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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 6D4D3C43381 for ; Tue, 9 Mar 2021 00:22:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 30A3264EEB for ; Tue, 9 Mar 2021 00:22:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232105AbhCIAVx (ORCPT ); Mon, 8 Mar 2021 19:21:53 -0500 Received: from mail.kernel.org ([198.145.29.99]:48232 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231864AbhCIAVb (ORCPT ); Mon, 8 Mar 2021 19:21:31 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id DD52C64FFD; Tue, 9 Mar 2021 00:21:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1615249289; bh=DlBHQTYx7AJjClppLF+twkS9JNHiruHKDw5scvY5BrA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=bz4V75JpPXo1KIN+GkM4xn8NkmqewhCdNlKTr+cJK/BdQsFf98dTcK+7z1R+DP81R 5AcnE/X7h1rlyY07XBIzIE5udXa8itnYRkvfj664sPVLvixjCHP8yGtmg8unzPvWRJ 7F5c0pCJiBLFkS8nUwozNkTIWnPsmhTZRudFJFfA= Date: Mon, 8 Mar 2021 16:21:28 -0800 From: Andrew Morton To: Minchan Kim Cc: linux-mm , LKML , John Dias , Michal Hocko , David Hildenbrand , Jason Baron Subject: Re: [PATCH v2] mm: page_alloc: dump migrate-failed pages Message-Id: <20210308162128.9b4a7d4c1576a72fd4878bdb@linux-foundation.org> In-Reply-To: <20210308202047.1903802-1-minchan@kernel.org> References: <20210308202047.1903802-1-minchan@kernel.org> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 8 Mar 2021 12:20:47 -0800 Minchan Kim wrote: > alloc_contig_range is usually used on cma area or movable zone. > It's critical if the page migration fails on those areas so > dump more debugging message. > > page refcount, mapcount with page flags on dump_page are > helpful information to deduce the culprit. Furthermore, > dump_page_owner was super helpful to find long term pinner > who initiated the page allocation. > > Admin could enable the dump like this(by default, disabled) > > echo "func dump_migrate_failure_pages +p" > control > > Admin could disable it. > > echo "func dump_migrate_failure_pages =_" > control > > ... > > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -8453,6 +8453,34 @@ static unsigned long pfn_max_align_up(unsigned long pfn) > pageblock_nr_pages)); > } > > +#if defined(CONFIG_DYNAMIC_DEBUG) || \ > + (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE)) > +static DEFINE_RATELIMIT_STATE(alloc_contig_ratelimit_state, > + DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); > +int alloc_contig_ratelimit(void) > +{ > + return __ratelimit(&alloc_contig_ratelimit_state); > +} Wow, that's an eyesore. We're missing helpers in the ratelimit code. Can we do something like /* description goes here */ #define RATELIMIT2(interval, burst) ({ static DEFINE_RATELIMIT_STATE(_rs, interval, burst); __ratelimit(_rs); }) #define RATELIMIT() RATELIMIT2(DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST) > +void dump_migrate_failure_pages(struct list_head *page_list) > +{ > + DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, > + "migrate failure"); > + if (DYNAMIC_DEBUG_BRANCH(descriptor) && > + alloc_contig_ratelimit()) { > + struct page *page; > + > + WARN(1, "failed callstack"); > + list_for_each_entry(page, page_list, lru) > + dump_page(page, "migration failure"); > + } > +} Then we can simply do if (DYNAMIC_DEBUG_BRANCH(descriptor) && RATELIMIT())