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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 33761C433E0 for ; Mon, 1 Feb 2021 10:13:37 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 758E264DB2 for ; Mon, 1 Feb 2021 10:13:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 758E264DB2 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 C6C266B0006; Mon, 1 Feb 2021 05:13:35 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C1EFA6B006C; Mon, 1 Feb 2021 05:13:35 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B32D16B006E; Mon, 1 Feb 2021 05:13:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0008.hostedemail.com [216.40.44.8]) by kanga.kvack.org (Postfix) with ESMTP id 9D6476B0006 for ; Mon, 1 Feb 2021 05:13:35 -0500 (EST) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 62213181AEF10 for ; Mon, 1 Feb 2021 10:13:35 +0000 (UTC) X-FDA: 77769287190.16.women41_1c04a46275c1 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin16.hostedemail.com (Postfix) with ESMTP id 3E755100E690C for ; Mon, 1 Feb 2021 10:13:35 +0000 (UTC) X-HE-Tag: women41_1c04a46275c1 X-Filterd-Recvd-Size: 4315 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf39.hostedemail.com (Postfix) with ESMTP for ; Mon, 1 Feb 2021 10:13:34 +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 E901BACB0; Mon, 1 Feb 2021 10:13:32 +0000 (UTC) Subject: Re: [PATCH] mm/page_owner: Record the timestamp of all pages during free To: Georgi Djakov , akpm@linux-foundation.org, linux-mm@kvack.org Cc: corbet@lwn.net, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org References: <20210129234548.10054-1-georgi.djakov@linaro.org> From: Vlastimil Babka Message-ID: <735983e1-f439-8e77-7959-135164c517ed@suse.cz> Date: Mon, 1 Feb 2021 11:13:31 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: <20210129234548.10054-1-georgi.djakov@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 1/30/21 12:45 AM, Georgi Djakov wrote: > Collect the time when each allocation is freed, to help with memory > analysis with kdump/ramdump. > > Having another timestamp when we free the page helps for debugging > page migration issues. For example both alloc and free timestamps > being the same can gave hints that there is an issue with migrating > memory, as opposed to a page just being dropped during migration. Besides crash dump analysis, we should also provide this timestamp in the page_owner file and dump_page()? > Signed-off-by: Georgi Djakov > --- > Documentation/vm/page_owner.rst | 2 +- > mm/page_owner.c | 5 +++++ > 2 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/Documentation/vm/page_owner.rst b/Documentation/vm/page_owner.rst > index 4e67c2e9bbed..5d7a62c2be28 100644 > --- a/Documentation/vm/page_owner.rst > +++ b/Documentation/vm/page_owner.rst > @@ -47,7 +47,7 @@ size change due to this facility. > > text data bss dec hex filename > 48800 2445 644 51889 cab1 mm/page_alloc.o > - 6574 108 29 6711 1a37 mm/page_owner.o > + 6644 108 29 6777 1a79 mm/page_owner.o > 1025 8 8 1041 411 mm/page_ext.o > > Although, roughly, 8 KB code is added in total, page_alloc.o increase by > diff --git a/mm/page_owner.c b/mm/page_owner.c > index d15c7c4994f5..fbdf064e7494 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -27,6 +27,7 @@ struct page_owner { > depot_stack_handle_t handle; > depot_stack_handle_t free_handle; > u64 ts_nsec; > + u64 free_ts_nsec; > pid_t pid; > }; > > @@ -148,6 +149,7 @@ void __reset_page_owner(struct page *page, unsigned int order) > struct page_ext *page_ext; > depot_stack_handle_t handle = 0; > struct page_owner *page_owner; > + u64 free_ts_nsec = local_clock(); > > handle = save_stack(GFP_NOWAIT | __GFP_NOWARN); > > @@ -158,6 +160,7 @@ void __reset_page_owner(struct page *page, unsigned int order) > __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags); > page_owner = get_page_owner(page_ext); > page_owner->free_handle = handle; > + page_owner->free_ts_nsec = free_ts_nsec; > page_ext = page_ext_next(page_ext); > } > } > @@ -177,6 +180,7 @@ static inline void __set_page_owner_handle(struct page *page, > page_owner->last_migrate_reason = -1; > page_owner->pid = current->pid; > page_owner->ts_nsec = local_clock(); > + page_owner->free_ts_nsec = 0; Might be more useful not to reset the time of previous free when the page is reallocated? > __set_bit(PAGE_EXT_OWNER, &page_ext->flags); > __set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags); > > @@ -243,6 +247,7 @@ void __copy_page_owner(struct page *oldpage, struct page *newpage) > new_page_owner->handle = old_page_owner->handle; > new_page_owner->pid = old_page_owner->pid; > new_page_owner->ts_nsec = old_page_owner->ts_nsec; > + new_page_owner->free_ts_nsec = old_page_owner->ts_nsec; > > /* > * We don't clear the bit on the oldpage as it's going to be freed >