linux-kernel - Re: [PATCH] sparsemem: BUILD_BUG_ON when sizeof mem

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Message-ID: <51A7A5F3.4040704@sr71.net>
Date:	Thu, 30 May 2013 12:18:11 -0700
From:	Dave Hansen <dave@...1.net>
To:	Cody P Schafer <cody@...ux.vnet.ibm.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux MM <linux-mm@...ck.org>,
	David Hansen <dave.hansen@...el.com>
Subject: Re: [PATCH] sparsemem: BUILD_BUG_ON when sizeof mem_section is non-power-of-2

On 05/30/2013 11:40 AM, Cody P Schafer wrote:
> Instead of leaving a hidden trap for the next person who comes along and
> wants to add something to mem_section, add a big fat warning about it
> needing to be a power-of-2, and insert a BUILD_BUG_ON() in sparse_init()
> to catch mistakes.
> 
> Right now non-power-of-2 mem_sections cause a number of WARNs at boot
> (which don't clearly point to the size of mem_section as an issue), but
> the system limps on (temporarily, at least).
> 
> This is based upon Dave Hansen's earlier RFC where he ran into the same
> issue:
> 	"sparsemem: fix boot when SECTIONS_PER_ROOT is not power-of-2"
> 	http://lkml.indiana.edu/hypermail/linux/kernel/1205.2/03077.html

Thanks for doing that, Cody.  At the risk of patting myself on the back:

Acked-by: Dave Hansen <dave.hansen@...ux.intel.com>
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