Re: [PATCH] context_tracking: Restore previous state in schedule_user

Dave Jones
2014-12-04T00:30:39Z

On Wed, Dec 03, 2014 at 04:04:31PM -0800, Andy Lutomirski wrote:
> On Wed, Dec 3, 2014 at 3:58 PM, Frederic Weisbecker <fweisbec@gmail.com> wrote:
> > On Wed, Dec 03, 2014 at 03:18:41PM -0800, Andy Lutomirski wrote:
> >> It appears that some SCHEDULE_USER (asm for schedule_user) callers
> >> in arch/x86/kernel/entry_64.S are called from RCU kernel context,
> >> and schedule_user will return in RCU user context. This causes RCU
> >> warnings and possible failures.
> >>
> >> This is intended to be a minimal fix suitable for 3.18.
> >>
> >> Reported-by: Dave Jones <davej@redhat.com>
> >> Cc: Oleg Nesterov <oleg@redhat.com>
> >> Cc: Frédéric Weisbecker <fweisbec@gmail.com>
> >> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
> >> Signed-off-by: Andy Lutomirski <luto@amacapital.net>
> >
> > Ah, we sent it about at the same time :-)
> >
> > Might be too late for 3.18 though because it's not a regression.

Wait, so how come that trace didn't start showing up until recently ?

Dave