From: john.stultz@linaro.org (John Stultz)
To: linux-arm-kernel@lists.infradead.org
Subject: v3.13-rc6+ regression (ARM board)
Date: Thu, 02 Jan 2014 12:30:12 -0800 [thread overview]
Message-ID: <52C5CC54.4050602@linaro.org> (raw)
In-Reply-To: <52C5C5F6.70803@linaro.org>
On 01/02/2014 12:03 PM, John Stultz wrote:
> On 01/02/2014 11:38 AM, Linus Torvalds wrote:
>> On Thu, Jan 2, 2014 at 4:07 AM, Krzysztof Ha?asa <khalasa@piap.pl> wrote:
>>> This means these two commits don't like each other:
>>>
>>> seqcount: Add lockdep functionality to seqcount/seqlock structures
>>> sched_clock: Use seqcount instead of rolling our own
>> Does something like this fix it for you?
>>
>> --- a/kernel/time/sched_clock.c
>> +++ b/kernel/time/sched_clock.c
>> @@ -36,6 +36,7 @@ core_param(irqtime, irqtime, int, 0400);
>>
>> static struct clock_data cd = {
>> .mult = NSEC_PER_SEC / HZ,
>> + .seq = SEQCNT_ZERO(cd.seq),
>> };
>>
>> static u64 __read_mostly sched_clock_mask;
>>
>> (The above is not even compile-tested, because x86 doesn't use
>> GENERIC_SCHED_CLOCK. So I did the patch blindly, but I think you get
>> the idea..)
> Sheesh. Just finishing up holiday email backlog and Linus already has a
> fix. :)
>
> This looks like it should fix the issue, and does build for me.
>
> Assuming it works for Krzysztof,
So something else may be at play. Even with Linus' patch I reproduced a
similar hang here.
Still chasing it down, but it looks like a seqlock deadlock where we're
calling read while holding the lock.
thanks
-john
next prev parent reply other threads:[~2014-01-02 20:30 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-31 10:37 v3.13-rc6+ regression (ARM board) Krzysztof Hałasa
2013-12-31 10:45 ` Willy Tarreau
2014-01-02 10:02 ` Krzysztof Hałasa
2014-01-02 10:14 ` Uwe Kleine-König
2014-01-02 12:07 ` Krzysztof Hałasa
2014-01-02 19:38 ` Linus Torvalds
2014-01-02 20:03 ` John Stultz
2014-01-02 20:30 ` John Stultz [this message]
2014-01-02 20:42 ` Stephen Boyd
2014-01-02 20:52 ` John Stultz
2014-01-02 20:43 ` Linus Torvalds
2014-01-02 21:34 ` John Stultz
2014-01-02 21:54 ` [PATCH] sched_clock: Disable seqlock lockdep usage in sched_clock John Stultz
2014-01-02 22:15 ` Linus Torvalds
2014-01-02 22:21 ` John Stultz
2014-01-02 23:11 ` [PATCH 1/2] seqlock: Use raw_ prefix instead of _no_lockdep John Stultz
2014-01-02 23:11 ` [PATCH 2/2] sched_clock: Disable seqlock lockdep usage in sched_clock John Stultz
2014-01-03 0:46 ` Stephen Boyd
2014-01-03 6:05 ` Krzysztof Hałasa
2014-01-03 0:46 ` [PATCH 1/2] seqlock: Use raw_ prefix instead of _no_lockdep Stephen Boyd
2014-01-03 0:50 ` Linus Torvalds
2014-01-04 0:28 ` John Stultz
2014-01-06 10:10 ` Peter Zijlstra
2014-01-03 6:01 ` v3.13-rc6+ regression (ARM board) Krzysztof Hałasa
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