From: Andi Kleen <andi@firstfloor.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <andi@firstfloor.org>, Andi Kleen <ak@linux.intel.com>,
dave@sr71.net, linux-kernel@vger.kernel.org, mingo@kernel.org,
eranian@google.com, x86@kernel.org
Subject: Re: [PATCH 1/2] Use faster check for modules in backtrace on 64bit
Date: Tue, 30 Sep 2014 22:10:00 +0200 [thread overview]
Message-ID: <20140930200959.GB8196@two.firstfloor.org> (raw)
In-Reply-To: <20140930085814.GS5430@worktop>
> > Also I investigated it now, but we don't have RCU support for rbtrees.
> > So it would need some kind of locking for the reader, which is a show
> > stopper.
>
> Nah, we can trivially do that with a seqlock. Not read side locking
> required in the normal case.
I'm not convinced. It wouldn't surprise me if it was possible
to generate endless cycles with rcu freed memory on some rebalancing
operation. If you think I'm wrong please show working code.
Also please explain clearly for the module maintainers and me
what the problem with my original simple trivially show
to be correct solution is.
Thanks,
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2014-09-30 20:10 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-26 23:31 Optimize backtrace code for perf PMI handler Andi Kleen
2014-09-26 23:31 ` [PATCH 1/2] Use faster check for modules in backtrace on 64bit Andi Kleen
2014-09-29 11:42 ` Peter Zijlstra
2014-09-29 15:21 ` Andi Kleen
2014-09-29 20:30 ` Andi Kleen
2014-09-30 8:58 ` Peter Zijlstra
2014-09-30 20:10 ` Andi Kleen [this message]
2014-10-02 10:57 ` Peter Zijlstra
2014-10-03 23:20 ` Andi Kleen
2014-09-26 23:31 ` [PATCH 2/2] x86: Only do a single page fault for copy_from_user_nmi Andi Kleen
2014-09-29 11:56 ` Peter Zijlstra
2014-09-29 15:26 ` Andi Kleen
2014-10-03 4:53 ` Ingo Molnar
2014-10-03 23:25 ` Andi Kleen
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