From: Dave Jones <davej@redhat.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Oleg Nesterov <oleg@redhat.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Serge Hallyn <serge.hallyn@canonical.com>,
linux-kernel@vger.kernel.org
Subject: Re: lots of suspicious RCU traces
Date: Fri, 26 Oct 2012 11:16:36 -0400 [thread overview]
Message-ID: <20121026151636.GA1578@redhat.com> (raw)
In-Reply-To: <CAFTL4hw=orRVYzuk8L1aBHCxVD05uT_fdFoRJ_BkihoNd0huJg@mail.gmail.com>
On Fri, Oct 26, 2012 at 11:44:11AM +0200, Frederic Weisbecker wrote:
> 2012/10/25 Sergey Senozhatsky <sergey.senozhatsky@gmail.com>:
> > On (10/25/12 09:06), Frederic Weisbecker wrote:
> >> >> > My understanding is (I may be wrong) that we can schedule() from ptrace chain to
> >> >> > some arbitrary task, which will continue its execution from the point where RCU assumes
> >> >> > CPU as not idle, while CPU in fact still in idle state -- no one said rcu_idle_exit()
> >> >> > (or similar) prior to schedule() call.
> >> >>
> >> >> Yeah but when we are in syscall_trace_leave(), the CPU shouldn't be in
> >> >> RCU idle mode. That's where the bug is. How do you manage to trigger
> >> >> this bug?
> >> >
> >> > strace -f <anything>
> >> I can't reproduce. Can you send me your config?
> >
> > sure, attached.
>
> Thanks.
>
> Sergey, Dave,
>
> Does the patch I just sent you fix the issue?
I only saw this happening after hours of fuzzing.
Right now I keep running into other issues before that gets a chance to happen,
so I've not seen it in a while.
I'll apply it to my tree, and run with it though.
If I see it again, you'll be first to know :)
Dave
next prev parent reply other threads:[~2012-10-26 15:17 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-17 3:49 lots of suspicious RCU traces Dave Jones
2012-10-24 16:42 ` Sergey Senozhatsky
2012-10-24 18:06 ` Oleg Nesterov
2012-10-24 18:21 ` Sergey Senozhatsky
2012-10-24 18:52 ` Oleg Nesterov
2012-10-24 19:17 ` Sergey Senozhatsky
2012-10-24 19:41 ` Paul E. McKenney
2012-10-24 19:50 ` Sergey Senozhatsky
2012-10-24 20:11 ` Paul E. McKenney
2012-10-24 20:15 ` Sergey Senozhatsky
2012-10-24 22:32 ` Frederic Weisbecker
2012-10-25 5:50 ` Sergey Senozhatsky
2012-10-25 7:06 ` Frederic Weisbecker
2012-10-25 7:41 ` Sergey Senozhatsky
2012-10-26 9:40 ` [PATCH] rcu: Fix unrecovered RCU user mode in syscall_trace_leave() Frederic Weisbecker
2012-10-26 9:44 ` lots of suspicious RCU traces Frederic Weisbecker
2012-10-26 11:16 ` Sergey Senozhatsky
2012-10-26 15:16 ` Dave Jones [this message]
2012-10-25 5:55 ` Sergey Senozhatsky
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