From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] mm: create a separate slab for page->ptl allocation
Date: Wed, 6 Nov 2013 12:02:00 +0100
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To: Will Deacon <will.deacon@arm.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>, Andrew Morton <akpm@linux-foundation.org>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>, Ingo Molnar <mingo@redhat.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>

On Wed, Nov 06, 2013 at 10:34:03AM +0000, Will Deacon wrote:
> FWIW: if the architecture selects ARCH_USE_CMPXCHG_LOCKREF, then a spinlock_t
> is 32-bit (assuming that unsigned int is also 32-bit).

Egads, talk about fragile. That thing relies on someone actually keeping
lib/Kconfig up-to-date.