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Message-ID: <483DBA85.2060502@cs.helsinki.fi>
Date: Wed, 28 May 2008 23:03:17 +0300
From: Pekka Enberg <penberg@cs.helsinki.fi>
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To: Paul Mundt <lethal@linux-sh.org>, LKML <linux-kernel@vger.kernel.org>,
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CC: akpm@linux-foundation.org, dhowells@redhat.com, mpm@selenic.com,
       clameter@sgi.com
Subject: Re: [PATCH] nommu: fix kobjsize() for SLOB and SLUB
References: <Pine.LNX.4.64.0805281646470.27125@sbz-30.cs.Helsinki.FI> <20080528153648.GA27783@linux-sh.org>
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(cc'ing linux-kernel)

Paul Mundt wrote:
> I have no idea why you are maintaining the page->index case here, it's
> completely broken for page cache pages. Unless someone more familiar with
> the page->index BUG_ON() tests objects, the BUG_ON() there should be
> removed completely. Neither Christoph nor I were able to work out what the
> point of the page->index tests were, and no one else has spoken up about
> them, so it's likely safe to treat them as bogus.

We use kobjsize() for pointers returned from do_mmap() which is why I 
kept the page->index case. Are we using PageCompound for those as well?

Paul Mundt wrote:
> SLOB on nommu will oops on any page cache page in the current git kernels
> until those BUG_ON()'s are killed. The more distressing thing is the fact
> that the blackfin people have been patching SLOB when it's obvious that
> they haven't been testing (ie, even booting!) it.

Hmm...