lkml.org 
[lkml]   [2014]   [Nov]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: frequent lockups in 3.18rc4
On 11/26/2014 07:21 AM, Linus Torvalds wrote:
> On Tue, Nov 25, 2014 at 9:52 PM, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
>>
>> And leave it running for a while, and see if the trace is always the
>> same, or if there are variations on it...
>
> Amusing.
>
> Lookie here:
>
> http://lists.xenproject.org/archives/html/xen-changelog/2005-08/msg00310.html
>
> That's from 2005.

:-)

>
> Anyway, I don't see why the cr3 issue matters, *unless* there is some
> situation where the scheduler can run with interrupts enabled. And why
> this is Xen-related, I have no idea.
>
> The Xen patches seem to have lost that
>
> /* On Xen the line below does not always work. Needs investigating! */
>
> line when backporting the 2.6.29 patches to Xen. And clearly nobody
> investigated.
>
> So please do get me back-traces, and we'll investigate. Better late
> than never. But it does sound Xen-specific - although it's possible
> that Xen just triggers some timing (and has apparently been able to
> trigger it since 2005) that DaveJ now triggers on his one machine.

Yeah, this sounds plausible.

I'm working on the back traces right now, hope to have them soon.


Juergen

>
> So DaveJ, even though this does appear Xen-centric (Xentric?) and
> you're running on bare hardware, maybe you could do the same thing in
> that x86-64 vmalloc_fault(). The timing with Jürgen is kind of
> intriguing - if 3.18-rc made it happen much more often for him, maybe
> it really is very timing-sensitive, and you actually are seeing a
> non-Xen version of the same thing...
>
> Linus
>



\
 
 \ /
  Last update: 2014-11-26 08:21    [W:0.208 / U:0.152 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site