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Subject: Re: [patch] mm: tiny-shmem fix lor, mmap_sem vs i_mutex
From: Dave Hansen <dave@linux.vnet.ibm.com>
To: Matt Mackall <mpm@selenic.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>, Ingo Molnar <mingo@elte.hu>,
       Andrew Morton <akpm@linux-foundation.org>,
       Nick Piggin <npiggin@suse.de>, a.p.zijlstra@chello.nl,
       linux-kernel@vger.kernel.org, Hugh Dickins <hugh@veritas.com>,
       Dave Hansen <haveblue@us.ibm.com>
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Date: Fri, 19 Sep 2008 19:18:39 -0700
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On Thu, 2008-09-18 at 14:11 -0700, Matt Mackall wrote:
> On Thu, 2008-09-18 at 12:29 -0700, Jeremy Fitzhardinge wrote:
> > Ingo Molnar wrote:
> > > in 7 days that's about 7000 random bootups, 20% of which had TINY_SHMEM 
> > > enabled, half 32-bit, half 64-bit x86. It did not blow up in any way 
> > > that would have prevented the kernel from building its next random 
> > > version from within itself and it did not produce any kernel messages 
> > > with various random kernel debug, compile and boot options.
> > >   
> > 
> > Does anything in that workload actually use shared memory?
> 
> [adding Dave]
> 
> For the record, Hugh tracked down the history of this bug and it went
> something like this:
> 
> - I forked shmem.c and trimmed it down, keeping the function in question
> intact
> - Dave Hansen made divergent changes to shmem and tiny-shmem for reasons
> that aren't immediately obvious

Man, my memory sucks.  All I see that 'git blame' can pin on me are some
of the i_nlink helper additions.  Those weren't made in tiny-shmem.c
simply because it doesn't manipulate i_nlink like shmem.c does.  Was
there something else you had in mind?

-- Dave