linux-kernel - Re: vm_unmap

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Message-ID: <4906C789.7060408@goop.org>
Date:	Tue, 28 Oct 2008 19:04:25 +1100
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Nick Piggin <nickpiggin@...oo.com.au>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux Memory Management List <linux-mm@...ck.org>
Subject: Re: vm_unmap_aliases and Xen

Nick Piggin wrote:
> On Friday 24 October 2008 10:48, Jeremy Fitzhardinge wrote:
>   
>> I've been having a few problems with Xen, I suspect as a result of the
>> lazy unmapping in vmalloc.c.
>>
>> One immediate one is that vm_unmap_aliases() will oops if you call it
>> before vmalloc_init() is called, which can happen in the Xen case.  RFC
>> patch below.
>>     
>
> Sure, we could do that. If you add an unlikely, and a __read_mostly,
> I'd ack it. Thanks for picking this up.
>   

OK, will respin accordingly.

>> But the bigger problem I'm seeing is that despite calling
>> vm_unmap_aliases() at the pertinent places, I'm still seeing errors
>> resulting from stray aliases.  Is it possible that vm_unmap_aliases()
>> could be missing some, or not completely synchronous?
>>     
>
> It's possible, but of course that would not be by design ;)
>
> I've had another look over it, and nothing obvious comes to
> mind.
>   

I found the problem and fixed it; I was just doing the operations in the 
wrong order.

Thanks,
    J
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