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 ABC1BC433DB for ; Wed, 10 Mar 2021 20:56:16 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EE52064FCA for ; Wed, 10 Mar 2021 20:56:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EE52064FCA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 370488D020C; Wed, 10 Mar 2021 15:56:15 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 31F9F8D01ED; Wed, 10 Mar 2021 15:56:15 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 19A308D020C; Wed, 10 Mar 2021 15:56:15 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0022.hostedemail.com [216.40.44.22]) by kanga.kvack.org (Postfix) with ESMTP id EC5838D01ED for ; Wed, 10 Mar 2021 15:56:14 -0500 (EST) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id B1121181AEF1D for ; Wed, 10 Mar 2021 20:56:14 +0000 (UTC) X-FDA: 77905172268.17.E209F25 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf09.hostedemail.com (Postfix) with ESMTP id 281966000104 for ; Wed, 10 Mar 2021 20:56:10 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 9997564EE8; Wed, 10 Mar 2021 20:56:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1615409771; bh=VVx5ZS51pRRZ4Kk2g9iYDAMVtDpyywK24kFljFq/lUE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Pzd+NJwuI3bJfWQoBjUnXiggyLHtJjbt1dV+HJlQTLJ5cOrrBcNgrYCW4N6QeG6kb AbnC9hY/E8KQY6uIupWFP1khFCouvNWf7Du3EzMJ7L1cJzMLPWUq1vTqGvDz/W9aE0 YVWQBNKZSu7dU3x+Gbcprv7XSNRkDkzPdiAMTtM4= Date: Wed, 10 Mar 2021 12:56:09 -0800 From: Andrew Morton To: Minchan Kim Cc: linux-mm , LKML , John Dias , Michal Hocko , David Hildenbrand , Jason Baron Subject: Re: [PATCH v3] mm: page_alloc: dump migrate-failed pages Message-Id: <20210310125609.359888dc65562fbed4b1f088@linux-foundation.org> In-Reply-To: <20210310180104.517886-1-minchan@kernel.org> References: <20210310180104.517886-1-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 X-Stat-Signature: qkfi7ouuuma4ma8ac5hdspojkpwptnqw X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 281966000104 Received-SPF: none (linux-foundation.org>: No applicable sender policy available) receiver=imf09; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1615409770-502128 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 Wed, 10 Mar 2021 10:01:04 -0800 Minchan Kim wrote: > Currently, debugging CMA allocation failures is quite limited. > The most commong source of these failures seems to be page > migration which doesn't provide any useful information on the > reason of the failure by itself. alloc_contig_range can report > those failures as it holds a list of migrate-failed pages. > > 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. > > The reason it approach with dynamic debug is the debug message > could emit lots of noises as alloc_contig_range calls more > frequently since it's a best effort allocator. > > There are two ifdefery conditions to support common dyndbg options: > > - CONFIG_DYNAMIC_DEBUG_CORE && DYNAMIC_DEBUG_MODULE > It aims for supporting the feature with only specific file > with adding ccflags. > > - CONFIG_DYNAMIC_DEBUG > It aims for supporting the feature with system wide globally. > > A simple example to enable the feature: > > 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 I think the changelog is out of sync. Did you mean "alloc_contig_dump_pages" here? > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -8453,6 +8453,27 @@ 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 void alloc_contig_dump_pages(struct list_head *page_list) > +{ > + DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, > + "migrate failure"); > + > + if (DYNAMIC_DEBUG_BRANCH(descriptor)) { > + struct page *page; > + > + WARN(1, "failed callstack"); > + list_for_each_entry(page, page_list, lru) > + dump_page(page, "migration failure"); > + } > +} I doubt if everyone is familiar with dynamic debug. It might be kind to add a little comment over this, telling people how to turn it on and off.