Re: [PATCH] perf, x86: Fall back to vmalloc for BTS buffer allocation

From: Peter Zijlstra
Date: Wed Sep 10 2014 - 12:36:13 EST


On Wed, Sep 10, 2014 at 04:40:12PM +0200, Andi Kleen wrote:
> > We did this once, and that blew up big time.
> >
> > Even now, vmalloc_fault() has a very explicit:
> >
> > WARN_ON_ONCE(in_nmi());
> >
> > So this isn't going to happen until you fix that.
>
> Good point.
>
> We just need to call vmalloc_sync_all at allocation time,
> no need to change vmalloc_fault.

Somehow that wasn't considered adequate, but lemme try and dig out that
thread. It should be somewhere...

https://lkml.org/lkml/2010/7/14/465


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