From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f197.google.com (mail-wr0-f197.google.com [209.85.128.197]) by kanga.kvack.org (Postfix) with ESMTP id D63366B038C for ; Thu, 16 Mar 2017 05:17:21 -0400 (EDT) Received: by mail-wr0-f197.google.com with SMTP id y90so7360052wrb.1 for ; Thu, 16 Mar 2017 02:17:21 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id h19si5855114wrc.138.2017.03.16.02.17.20 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 16 Mar 2017 02:17:20 -0700 (PDT) Date: Thu, 16 Mar 2017 10:17:18 +0100 From: Michal Hocko Subject: Re: + mm-sparse-refine-usemap_size-a-little.patch added to -mm tree Message-ID: <20170316091718.GA30508@dhcp22.suse.cz> References: <58c32b92.qgOCFj/bIjx+ym6m%akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <58c32b92.qgOCFj/bIjx+ym6m%akpm@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: richard.weiyang@gmail.com, tj@kernel.org, mm-commits@vger.kernel.org, Mel Gorman , linux-mm@kvack.org [CC Mel] On Fri 10-03-17 14:41:22, Andrew Morton wrote: > From: Wei Yang > Subject: mm/sparse: refine usemap_size() a little > > Current implementation calculates usemap_size in two steps: > * calculate number of bytes to cover these bits > * calculate number of "unsigned long" to cover these bytes > > It would be more clear by: > * calculate number of "unsigned long" to cover these bits > * multiple it with sizeof(unsigned long) > > This patch refine usemap_size() a little to make it more easy to > understand. I haven't checked deeply yet but reading through 5c0e3066474b ("Fix corruption of memmap on IA64 SPARSEMEM when mem_section is not a power of 2") made me ask whether the case described in the commit message still applies after this change or whether it has been considered at all. > Link: http://lkml.kernel.org/r/20170310043713.96871-1-richard.weiyang@gmail.com > Signed-off-by: Wei Yang > Cc: Tejun Heo > Signed-off-by: Andrew Morton > --- > > mm/sparse.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > diff -puN mm/sparse.c~mm-sparse-refine-usemap_size-a-little mm/sparse.c > --- a/mm/sparse.c~mm-sparse-refine-usemap_size-a-little > +++ a/mm/sparse.c > @@ -248,10 +248,7 @@ static int __meminit sparse_init_one_sec > > unsigned long usemap_size(void) > { > - unsigned long size_bytes; > - size_bytes = roundup(SECTION_BLOCKFLAGS_BITS, 8) / 8; > - size_bytes = roundup(size_bytes, sizeof(unsigned long)); > - return size_bytes; > + return BITS_TO_LONGS(SECTION_BLOCKFLAGS_BITS) * sizeof(unsigned long); > } > > #ifdef CONFIG_MEMORY_HOTPLUG > _ > > Patches currently in -mm which might be from richard.weiyang@gmail.com are > > mm-sparse-refine-usemap_size-a-little.patch > mm-page_alloc-return-0-in-case-this-node-has-no-page-within-the-zone.patch > > -- > To unsubscribe from this list: send the line "unsubscribe mm-commits" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org