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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 CF5DEC433E4 for ; Tue, 14 Jul 2020 11:06:23 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 67C92221FC for ; Tue, 14 Jul 2020 11:06:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 67C92221FC Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A62EF6B0002; Tue, 14 Jul 2020 07:06:22 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A12FE6B0003; Tue, 14 Jul 2020 07:06:22 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 900C46B0005; Tue, 14 Jul 2020 07:06:22 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0077.hostedemail.com [216.40.44.77]) by kanga.kvack.org (Postfix) with ESMTP id 7BE606B0002 for ; Tue, 14 Jul 2020 07:06:22 -0400 (EDT) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 1AABF181AC9CC for ; Tue, 14 Jul 2020 11:06:22 +0000 (UTC) X-FDA: 77036402604.07.low25_310ddbd26ef0 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin07.hostedemail.com (Postfix) with ESMTP id E05D51803F9A3 for ; Tue, 14 Jul 2020 11:06:21 +0000 (UTC) X-HE-Tag: low25_310ddbd26ef0 X-Filterd-Recvd-Size: 2257 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf19.hostedemail.com (Postfix) with ESMTP for ; Tue, 14 Jul 2020 11:06:21 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 8D897ACDB; Tue, 14 Jul 2020 11:06:22 +0000 (UTC) Subject: Re: [PATCH v2 1/6] mm: Handle page->mapping better in dump_page To: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org Cc: Andrew Morton , John Hubbard , "Kirill A. Shutemov" , William Kucharski , Mike Rapoport References: <20200709202117.7216-1-willy@infradead.org> <20200709202117.7216-2-willy@infradead.org> From: Vlastimil Babka Message-ID: Date: Tue, 14 Jul 2020 13:06:20 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200709202117.7216-2-willy@infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: E05D51803F9A3 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 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 7/9/20 10:21 PM, Matthew Wilcox (Oracle) wrote: > If we can't call page_mapping() to get the page mapping, handle the > anon/ksm/movable bits correctly. > > Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Vlastimil Babka John's updated comment looks fine too. > --- > mm/debug.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/mm/debug.c b/mm/debug.c > index 4f376514744d..e5de63406b59 100644 > --- a/mm/debug.c > +++ b/mm/debug.c > @@ -70,7 +70,12 @@ void __dump_page(struct page *page, const char *reason) > > if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) { > /* Corrupt page, cannot call page_mapping */ > - mapping = page->mapping; > + unsigned long tmp = (unsigned long)page->mapping; > + > + if (tmp & PAGE_MAPPING_ANON) > + mapping = NULL; > + else > + mapping = (void *)(tmp & ~PAGE_MAPPING_FLAGS); > head = page; > compound = false; > } else { >