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=-8.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 72D80C432C1 for ; Tue, 24 Sep 2019 11:31:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 45A72214DA for ; Tue, 24 Sep 2019 11:31:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=shutemov-name.20150623.gappssmtp.com header.i=@shutemov-name.20150623.gappssmtp.com header.b="l3SZNumX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2504719AbfIXLbh (ORCPT ); Tue, 24 Sep 2019 07:31:37 -0400 Received: from mail-ed1-f67.google.com ([209.85.208.67]:46314 "EHLO mail-ed1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389832AbfIXLbh (ORCPT ); Tue, 24 Sep 2019 07:31:37 -0400 Received: by mail-ed1-f67.google.com with SMTP id t3so1470590edw.13 for ; Tue, 24 Sep 2019 04:31:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=0s5uYaNwj5xj6xYoxNOhC3OaXLMlVBvmApGp6ZZlckg=; b=l3SZNumXspIFEaMls1NecrGdIl6Ry+IRhRWMzsFzupD0fH0NHJ7VLDRB34lS0ldE7N ndbhQYf1ICl9fSCpzFNgQLuVcEJ+Np1jWL1nlP/Ia5G7ZsoW+3quKW0HRD+sA4yZbfKv FQi8y+0knNTKY1fme3FR8O1IgEJa0Sslu0mdfi1yESAjl0MzgIp/Y8P8x/sgeh6ZxSVx AN/W5IKyG2DWvgDmkGgCW5dlVcKH6VGo9P0NCMtpCbv5wPp6XtuvHQyvyp9x4hqPPTWz d74lvyP9UCmG/W3gY+KYgAUjckR945mqb2iEqP/ISWT4AxfzKR/HdN349nxlNzG71XRc W67A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=0s5uYaNwj5xj6xYoxNOhC3OaXLMlVBvmApGp6ZZlckg=; b=Wdpgkmytx635YbcDE48pvJw13F9Xi0w3ULcSgIipMC5SsYZgkP5B/50PjznqMhHIjR peEZ5B1tixirJmPLk/IEg9IGP9jhXrbjDk4yU92mgof4W306eKW2IRkUZQmZ3NSegECm fpwAK40l8FP05fxRjARFwgU83+vJSh7EMz33PBwtFG1F42JPlgARA+Uktxqa5AAHiIX7 gVgUDrzn58jV7WnbvO2F4Q7gx++JKyM6ENR+w2BZxSVnS3tj86ee709nE8IFIvUeO2F6 nBnfa9NM81q4GlVJHbOyMn/faucUfzArJxxYsEeCGG/1i4DIymOiyRf8dNxrwvW6R8RC INdA== X-Gm-Message-State: APjAAAUzBbDL8XqK1KN73JVQFKwYcqSR0xVnTUTb/yYWdL5WJZGRMS2a cY5bP+DODtb40DUOwNrs50Mjr6k1Li0= X-Google-Smtp-Source: APXvYqxtjktaC/U2yewI61ivQK1f6jLxNDhyr3uUo3Rjj/tslZy6jVYSP1ngpvQNdCvJd9RSzlf0Cg== X-Received: by 2002:aa7:ce88:: with SMTP id y8mr2151323edv.145.1569324695442; Tue, 24 Sep 2019 04:31:35 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id g17sm178398ejb.80.2019.09.24.04.31.34 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 24 Sep 2019 04:31:34 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 014CC1022A6; Tue, 24 Sep 2019 14:31:35 +0300 (+03) Date: Tue, 24 Sep 2019 14:31:35 +0300 From: "Kirill A. Shutemov" To: Vlastimil Babka Cc: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org, "Kirill A. Shutemov" , Michal Hocko , Mel Gorman , Matthew Wilcox Subject: Re: [PATCH v2 2/4] mm, page_owner: record page owner for each subpage Message-ID: <20190924113135.2ekb7bmil3rxge6w@box> References: <20190820131828.22684-1-vbabka@suse.cz> <20190820131828.22684-3-vbabka@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190820131828.22684-3-vbabka@suse.cz> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 20, 2019 at 03:18:26PM +0200, Vlastimil Babka wrote: > Currently, page owner info is only recorded for the first page of a high-order > allocation, and copied to tail pages in the event of a split page. With the > plan to keep previous owner info after freeing the page, it would be benefical > to record page owner for each subpage upon allocation. This increases the > overhead for high orders, but that should be acceptable for a debugging option. > > The order stored for each subpage is the order of the whole allocation. This > makes it possible to calculate the "head" pfn and to recognize "tail" pages > (quoted because not all high-order allocations are compound pages with true > head and tail pages). When reading the page_owner debugfs file, keep skipping > the "tail" pages so that stats gathered by existing scripts don't get inflated. > > Signed-off-by: Vlastimil Babka > --- > mm/page_owner.c | 40 ++++++++++++++++++++++++++++------------ > 1 file changed, 28 insertions(+), 12 deletions(-) > > diff --git a/mm/page_owner.c b/mm/page_owner.c > index addcbb2ae4e4..813fcb70547b 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -154,18 +154,23 @@ static noinline depot_stack_handle_t save_stack(gfp_t flags) > return handle; > } > > -static inline void __set_page_owner_handle(struct page_ext *page_ext, > - depot_stack_handle_t handle, unsigned int order, gfp_t gfp_mask) > +static inline void __set_page_owner_handle(struct page *page, > + struct page_ext *page_ext, depot_stack_handle_t handle, > + unsigned int order, gfp_t gfp_mask) > { > struct page_owner *page_owner; > + int i; > > - page_owner = get_page_owner(page_ext); > - page_owner->handle = handle; > - page_owner->order = order; > - page_owner->gfp_mask = gfp_mask; > - page_owner->last_migrate_reason = -1; > + for (i = 0; i < (1 << order); i++) { > + page_owner = get_page_owner(page_ext); > + page_owner->handle = handle; > + page_owner->order = order; > + page_owner->gfp_mask = gfp_mask; > + page_owner->last_migrate_reason = -1; > + __set_bit(PAGE_EXT_OWNER, &page_ext->flags); > > - __set_bit(PAGE_EXT_OWNER, &page_ext->flags); > + page_ext = lookup_page_ext(page + i); Isn't it off-by-one? You are calculating page_ext for the next page, right? And cant we just do page_ext++ here instead? > + } > } > > noinline void __set_page_owner(struct page *page, unsigned int order, > @@ -178,7 +183,7 @@ noinline void __set_page_owner(struct page *page, unsigned int order, > return; > > handle = save_stack(gfp_mask); > - __set_page_owner_handle(page_ext, handle, order, gfp_mask); > + __set_page_owner_handle(page, page_ext, handle, order, gfp_mask); > } > > void __set_page_owner_migrate_reason(struct page *page, int reason) > @@ -204,8 +209,11 @@ void __split_page_owner(struct page *page, unsigned int order) > > page_owner = get_page_owner(page_ext); > page_owner->order = 0; > - for (i = 1; i < (1 << order); i++) > - __copy_page_owner(page, page + i); > + for (i = 1; i < (1 << order); i++) { > + page_ext = lookup_page_ext(page + i); Again, page_ext++? > + page_owner = get_page_owner(page_ext); > + page_owner->order = 0; > + } > } > > void __copy_page_owner(struct page *oldpage, struct page *newpage) > @@ -483,6 +491,13 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) > > page_owner = get_page_owner(page_ext); > > + /* > + * Don't print "tail" pages of high-order allocations as that > + * would inflate the stats. > + */ > + if (!IS_ALIGNED(pfn, 1 << page_owner->order)) > + continue; > + > /* > * Access to page_ext->handle isn't synchronous so we should > * be careful to access it. > @@ -562,7 +577,8 @@ static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone) > continue; > > /* Found early allocated page */ > - __set_page_owner_handle(page_ext, early_handle, 0, 0); > + __set_page_owner_handle(page, page_ext, early_handle, > + 0, 0); > count++; > } > cond_resched(); > -- > 2.22.0 > > -- Kirill A. Shutemov