Re: Hang on large copy_from_user with PREEMPT_NONE

From: Michal Hocko
Date: Tue Apr 07 2015 - 10:30:22 EST


On Tue 07-04-15 13:05:31, Ingo Molnar wrote:
>
> * Borislav Petkov <bp@xxxxxxxxx> wrote:
>
> > On Tue, Apr 07, 2015 at 11:31:45AM +0200, Ingo Molnar wrote:
> > > Would be nice to see the actual kernel .config, as there's a few
> > > debug features that can slow things down significantly, such as
> > > CONFIG_KMEMCHECK=y or in some cases CONFIG_DEBUG_PAGEALLOC=y.
> >
> > He sent it here: https://lkml.kernel.org/r/55229D7E.6080309@xxxxxxxxxx
> >
> > I'm attaching it again.
>
> Thanks. Nothing particularly expensive stands out to me at a quick
> glance:-/

Sasha uses KASAN very often and it is enabled here as well. I guess this
might slow things really down.
--
Michal Hocko
SUSE Labs
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