Re: frequent lockups in 3.18rc4

From: Andy Lutomirski
Date: Thu Nov 20 2014 - 18:55:39 EST

On Thu, Nov 20, 2014 at 3:39 PM, Tejun Heo <tj@xxxxxxxxxx> wrote:
> On Thu, Nov 20, 2014 at 03:08:03PM -0800, Andy Lutomirski wrote:
>> > So, for now, all we need is adding nmi check in percpu accessors,
>> > right?
>> >
>> What's the issue with nmi? Page faults are supposed to nest correctly
>> inside nmi, right?
> Thought they couldn't. Looking at the trace that Frederic linked, it
> looks like straight-out tracing function recursion due to an
> unexpected fault while holding a lock. I don't think this can be
> annotated from percpu accessor side. There's nothing special about
> the context. :(

That doesn't appear to have anything to with nmi though, right?

Wouldn't this issue be fixed by moving the vmalloc_fault check into
do_page_fault before exception_enter?

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