linux-kernel - Re: [PATCH v2] [BUGFIX] drivers/base: fix show_mem

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Date:	Tue, 27 Aug 2013 11:06:25 -0500
From:	Russ Anderson <rja@....com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
Subject: Re: [PATCH v2] [BUGFIX] drivers/base: fix show_mem_removable to
	handle missing sections

On Mon, Aug 26, 2013 at 02:49:59PM -0700, Andrew Morton wrote:
> On Fri, 23 Aug 2013 11:23:17 -0500 Russ Anderson <rja@....com> wrote:
> 
> > "cat /sys/devices/system/memory/memory*/removable" crashed the system.
> > 
> > The problem is that show_mem_removable() is passing a
> > bad pfn to is_mem_section_removable(), which causes
> > if (!node_online(page_to_nid(page))) to blow up.
> > Why is it passing in a bad pfn?
> > 
> > show_mem_removable() will loop sections_per_block times.
> > sections_per_block is 16, but mem->section_count is 8,
> > indicating holes in this memory block.  Checking that
> > the memory section is present before checking to see
> > if the memory section is removable fixes the problem.
> 
> The patch textually applies to 3.10, 3.9 and perhaps earlier.  Should
> it be applied to earlier kernels?

I believe so, since this does not appear to be a recent
regression, but have not verified the problem/fix in
earlier kernels.

Thanks,
-- 
Russ Anderson, OS RAS/Partitioning Project Lead  
SGI - Silicon Graphics Inc          rja@....com
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