From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f199.google.com (mail-qt0-f199.google.com [209.85.216.199]) by kanga.kvack.org (Postfix) with ESMTP id E2DB46B0003 for ; Wed, 27 Jun 2018 18:59:51 -0400 (EDT) Received: by mail-qt0-f199.google.com with SMTP id b8-v6so3496232qto.13 for ; Wed, 27 Jun 2018 15:59:51 -0700 (PDT) Received: from mx1.redhat.com (mx3-rdu2.redhat.com. [66.187.233.73]) by mx.google.com with ESMTPS id u43-v6si2640199qtk.112.2018.06.27.15.59.50 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 27 Jun 2018 15:59:50 -0700 (PDT) Date: Thu, 28 Jun 2018 06:59:45 +0800 From: Baoquan He Subject: Re: [PATCH v5 2/4] mm/sparsemem: Defer the ms->section_mem_map clearing Message-ID: <20180627225945.GD8970@localhost.localdomain> References: <20180627013116.12411-1-bhe@redhat.com> <20180627013116.12411-3-bhe@redhat.com> <20180627095439.GA5924@techadventures.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180627095439.GA5924@techadventures.net> Sender: owner-linux-mm@kvack.org List-ID: To: Oscar Salvador Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, dave.hansen@intel.com, pagupta@redhat.com, linux-mm@kvack.org, kirill.shutemov@linux.intel.com On 06/27/18 at 11:54am, Oscar Salvador wrote: > On Wed, Jun 27, 2018 at 09:31:14AM +0800, Baoquan He wrote: > > In sparse_init(), if CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER=y, system > > will allocate one continuous memory chunk for mem maps on one node and > > populate the relevant page tables to map memory section one by one. If > > fail to populate for a certain mem section, print warning and its > > ->section_mem_map will be cleared to cancel the marking of being present. > > Like this, the number of mem sections marked as present could become > > less during sparse_init() execution. > > > > Here just defer the ms->section_mem_map clearing if failed to populate > > its page tables until the last for_each_present_section_nr() loop. This > > is in preparation for later optimizing the mem map allocation. > > > > Signed-off-by: Baoquan He > > --- > > mm/sparse-vmemmap.c | 1 - > > mm/sparse.c | 12 ++++++++---- > > 2 files changed, 8 insertions(+), 5 deletions(-) > > > > diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c > > index bd0276d5f66b..640e68f8324b 100644 > > --- a/mm/sparse-vmemmap.c > > +++ b/mm/sparse-vmemmap.c > > @@ -303,7 +303,6 @@ void __init sparse_mem_maps_populate_node(struct page **map_map, > > ms = __nr_to_section(pnum); > > pr_err("%s: sparsemem memory map backing failed some memory will not be available\n", > > __func__); > > - ms->section_mem_map = 0; > > Since we are deferring the clearing of section_mem_map, I guess we do not need > > struct mem_section *ms; > ms = __nr_to_section(pnum); > > anymore, right? Right, good catch, thanks. I will post a new round to fix this. > > > } > > > > if (vmemmap_buf_start) { > > diff --git a/mm/sparse.c b/mm/sparse.c > > index 6314303130b0..71ad53da2cd1 100644 > > --- a/mm/sparse.c > > +++ b/mm/sparse.c > > @@ -451,7 +451,6 @@ void __init sparse_mem_maps_populate_node(struct page **map_map, > > ms = __nr_to_section(pnum); > > pr_err("%s: sparsemem memory map backing failed some memory will not be available\n", > > __func__); > > - ms->section_mem_map = 0; > > The same goes here. > > > > -- > Oscar Salvador > SUSE L3