linux-kernel - Re: [-mm PATCH] register_memory/unregister

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Message-ID: <20080211203508.GA6159@kroah.com>
Date:	Mon, 11 Feb 2008 12:35:08 -0800
From:	Greg KH <greg@...ah.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Badari Pulavarty <pbadari@...ibm.com>,
	linux-kernel@...r.kernel.org, haveblue@...ibm.com,
	linux-mm@...ck.org
Subject: Re: [-mm PATCH] register_memory/unregister_memory clean ups

On Mon, Feb 11, 2008 at 11:48:18AM -0800, Andrew Morton wrote:
> On Mon, 11 Feb 2008 09:23:18 -0800
> Badari Pulavarty <pbadari@...ibm.com> wrote:
> 
> > Hi Andrew,
> > 
> > While testing hotplug memory remove against -mm, I noticed
> > that unregister_memory() is not cleaning up /sysfs entries
> > correctly. It also de-references structures after destroying
> > them (luckily in the code which never gets used). So, I cleaned
> > up the code and fixed the extra reference issue.
> > 
> > Could you please include it in -mm ?
> > 
> > Thanks,
> > Badari
> > 
> > register_memory()/unregister_memory() never gets called with
> > "root". unregister_memory() is accessing kobject_name of
> > the object just freed up. Since no one uses the code,
> > lets take the code out. And also, make register_memory() static.  
> > 
> > Another bug fix - before calling unregister_memory()
> > remove_memory_block() gets a ref on kobject. unregister_memory()
> > need to drop that ref before calling sysdev_unregister().
> > 
> 
> I'd say this:
> 
> > Subject: [-mm PATCH] register_memory/unregister_memory clean ups
> 
> is rather tame.  These are more than cleanups!  These sound like
> machine-crashing bugs.  Do they crash machines?  How come nobody noticed
> it?
> 
> All very strange...

No one has ever run the 'remove memory' codepath before, that's why they
were never seen before :)

thanks,

greg k-h
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