From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Hugh Dickins <hughd@google.com>
Cc: "Paul E. McKenney" <paul.mckenney@linaro.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: linux-next ppc64: RCU mods cause __might_sleep BUGs
Date: Thu, 03 May 2012 07:20:15 +1000 [thread overview]
Message-ID: <1335993615.4088.1.camel@pasglop> (raw)
In-Reply-To: <alpine.LSU.2.00.1205021324430.24246@eggly.anvils>
On Wed, 2012-05-02 at 13:25 -0700, Hugh Dickins wrote:
> Got it at last. Embarrassingly obvious. __rcu_read_lock() and
> __rcu_read_unlock() are not safe to be using __this_cpu operations,
> the cpu may change in between the rmw's read and write: they should
> be using this_cpu operations (or, I put preempt_disable/enable in the
> __rcu_read_unlock below). __this_cpus there work out fine on x86,
> which was given good instructions to use; but not so well on PowerPC.
>
> I've been running successfully for an hour now with the patch below;
> but I expect you'll want to consider the tradeoffs, and may choose a
> different solution.
Didn't Linus recently rant about these __this_cpu vs this_cpu nonsense ?
I thought that was going out..
Cheers,
Ben.
next prev parent reply other threads:[~2012-05-02 21:22 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-30 22:37 linux-next ppc64: RCU mods cause __might_sleep BUGs Hugh Dickins
2012-04-30 23:14 ` Paul E. McKenney
2012-05-01 0:33 ` Benjamin Herrenschmidt
2012-05-01 5:10 ` Hugh Dickins
2012-05-01 14:22 ` Paul E. McKenney
2012-05-01 21:42 ` Hugh Dickins
2012-05-01 23:25 ` Paul E. McKenney
2012-05-02 20:25 ` Hugh Dickins
2012-05-02 20:49 ` Paul E. McKenney
2012-05-02 21:32 ` Paul E. McKenney
2012-05-02 21:36 ` Paul E. McKenney
2012-05-02 21:20 ` Benjamin Herrenschmidt [this message]
2012-05-02 21:54 ` Paul E. McKenney
2012-05-02 22:54 ` Hugh Dickins
2012-05-03 0:14 ` Paul E. McKenney
2012-05-03 0:24 ` Hugh Dickins
2012-05-07 16:21 ` Hugh Dickins
2012-05-07 18:50 ` Paul E. McKenney
2012-05-07 21:38 ` Hugh Dickins
2012-05-01 13:39 ` Paul E. McKenney
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