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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 824CAC433F5 for ; Mon, 13 Sep 2021 12:13:03 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2E89E60F4C for ; Mon, 13 Sep 2021 12:13:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 2E89E60F4C Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id AB6D8900002; Mon, 13 Sep 2021 08:13:02 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A66486B0073; Mon, 13 Sep 2021 08:13:02 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 9557F900002; Mon, 13 Sep 2021 08:13:02 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0081.hostedemail.com [216.40.44.81]) by kanga.kvack.org (Postfix) with ESMTP id 871C16B0072 for ; Mon, 13 Sep 2021 08:13:02 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 458BC82499B9 for ; Mon, 13 Sep 2021 12:13:02 +0000 (UTC) X-FDA: 78582439404.29.12FDFAF Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by imf13.hostedemail.com (Postfix) with ESMTP id C9DEA102CBE1 for ; Mon, 13 Sep 2021 12:13:01 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 7E34321F92; Mon, 13 Sep 2021 12:13:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1631535180; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=zzVUxmb5DpJSe2zaB7Ppa7a2SNgZQz8/SnCpXyr+Mx0=; b=QtDHPwuc2qRw9wHW5wjLVix9W0ABTmUWUVAH8lsvMWuoFPPWqEKW7LPOtIur2IouXcwRm/ aPBxBO/jLfvTFg6LBiZ7wvCrsiJacP3ndM7SvXWxWUu4Wwbm3GXwW2ZMbauzWRClW5wjYl +F96piuQ5EdDMZ1c/QT+aJXpmXd7UBY= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 5095AA3B93; Mon, 13 Sep 2021 12:13:00 +0000 (UTC) Date: Mon, 13 Sep 2021 14:12:59 +0200 From: Michal Hocko To: Miaohe Lin Cc: akpm@linux-foundation.org, david@redhat.com, vbabka@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm/page_isolation: fix potential missing call to unset_migratetype_isolate() Message-ID: References: <20210913115125.33617-1-linmiaohe@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210913115125.33617-1-linmiaohe@huawei.com> Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=QtDHPwuc; spf=pass (imf13.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.28 as permitted sender) smtp.mailfrom=mhocko@suse.com; dmarc=pass (policy=quarantine) header.from=suse.com X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: C9DEA102CBE1 X-Stat-Signature: o9ytqrq1in84b1f9cenkkfa3nwcpnfj3 X-HE-Tag: 1631535181-951032 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 Mon 13-09-21 19:51:25, Miaohe Lin wrote: > In start_isolate_page_range() undo path, pfn_to_online_page() just checks > the first pfn in a pageblock while __first_valid_page() will traverse the > pageblock until the first online pfn is found. So we may miss the call to > unset_migratetype_isolate() in undo path and pages will remain isolated > unexpectedly. Fix this by calling undo_isolate_page_range() and this will > also help to simplify the code further. I like the clean up part but is this a real problem that requires CC stable? Have you ever seen this to be a real problem? It looks like something based on reading the code. > Fixes: 2ce13640b3f4 ("mm: __first_valid_page skip over offline pages") > Signed-off-by: Miaohe Lin > Cc: > --- > v1->v2: > Simplify the code further per David Hildenbrand. > --- > mm/page_isolation.c | 20 +++----------------- > 1 file changed, 3 insertions(+), 17 deletions(-) > > diff --git a/mm/page_isolation.c b/mm/page_isolation.c > index a95c2c6562d0..f93cc63d8fa1 100644 > --- a/mm/page_isolation.c > +++ b/mm/page_isolation.c > @@ -183,7 +183,6 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, > unsigned migratetype, int flags) > { > unsigned long pfn; > - unsigned long undo_pfn; > struct page *page; > > BUG_ON(!IS_ALIGNED(start_pfn, pageblock_nr_pages)); > @@ -193,25 +192,12 @@ int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn, > pfn < end_pfn; > pfn += pageblock_nr_pages) { > page = __first_valid_page(pfn, pageblock_nr_pages); > - if (page) { > - if (set_migratetype_isolate(page, migratetype, flags)) { > - undo_pfn = pfn; > - goto undo; > - } > + if (page && set_migratetype_isolate(page, migratetype, flags)) { > + undo_isolate_page_range(start_pfn, pfn, migratetype); > + return -EBUSY; > } > } > return 0; > -undo: > - for (pfn = start_pfn; > - pfn < undo_pfn; > - pfn += pageblock_nr_pages) { > - struct page *page = pfn_to_online_page(pfn); > - if (!page) > - continue; > - unset_migratetype_isolate(page, migratetype); > - } > - > - return -EBUSY; > } > > /* > -- > 2.23.0 -- Michal Hocko SUSE Labs