On Mon, Jun 15, 2015 at 04:38:21PM -0300, Rafael David Tinoco wrote:
> Any thoughts ?
This recently came up again and I proposed the below. Reposting because
the original had a silly compile fail.
---
Subject: stop_machine: Fix deadlock between multiple stop_two_cpus()
From: Peter Zijlstra
Date:
Peter, Sasha, coming back to this…
Not that this is happening frequently or I can easily reproduce, but…
> On May14, 2014, at 07:26 AM, Peter Zijlstra wrote:
>
> On Wed, May 14, 2014 at 02:21:04PM +0400, Kirill Tkhai wrote:
>>
>>
>> 14.05.2014, 14:14, "Peter Zijlstra" :
>>> On Wed, May 14, 20
On Wed, May 14, 2014 at 12:26:02PM +0200, Peter Zijlstra wrote:
> so we serialize stop_cpus_work() vs stop_two_cpus() with an l/g lock.
>
> Ah, but stop_cpus_work() only holds the global lock over queueing, it
> doesn't wait for completion, that might indeed cause a problem.
Hmm, is this so? If
On Wed, May 14, 2014 at 02:21:04PM +0400, Kirill Tkhai wrote:
>
>
> 14.05.2014, 14:14, "Peter Zijlstra" :
> > On Wed, May 14, 2014 at 01:42:32PM +0400, Kirill Tkhai wrote:
> >
> >> Peter, do we have to queue stop works orderly?
> >>
> >> Is there is not a possibility, when two pair of works que
14.05.2014, 14:14, "Peter Zijlstra" :
> On Wed, May 14, 2014 at 01:42:32PM +0400, Kirill Tkhai wrote:
>
>> Peter, do we have to queue stop works orderly?
>>
>> Is there is not a possibility, when two pair of works queued different on
>> different cpus?
>>
>> kernel/stop_machine.c | 10 ++
On Wed, May 14, 2014 at 01:42:32PM +0400, Kirill Tkhai wrote:
> Peter, do we have to queue stop works orderly?
>
> Is there is not a possibility, when two pair of works queued different on
> different cpus?
>
>
> kernel/stop_machine.c | 10 --
> 1 file changed, 8 insertions(+), 2 deleti
12.05.2014, 22:49, "Sasha Levin" :
> On 04/11/2014 11:16 AM, Kirill Tkhai wrote:
>
>> 11.04.2014, 18:33, "Sasha Levin" :
On 04/10/2014 09:38 AM, Kirill Tkhai wrote:
>> 10.04.2014, 11:00, "Michael wang" :
>> On 04/10/2014 11:31 AM, Sasha Levin wrote:
>> [snip]
>>
On 04/11/2014 11:16 AM, Kirill Tkhai wrote:
> 11.04.2014, 18:33, "Sasha Levin" :
>> > On 04/10/2014 09:38 AM, Kirill Tkhai wrote:
>> >
>>> >> 10.04.2014, 11:00, "Michael wang" :
> On 04/10/2014 11:31 AM, Sasha Levin wrote:
> [snip]
>>> >> I'd like to re-open this issu
11.04.2014, 18:33, "Sasha Levin" :
> On 04/10/2014 09:38 AM, Kirill Tkhai wrote:
>
>> 10.04.2014, 11:00, "Michael wang" :
On 04/10/2014 11:31 AM, Sasha Levin wrote:
[snip]
>> I'd like to re-open this issue. It seems that something broke and I'm
>> now seeing the same issues
On 04/10/2014 09:38 AM, Kirill Tkhai wrote:
> 10.04.2014, 11:00, "Michael wang" :
>> > On 04/10/2014 11:31 AM, Sasha Levin wrote:
>> > [snip]
>> >
>>> >> I'd like to re-open this issue. It seems that something broke and I'm
>>> >> now seeing the same issues that have gone away 2 months with this
10.04.2014, 11:00, "Michael wang" :
> On 04/10/2014 11:31 AM, Sasha Levin wrote:
> [snip]
>
>> I'd like to re-open this issue. It seems that something broke and I'm
>> now seeing the same issues that have gone away 2 months with this patch
>> again.
>
> A new mechanism has been designed to move
On Wed, Apr 09, 2014 at 11:31:48PM -0400, Sasha Levin wrote:
> I'd like to re-open this issue. It seems that something broke and I'm
> now seeing the same issues that have gone away 2 months with this patch
> again.
Weird; we didn't touch anything in the last few weeks :-/
> Stack trace is simila
On 04/10/2014 11:31 AM, Sasha Levin wrote:
[snip]
>
> I'd like to re-open this issue. It seems that something broke and I'm
> now seeing the same issues that have gone away 2 months with this patch
> again.
A new mechanism has been designed to move the priority checking inside
idle_balance(), inc
On 02/24/2014 07:12 AM, Peter Zijlstra wrote:
> Subject: sched: Guarantee task priority in pick_next_task()
> From: Peter Zijlstra
> Date: Fri Feb 14 12:25:08 CET 2014
>
> Michael spotted that the idle_balance() push down created a task
> priority problem.
>
> Previously, when we called idle_bal
On 02/25/2014 06:49 PM, Peter Zijlstra wrote:
> On Tue, Feb 25, 2014 at 12:47:01PM +0800, Michael wang wrote:
>> On 02/24/2014 09:10 PM, Peter Zijlstra wrote:
>>> On Mon, Feb 24, 2014 at 01:12:18PM +0100, Peter Zijlstra wrote:
+ if (p) {
+ if (unlikely(p == RETRY
On Mon, Feb 24, 2014 at 01:21:48PM -0500, Sasha Levin wrote:
> Sign me up to the fan club of this patch, I love it.
I've converted that in a Tested-by: tag :-)
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On Tue, Feb 25, 2014 at 12:47:01PM +0800, Michael wang wrote:
> On 02/24/2014 09:10 PM, Peter Zijlstra wrote:
> > On Mon, Feb 24, 2014 at 01:12:18PM +0100, Peter Zijlstra wrote:
> >> + if (p) {
> >> + if (unlikely(p == RETRY_TASK))
> >> + goto agai
On 02/24/2014 09:10 PM, Peter Zijlstra wrote:
> On Mon, Feb 24, 2014 at 01:12:18PM +0100, Peter Zijlstra wrote:
>> +if (p) {
>> +if (unlikely(p == RETRY_TASK))
>> +goto again;
>
> We could even make that: unlikely(p & 1), I think most CPU
On 02/24/2014 08:12 PM, Peter Zijlstra wrote:
[snip]
>>
>> ...what about move idle_balance() back to it's old position?
>
> I've always hated that, idle_balance() is very much a fair policy thing
> and shouldn't live in the core code.
>
>> pull_rt_task() logical could be after idle_balance() if s
On 02/25/2014 02:21 AM, Sasha Levin wrote:
[snip]
>>
>> Fixes: 38033c37faab ("sched: Push down pre_schedule() and
>> idle_balance()")
>> Cc: Juri Lelli
>> Cc: Ingo Molnar
>> Cc: Steven Rostedt
>> Reported-by: Michael Wang
>> Signed-off-by: Peter Zijlstra
>
> Sign me up to the fan club of this patc
On 02/24/2014 07:12 AM, Peter Zijlstra wrote:
Anyway, the below seems to work; it avoids playing tricks with the idle
thread and instead uses a magic constant.
The comparison should be faster too; seeing how we avoid dereferencing
p->sched_class.
---
Subject: sched: Guarantee task priority in p
On Mon, Feb 24, 2014 at 01:12:18PM +0100, Peter Zijlstra wrote:
> + if (p) {
> + if (unlikely(p == RETRY_TASK))
> + goto again;
We could even make that: unlikely(p & 1), I think most CPUs can encode
that far better than the full pointer i
On Mon, Feb 24, 2014 at 06:14:24PM +0800, Michael wang wrote:
> On 02/24/2014 03:10 PM, Peter Zijlstra wrote:
> > On Mon, Feb 24, 2014 at 01:19:15PM +0800, Michael wang wrote:
> >> Peter, do we accidentally missed this commit?
> >>
> >> http://git.kernel.org/tip/477af336ba06ef4c32e97892bb0d2027ce30
On 02/24/2014 03:10 PM, Peter Zijlstra wrote:
> On Mon, Feb 24, 2014 at 01:19:15PM +0800, Michael wang wrote:
>> Peter, do we accidentally missed this commit?
>>
>> http://git.kernel.org/tip/477af336ba06ef4c32e97892bb0d2027ce30f466
>
> Ingo dropped it on Saturday because it makes locking_selftest(
On Mon, Feb 24, 2014 at 01:19:15PM +0800, Michael wang wrote:
> Peter, do we accidentally missed this commit?
>
> http://git.kernel.org/tip/477af336ba06ef4c32e97892bb0d2027ce30f466
Ingo dropped it on Saturday because it makes locking_selftest() unhappy.
That is because we call locking_selftest()
On 02/24/2014 12:19 AM, Michael wang wrote:
On 02/24/2014 11:23 AM, Sasha Levin wrote:
[snip]
>>>
>>>Could I get a link to the patch please? It's a pain testing other things
>>>with this issue reproducing every time.
>>
>>Please take a try on the latest tip tree, patches has been merged as I
>>
On 02/24/2014 11:23 AM, Sasha Levin wrote:
[snip]
>>>
>>> Could I get a link to the patch please? It's a pain testing other things
>>> with this issue reproducing every time.
>>
>> Please take a try on the latest tip tree, patches has been merged as I
>> saw :)
>
> Nope, still see it with latest -
On 02/21/2014 08:45 PM, Michael wang wrote:
On 02/22/2014 12:43 AM, Sasha Levin wrote:
On 02/19/2014 11:32 PM, Michael wang wrote:
On 02/20/2014 02:08 AM, Sasha Levin wrote:
Hi all,
While fuzzing with trinity inside a KVM tools guest, running latest
-next kernel, I see to hit the following ha
On 02/22/2014 12:43 AM, Sasha Levin wrote:
> On 02/19/2014 11:32 PM, Michael wang wrote:
>> On 02/20/2014 02:08 AM, Sasha Levin wrote:
>>> >Hi all,
>>> >
>>> >While fuzzing with trinity inside a KVM tools guest, running latest
>>> >-next kernel, I see to hit the following hang quite often.
>> Fix f
On 02/19/2014 11:32 PM, Michael wang wrote:
On 02/20/2014 02:08 AM, Sasha Levin wrote:
>Hi all,
>
>While fuzzing with trinity inside a KVM tools guest, running latest
>-next kernel, I see to hit the following hang quite often.
Fix for the stuck issue around idle_balance() is now in progress, th
On 02/20/2014 02:08 AM, Sasha Levin wrote:
> Hi all,
>
> While fuzzing with trinity inside a KVM tools guest, running latest
> -next kernel, I see to hit the following hang quite often.
Fix for the stuck issue around idle_balance() is now in progress, this
may caused be the same problem, I sugges
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