From: Peter Zijlstra <peterz@infradead.org>
To: Andrea Arcangeli <aarcange@redhat.com>
Cc: Avi Kivity <avi@redhat.com>, Thomas Gleixner <tglx@linutronix.de>,
Rik van Riel <riel@redhat.com>,
linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
Kent Overstreet <kent.overstreet@gmail.com>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: [COUNTERPATCH] mm: avoid overflowing preempt_count() in mmu_take_all_locks()
Date: Thu, 01 Apr 2010 18:12:34 +0200 [thread overview]
Message-ID: <1270138354.1598.99.camel@laptop> (raw)
In-Reply-To: <20100401154249.GQ5825@random.random>
On Thu, 2010-04-01 at 17:42 +0200, Andrea Arcangeli wrote:
> The ugliest part of it (that I think you missed below) is the breakage
> of the RCU locking in the anon-vma which requires adding refcounting
> to it. That was the worst part of the conversion as far as I can tell.
>
One thing we can do there is to mutex_trylock() if we get the lock, see
if we've got the right object, if the trylock fails we can do the
refcount thing and sleep. That would allow the fast-path to remain a
single atomic.
The only thing is growing that anon_vma struct, but KSM seems to already
do that for the most common .configs.
next prev parent reply other threads:[~2010-04-01 16:12 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-30 17:36 [PATCH] increase PREEMPT_BITS to 12 to avoid overflow when starting KVM Rik van Riel
2010-03-30 17:56 ` Peter Zijlstra
2010-03-30 18:05 ` Rik van Riel
2010-03-30 18:34 ` Peter Zijlstra
2010-04-01 9:40 ` [COUNTERPATCH] mm: avoid overflowing preempt_count() in mmu_take_all_locks() Avi Kivity
2010-04-01 10:31 ` Peter Zijlstra
2010-04-01 11:04 ` Thomas Gleixner
2010-04-01 11:13 ` Avi Kivity
2010-04-01 11:16 ` Peter Zijlstra
2010-04-01 11:19 ` Avi Kivity
2010-04-01 15:36 ` Andrea Arcangeli
2010-04-01 15:39 ` Avi Kivity
2010-04-01 15:54 ` Andrea Arcangeli
2010-04-01 16:02 ` Avi Kivity
2010-04-01 16:12 ` Andrea Arcangeli
2010-04-01 11:17 ` Avi Kivity
2010-04-01 11:27 ` Peter Zijlstra
2010-04-01 11:43 ` Peter Zijlstra
2010-04-01 11:47 ` Avi Kivity
2010-04-01 15:42 ` Andrea Arcangeli
2010-04-01 15:50 ` Peter Zijlstra
2010-04-01 15:56 ` Peter Zijlstra
2010-04-01 16:07 ` Andrea Arcangeli
2010-04-01 16:32 ` Peter Zijlstra
2010-04-01 16:00 ` Andrea Arcangeli
2010-04-01 15:51 ` Avi Kivity
2010-04-01 15:56 ` Peter Zijlstra
2010-04-01 16:06 ` Avi Kivity
2010-04-01 16:15 ` Paul E. McKenney
2010-04-01 16:36 ` Peter Zijlstra
2010-04-01 17:02 ` Paul E. McKenney
2010-04-01 16:08 ` Andrea Arcangeli
2010-04-01 16:14 ` Paul E. McKenney
2010-04-01 16:02 ` Andrea Arcangeli
2010-04-01 16:12 ` Peter Zijlstra [this message]
2010-04-01 16:18 ` Andrea Arcangeli
2010-04-01 16:45 ` Peter Zijlstra
2010-04-01 16:49 ` Peter Zijlstra
2010-04-01 17:04 ` Andrea Arcangeli
2010-04-01 14:16 ` Rik van Riel
2010-04-01 15:32 ` Andrea Arcangeli
2010-04-01 15:37 ` Avi Kivity
2010-04-01 11:09 ` Avi Kivity
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