Re: frequent lockups in 3.18rc4

From: Dave Jones
Date: Wed Nov 19 2014 - 17:20:11 EST

On Wed, Nov 19, 2014 at 11:38:09AM -0800, Linus Torvalds wrote:

> > Is it possible that we've managed to return to userspace with
> > interrupts off somehow? A loop in userspace that somehow has
> > interrupts off can cause all kinds of fun lockups.
> That sounds unlikely, but if there is some stack corruption going on.
> However, it wouldn't even explain things, because even if interrupts
> had been disabled in user space, and even if that popf got executed,
> this wouldn't be where they got enabled. That would be the :"sti" in
> the system call entry path (hidden behind the ENABLE_INTERRUPTS
> macro).
> Of course, maybe Dave has paravirtualization enabled (what a crock
> _that_ is), and there is something wrong with that whole code.

I've had HYPERVISOR_GUEST disabled for a while, which also disables
the paravirt code afaics.


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