From: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Viresh Kumar <viresh.kumar@linaro.org>
Subject: Re: Regression on cpufreq in v3.12-rc1
Date: Thu, 19 Sep 2013 18:28:54 +0530 [thread overview]
Message-ID: <523AF50E.1040502@linux.vnet.ibm.com> (raw)
In-Reply-To: <CACRpkdYxiDA25Yb+csWWgXMmJuKMMTNVbdF+2JUnsSrXQpYysQ@mail.gmail.com>
On 09/19/2013 06:25 PM, Linus Walleij wrote:
> On Thu, Sep 19, 2013 at 2:46 PM, Srivatsa S. Bhat
> <srivatsa.bhat@linux.vnet.ibm.com> wrote:
>
>>>> I don't really know if this is the right solution at all, so please
>>>> help me out here... if you want that patch I can send it once
>>>> I understand this properly.
>>
>> IIRC, recent kernels didn't return 0 or any error code when the !policy
>> condition was matched. So can you check whether this problem occurs with
>> 3.11 or 3.10 as well?
>
> v3.11 works fine.
>
> The problem is not what it returns, the system seems to survive no matter
> whether it returns 0 or 17 or whatever.
>
Of course. What I intended to say was that I don't recall recent kernels
returning _anything_ on !policy. So there wasn't any sudden change in _that_
piece of code, AFAIR.
> The problem is that sometimes in the v3.12 kernel cycle we got a
> BUG() crash instead of some random value back for calling early.
>
Yep, and that's most likely due to some change in ordering of calls somewhere,
which makes calls to lock_policy_rwsem_read() before it is safe to do so,
rather than anything related to how lock_policy_rwsem_read() handles the call.
>> So I think we should first identify (bisect?) and understand what caused that
>> particular change and then we will be in a position to evaluate whether the
>> patch you proposed would be the right fix or not.
>
> I'll see if I can get a bisect going, the problem is that I upload the
> kernel over the serial port so this isn't a very quick procedure :-(
>
Hmmm.. :-/
Regards,
Srivatsa S. Bhat
next prev parent reply other threads:[~2013-09-19 13:17 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-18 21:21 Regression on cpufreq in v3.12-rc1 Linus Walleij
2013-09-18 22:41 ` Rafael J. Wysocki
2013-09-19 12:21 ` Linus Walleij
2013-09-19 12:46 ` Srivatsa S. Bhat
2013-09-19 12:55 ` Linus Walleij
2013-09-19 12:58 ` Srivatsa S. Bhat [this message]
2013-09-19 14:12 ` Viresh Kumar
2013-09-19 18:11 ` Srivatsa S. Bhat
2013-09-19 18:17 ` Srivatsa S. Bhat
2013-09-20 4:19 ` Viresh Kumar
2013-09-20 10:13 ` Srivatsa S. Bhat
2013-09-20 8:43 ` Linus Walleij
2013-09-20 8:33 ` Linus Walleij
2013-09-20 8:39 ` Viresh Kumar
2013-09-20 8:41 ` Linus Walleij
2013-09-20 8:49 ` Viresh Kumar
2013-09-20 9:35 ` Viresh Kumar
2013-09-20 15:16 ` Srivatsa S. Bhat
2013-09-20 16:54 ` Viresh Kumar
2013-09-21 5:47 ` Srivatsa S. Bhat
2013-09-20 15:36 ` Linus Walleij
2013-09-20 15:39 ` Linus Walleij
2013-09-20 17:05 ` Viresh Kumar
2013-09-20 17:31 ` Linus Walleij
2013-09-20 15:21 ` Linus Walleij
2013-09-20 15:32 ` Srivatsa S. Bhat
2013-09-20 15:40 ` Linus Walleij
2013-09-20 16:34 ` Linus Walleij
2013-09-20 17:01 ` Viresh Kumar
2013-09-21 5:48 ` Srivatsa S. Bhat
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