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Subject: Re: [PATCH] break_lock forever broken
From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Hugh Dickins <hugh@veritas.com>
Cc: Andrew Morton <akpm@osdl.org>, Ingo Molnar <mingo@elte.hu>,
       lkml <linux-kernel@vger.kernel.org>
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Date: Mon, 14 Mar 2005 16:01:42 +1100
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On Sat, 2005-03-12 at 23:20 +0000, Hugh Dickins wrote:

> Since cond_resched_lock's spin_lock clears break_lock, no need to clear it
> itself; and use need_lockbreak there too, preferring optimizer to #ifdefs.
> 

FWIW, this patch solves the problems I had in mind (and so should
solve our copy_page_range livelock I hope). I was sort of inclined
to clear break_lock at lock time too.

As Arjan points out, an unconditional set is probably the way to go
if we've already dirtied the cacheline.

> Signed-off-by: Hugh Dickins <hugh@veritas.com>
> 

Thanks for doing the patch Hugh.