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Subject: Re: [PATCH, REGRESSION v3] mm: make apply_to_page_range more robust
To: David Rientjes <rientjes@google.com>,
        =?UTF-8?Q?Mika_Penttil=c3=a4?= <mika.penttila@nextfour.com>
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 <alpine.DEB.2.10.1601211511230.9813@chino.kir.corp.google.com>
Cc: LKML <linux-kernel@vger.kernel.org>, linux-mm@kvack.org,
        Pekka Enberg <penberg@kernel.org>,
        Rusty Russell <rusty@rustcorp.com.au>
From: Pekka Enberg <penberg@iki.fi>
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Date: Fri, 22 Jan 2016 09:13:00 +0200
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On 01/22/2016 01:12 AM, David Rientjes wrote:
> NACK to your patch as it is just covering up buggy code silently. The 
> problem needs to be addressed in change_memory_common() to return if 
> there is no size to change (numpages == 0). It's a two line fix to 
> that function. 

So add a WARN_ON there to *warn* about the situations. There's really no 
need to BUG_ON here.

- Pekka