Re: [tip:sched/locking] sched: Add p->pi_lock to task_rq_lock()

[Arne Jansen]

On 03.06.2011 11:15, Peter Zijlstra wrote:
> On Thu, 2011-06-02 at 06:09 +0900, Linus Torvalds wrote:
>> Boot-time hang - maybe due to the mis-merge that re-introduced the
>> infinite media change signals for ide-cd?
>>
>> I just pushed out a fix, it may not have mirrored out yet.
>>
>> I dunno. Worth checking out before spending a lot of time bisecting.
> 
> Right, so that wasn't it. I haven't done a full bisect yet because I
> noticed it died on a usb suspend line every single time and that machine
> only had a single usb device, a memory stick, in it. So I simply pulled
> the stick and voila it booted. So something is screwy with usb suspend
> or something.
> 
> This of course means that I'm now completely unable to reproduce the
> issue at hand :/
> 
> Maybe if I try another box..
> 
> Anyway, Arne, how long did you wait before power cycling the box? The
> NMI watchdog should trigger in about a minute or so if it will trigger
> at all (its enabled in your config).

No, it doesn't trigger, but the hang is not as complete as I first
thought. A running iostat via ssh continues to give output for a while,
the serial console still reacts to return and prompts for login. But
after a while more and more locks up. The console locks as soon as I
sysrq-t.
Maybe it has also something to do with the place where I added the
printks (btrfs_scan_one_device). Also the 10k-print gets triggered
several times (though I only see 10 lines of output). Maybe you can
send me your test-module and I'll try that, so we have more equal
conditions.
What also might help: the maschine I'm testing with is a quad-core
X3450 with 8GB RAM.
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