Message-ID: <1406717571.9336.19.camel@buesod1.americas.hpqcorp.net>
Subject: Re: [PATCH] mm: BUG when __kmap_atomic_idx crosses boundary
From: Davidlohr Bueso <davidlohr@hp.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Chintan Pandya <cpandya@codeaurora.org>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org
Date: Wed, 30 Jul 2014 03:52:51 -0700
In-Reply-To: <1406716641.9336.17.camel@buesod1.americas.hpqcorp.net>
References: <1406710355-4360-1-git-send-email-cpandya@codeaurora.org>
	 <20140730020615.2f943cf7.akpm@linux-foundation.org>
	 <1406716641.9336.17.camel@buesod1.americas.hpqcorp.net>
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On Wed, 2014-07-30 at 03:37 -0700, Davidlohr Bueso wrote:
> On Wed, 2014-07-30 at 02:06 -0700, Andrew Morton wrote:
> > On Wed, 30 Jul 2014 14:22:35 +0530 Chintan Pandya <cpandya@codeaurora.org> wrote:
> > 
> > > __kmap_atomic_idx >= KM_TYPE_NR or < ZERO is a bug.
> > > Report it even if CONFIG_DEBUG_HIGHMEM is not enabled.
> > > That saves much debugging efforts.
> > 
> > Please take considerably more care when preparing patch changelogs.
> > 
> > kmap_atomic() is a very commonly called function so we'll need much
> > more detail than this to justify adding overhead to it.
> > 
> > I don't think CONFIG_DEBUG_HIGHMEM really needs to exist.  We could do
> > s/CONFIG_DEBUG_HIGHMEM/CONFIG_DEBUG_VM/g and perhaps your secret bug
> > whatever it was would have been found more easily.
> 
> Agreed, it would be nice to fold DEBUG_HIGHMEM into DEBUG_VM. However
> you'd still need some kind of intermediate option as DEBUG_VM must still
> exist if !HIGHMEM.

Actually no, it's a lot more straightforward than I thought.

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