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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 1ED98C433B4 for ; Wed, 7 Apr 2021 22:47:17 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8160861245 for ; Wed, 7 Apr 2021 22:47:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8160861245 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gentoo.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id F22E26B0073; Wed, 7 Apr 2021 18:47:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EFB586B0078; Wed, 7 Apr 2021 18:47:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DE8DB6B007D; Wed, 7 Apr 2021 18:47:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0199.hostedemail.com [216.40.44.199]) by kanga.kvack.org (Postfix) with ESMTP id C27976B0073 for ; Wed, 7 Apr 2021 18:47:15 -0400 (EDT) Received: from smtpin34.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 7685B8777 for ; Wed, 7 Apr 2021 22:47:15 +0000 (UTC) X-FDA: 78007058430.34.9AEEC04 Received: from smtp.gentoo.org (smtp.gentoo.org [140.211.166.183]) by imf11.hostedemail.com (Postfix) with ESMTP id B7F7B200024C for ; Wed, 7 Apr 2021 22:47:09 +0000 (UTC) Received: by sf.home (Postfix, from userid 1000) id 708AD5A22061; Wed, 7 Apr 2021 23:47:08 +0100 (BST) Date: Wed, 7 Apr 2021 23:47:08 +0100 From: Sergei Trofimovich To: Vlastimil Babka Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] mm: page_owner: fetch backtrace only for tracked pages Message-ID: References: <20210401212445.3534721-1-slyfox@gentoo.org> <0c18e497-07d1-887f-e49e-b6315f396ab8@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0c18e497-07d1-887f-e49e-b6315f396ab8@suse.cz> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: B7F7B200024C X-Stat-Signature: h8p4tar65hiyh73uwqioi3tbcwh5gpe3 Received-SPF: none (gentoo.org>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=smtp.gentoo.org; client-ip=140.211.166.183 X-HE-DKIM-Result: none/none X-HE-Tag: 1617835629-271226 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, Apr 07, 2021 at 05:49:14PM +0200, Vlastimil Babka wrote: > On 4/1/21 11:24 PM, Sergei Trofimovich wrote: > > Very minor optimization. > > I'm not entirely sure about accuracy of "only for tracked pages". Missing > page_ext is something I'm not even sure how possible it is in practice, probably > just an error condition (failed to be allocated?). Or did you observe this in > practice? But anyway, the change is not wrong. Never saw missing 'page_ext' in practice (I also did not check for it explicitly). I agree "optimization" is misleading. "cleanup" might be a better wording. > > CC: Andrew Morton > > CC: linux-mm@kvack.org > > Signed-off-by: Sergei Trofimovich > > Acked-by: Vlastimil Babka > > > --- > > mm/page_owner.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/mm/page_owner.c b/mm/page_owner.c > > index 63e4ecaba97b..7147fd34a948 100644 > > --- a/mm/page_owner.c > > +++ b/mm/page_owner.c > > @@ -140,14 +140,14 @@ void __reset_page_owner(struct page *page, unsigned int order) > > { > > int i; > > struct page_ext *page_ext; > > - depot_stack_handle_t handle = 0; > > + depot_stack_handle_t handle; > > struct page_owner *page_owner; > > > > - handle = save_stack(GFP_NOWAIT | __GFP_NOWARN); > > - > > page_ext = lookup_page_ext(page); > > if (unlikely(!page_ext)) > > return; > > + > > + handle = save_stack(GFP_NOWAIT | __GFP_NOWARN); > > for (i = 0; i < (1 << order); i++) { > > __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags); > > page_owner = get_page_owner(page_ext); > > > -- Sergei