ > - if (compound_mapcount(page) > 1 && > - !TestSetPageDoubleMap(page)) { > - for (i = 0; i < HPAGE_PMD_NR; i++) > - atomic_inc(&page[i]._mapcount); > - } > + if (compound_mapcount(page) > 1 && !TestSetPageDoubleMap(page)) > + val++; > + > + for (i = 0; i < HPAGE_PMD_NR; i++) > + atomic_add(val, &page[i]._mapcount); > > lock_page_memcg(page); > if (atomic_add_negative(-1, compound_mapcount_ptr(page))) { > -- > 2.31.1 >