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=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 035EDC4338F for ; Tue, 3 Aug 2021 11:26:05 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7FF1E60EBC for ; Tue, 3 Aug 2021 11:26:04 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 7FF1E60EBC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id E576B6B0033; Tue, 3 Aug 2021 07:26:03 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DDF5E6B0036; Tue, 3 Aug 2021 07:26:03 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CA7136B005D; Tue, 3 Aug 2021 07:26:03 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0059.hostedemail.com [216.40.44.59]) by kanga.kvack.org (Postfix) with ESMTP id AD95A6B0033 for ; Tue, 3 Aug 2021 07:26:03 -0400 (EDT) Received: from smtpin37.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 5AA5F181AEF1E for ; Tue, 3 Aug 2021 11:26:03 +0000 (UTC) X-FDA: 78433540206.37.F440118 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf07.hostedemail.com (Postfix) with ESMTP id 6A6E21008A86 for ; Tue, 3 Aug 2021 11:26:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=BuLiq12RG7B36khxihK0IUw3DFZDJm8AYh2kdikH7as=; b=DU79JUdwPuDo5xJJBlBqhuRymq XSd0/JsKh9QWGkXc1vaPCOSm46mlm3MD1Wt+9J6UY/zxsY9Ys73QosNfI4V3UQVhFBrKCAPPSW7hh ouStu9WkOMaYpoGz+Wwcv4MPY+9nzZsKk+UUsw7zJPpyXjpxiPdwxtIatl5P0V7xIKpXEoAgG+w8o fAEUhurdlgp29ocMYODX8vhV4kuKYqHYhBCz1aIr0WEak5/g/l/SnrZBoIdOsh7xzodsuIt5G6lAV nL7yPtI8QRZyNhBDCLl+5ELB1WsBYiwhS6+fVSNLKPghvRqcBr4MI+zmJ4HBYIdRAbkOk9hgQOMwM PA5oHOsQ==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mAsYB-004ZRc-AN; Tue, 03 Aug 2021 11:25:40 +0000 Date: Tue, 3 Aug 2021 12:25:35 +0100 From: Matthew Wilcox To: Yu Zhao Cc: linux-mm@kvack.org, Andrew Morton , Hugh Dickins , "Kirill A . Shutemov" , Vlastimil Babka , Yang Shi , Zi Yan , linux-kernel@vger.kernel.org, Shuang Zhai Subject: Re: [PATCH 3/3] mm: don't remap clean subpages when splitting isolated thp Message-ID: References: <20210731063938.1391602-1-yuzhao@google.com> <20210731063938.1391602-4-yuzhao@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210731063938.1391602-4-yuzhao@google.com> Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=DU79JUdw; dmarc=none; spf=none (imf07.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-Stat-Signature: m76q56kbiia3ba9xenakfbwtzpemn4kq X-Rspamd-Queue-Id: 6A6E21008A86 X-Rspamd-Server: rspam01 X-HE-Tag: 1627989961-275461 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 Sat, Jul 31, 2021 at 12:39:38AM -0600, Yu Zhao wrote: > +++ b/mm/migrate.c > @@ -168,14 +168,53 @@ void putback_movable_pages(struct list_head *l) > } > } > > +static bool try_to_unmap_clean(struct page_vma_mapped_walk *pvmw, struct page *page) > +{ > + void *addr; > + bool dirty; > + > + VM_BUG_ON_PAGE(PageLRU(page), page); > + VM_BUG_ON_PAGE(PageCompound(page), page); > + VM_BUG_ON_PAGE(!PageAnon(page), page); > + VM_BUG_ON_PAGE(!PageLocked(page), page); > + VM_BUG_ON_PAGE(pte_present(*pvmw->pte), page); > + > + if (PageMlocked(page) || (pvmw->vma->vm_flags & VM_LOCKED)) > + return false; > + > + /* > + * The pmd entry mapping the old thp was flushed and the pte mapping > + * this subpage has been non present. Therefore, this subpage is > + * inaccessible. We don't need to remap it if it contains only zeros. > + */ > + addr = kmap_atomic(page); > + dirty = !!memchr_inv(addr, 0, PAGE_SIZE); > + kunmap_atomic(addr); kmap_local() is preferred now. Also, Linus has a particular hatred for the !! idiom; just compare against NULL.