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=-15.8 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=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 926C9C388F9 for ; Mon, 23 Nov 2020 14:13:59 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id F02692075A for ; Mon, 23 Nov 2020 14:13:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="kd7EHCER" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F02692075A Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 4C7A36B0089; Mon, 23 Nov 2020 09:13:58 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 478F36B0092; Mon, 23 Nov 2020 09:13:58 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 33FC06B0093; Mon, 23 Nov 2020 09:13:58 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0135.hostedemail.com [216.40.44.135]) by kanga.kvack.org (Postfix) with ESMTP id 0694F6B0089 for ; Mon, 23 Nov 2020 09:13:57 -0500 (EST) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 9F0721F10 for ; Mon, 23 Nov 2020 14:13:57 +0000 (UTC) X-FDA: 77515876914.02.page36_3d0b0c127366 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin02.hostedemail.com (Postfix) with ESMTP id 7F3E410097AA0 for ; Mon, 23 Nov 2020 14:13:57 +0000 (UTC) X-HE-Tag: page36_3d0b0c127366 X-Filterd-Recvd-Size: 3620 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf48.hostedemail.com (Postfix) with ESMTP for ; Mon, 23 Nov 2020 14:13:56 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1606140835; 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=ctnkZidQcbONL2E2GNXaD6vWwJeHp8xZUqynseoO/sA=; b=kd7EHCERweUSVilu2uB4nLfReLStHEYhuU1ziibqx0MG3I0FjP4Wt9AZ7rMZY6GOBfjwfM Zyl+pcYt1NmcZP6J6XfW76nkR6ZxVStM8Dd6qoDNOvKdiKRUEWvYY2UPbA3ZdWmrRwALyL nFUApIeWlgMH/omBSFYOZpv8XfH5Y1g= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 8A260AC23; Mon, 23 Nov 2020 14:13:55 +0000 (UTC) Date: Mon, 23 Nov 2020 15:13:54 +0100 From: Michal Hocko To: Charan Teja Reddy Cc: akpm@linux-foundation.org, david@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: memory_hotplug: put migration failure information under DEBUG_VM Message-ID: <20201123141354.GQ27488@dhcp22.suse.cz> References: <1606140196-6053-1-git-send-email-charante@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1606140196-6053-1-git-send-email-charante@codeaurora.org> 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 23-11-20 19:33:16, Charan Teja Reddy wrote: > When the pages are failed to get isolate or migrate, the page owner > information along with page info is dumped. If there are continuous > failures in migration(say page is pinned) or isolation, the log buffer > is simply getting flooded with the page owner information. As most of > the times page info is sufficient to know the causes for failures of > migration or isolation, place the page owner information under DEBUG_VM. I do not see why this path is any different from others that call dump_page. Page owner can add a very valuable information to debug the underlying reasons for failures here. It is an opt-in debugging feature which needs to be enabled explicitly. So I would argue users are ready to accept a lot of data in the kernel log. > Signed-off-by: Charan Teja Reddy > --- > mm/memory_hotplug.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 63b2e46..f48f30d 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1326,7 +1326,10 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) > > } else { > pr_warn("failed to isolate pfn %lx\n", pfn); > - dump_page(page, "isolation failed"); > + __dump_page(page, "isolation failed"); > +#if defined(CONFIG_DEBUG_VM) > + dump_page_owner(page); > +#endif > } > put_page(page); > } > @@ -1357,7 +1360,10 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) > list_for_each_entry(page, &source, lru) { > pr_warn("migrating pfn %lx failed ret:%d ", > page_to_pfn(page), ret); > - dump_page(page, "migration failure"); > + __dump_page(page, "migration failure"); > +#if defined(CONFIG_DEBUG_VM) > + dump_page_owner(page); > +#endif > } > putback_movable_pages(&source); > } > -- > QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a > member of the Code Aurora Forum, hosted by The Linux Foundation -- Michal Hocko SUSE Labs