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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 11CFAC33CB3 for ; Tue, 14 Jan 2020 12:04:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E5AB724672 for ; Tue, 14 Jan 2020 12:04:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729678AbgANMEf (ORCPT ); Tue, 14 Jan 2020 07:04:35 -0500 Received: from mx2.suse.de ([195.135.220.15]:41866 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725956AbgANMEf (ORCPT ); Tue, 14 Jan 2020 07:04:35 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 9E1C9AE34; Tue, 14 Jan 2020 12:04:32 +0000 (UTC) Subject: [PATCH] mm, debug: always print flags in dump_page() To: Michal Hocko , linux-mm@kvack.org, Andrew Morton Cc: Anshuman Khandual , David Hildenbrand , Qian Cai , Oscar Salvador , Mel Gorman , Mike Rapoport , Dan Williams , Pavel Tatashin , linux-kernel@vger.kernel.org, Ralph Campbell References: <49fa7dea-00ac-155f-e7b7-eeca206556b5@arm.com> <6A58E80B-7A5F-4CAD-ACF1-89BCCBE4D3B1@lca.pw> <20200114091013.GD19428@dhcp22.suse.cz> <1f3ff7fc-2f6b-d8e5-85a5-078f0e1a0daf@suse.cz> <20200114113230.GM19428@dhcp22.suse.cz> From: Vlastimil Babka Message-ID: <9f884d5c-ca60-dc7b-219c-c081c755fab6@suse.cz> Date: Tue, 14 Jan 2020 13:04:31 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.1 MIME-Version: 1.0 In-Reply-To: <20200114113230.GM19428@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/14/20 12:32 PM, Michal Hocko wrote: > On Tue 14-01-20 11:23:52, Vlastimil Babka wrote: >> On 1/14/20 10:10 AM, Michal Hocko wrote: >> > [Cc Ralph] >> >> The reason is dump_page() does not print page->flags universally >> >> and only does so for KSM, Anon and File pages while excluding >> >> reserved pages at boot. Wondering should not we make printing >> >> page->flags universal ? >> > >> > We used to do that and this caught me as a surprise when looking again. >> > This is a result of 76a1850e4572 ("mm/debug.c: __dump_page() prints an >> > extra line") which is a cleanup patch and I suspect this result was not >> > anticipated. >> > >> > The following will do the trick but I cannot really say I like the code >> > duplication. pr_cont in this case sounds like a much cleaner solution to >> > me. >> >> How about this then? > > Yes makes sense as well. Ok here's a proper formatted patch ----8<---- >From 7b673c45bc16526586ae8ea6fba416a547baa04e Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Tue, 14 Jan 2020 12:52:48 +0100 Subject: [PATCH] mm, debug: always print flags in dump_page() Commit 76a1850e4572 ("mm/debug.c: __dump_page() prints an extra line") inadvertently removed printing of page flags for pages that are neither anon nor ksm nor have a mapping. Fix that. Using pr_cont() again would be a solution, but the commit explicitly removed its use. Avoiding the danger of mixing up split lines from multiple CPUs might be beneficial for near-panic dumps like this, so fix this without reintroducing pr_cont(). Reported-by: Anshuman Khandual Reported-by: Michal Hocko Fixes: 76a1850e4572 ("mm/debug.c: __dump_page() prints an extra line") Signed-off-by: Vlastimil Babka --- mm/debug.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/mm/debug.c b/mm/debug.c index 0461df1207cb..6a52316af839 100644 --- a/mm/debug.c +++ b/mm/debug.c @@ -47,6 +47,7 @@ void __dump_page(struct page *page, const char *reason) struct address_space *mapping; bool page_poisoned = PagePoisoned(page); int mapcount; + char *type = ""; /* * If struct page is poisoned don't access Page*() functions as that @@ -78,9 +79,9 @@ void __dump_page(struct page *page, const char *reason) page, page_ref_count(page), mapcount, page->mapping, page_to_pgoff(page)); if (PageKsm(page)) - pr_warn("ksm flags: %#lx(%pGp)\n", page->flags, &page->flags); + type = "ksm "; else if (PageAnon(page)) - pr_warn("anon flags: %#lx(%pGp)\n", page->flags, &page->flags); + type = "anon "; else if (mapping) { if (mapping->host && mapping->host->i_dentry.first) { struct dentry *dentry; @@ -88,10 +89,11 @@ void __dump_page(struct page *page, const char *reason) pr_warn("%ps name:\"%pd\"\n", mapping->a_ops, dentry); } else pr_warn("%ps\n", mapping->a_ops); - pr_warn("flags: %#lx(%pGp)\n", page->flags, &page->flags); } BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS + 1); + pr_warn("%sflags: %#lx(%pGp)\n", type, page->flags, &page->flags); + hex_only: print_hex_dump(KERN_WARNING, "raw: ", DUMP_PREFIX_NONE, 32, sizeof(unsigned long), page, -- 2.24.1