Re: [RFC PATCH 1/3] sched: fix exit_mm vs membarrier (v3)

2020-10-07 Thread Peter Zijlstra
On Wed, Oct 07, 2020 at 10:57:52AM -0400, Mathieu Desnoyers wrote: > - On Oct 7, 2020, at 10:29 AM, Peter Zijlstra pet...@infradead.org wrote: > > > On Thu, Sep 24, 2020 at 01:25:06PM -0400, Mathieu Desnoyers wrote: > >> diff --git a/kernel/exit.c b/kernel/exit.c > >> index 733e80f334e7..0767a

Re: [RFC PATCH 1/3] sched: fix exit_mm vs membarrier (v3)

2020-10-07 Thread Mathieu Desnoyers
- On Oct 7, 2020, at 10:29 AM, Peter Zijlstra pet...@infradead.org wrote: > On Thu, Sep 24, 2020 at 01:25:06PM -0400, Mathieu Desnoyers wrote: >> diff --git a/kernel/exit.c b/kernel/exit.c >> index 733e80f334e7..0767a2dbf245 100644 >> --- a/kernel/exit.c >> +++ b/kernel/exit.c >> @@ -475,7 +47

Re: [RFC PATCH 1/3] sched: fix exit_mm vs membarrier (v3)

2020-10-07 Thread Peter Zijlstra
On Thu, Sep 24, 2020 at 01:25:06PM -0400, Mathieu Desnoyers wrote: > diff --git a/kernel/exit.c b/kernel/exit.c > index 733e80f334e7..0767a2dbf245 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -475,7 +475,19 @@ static void exit_mm(void) > BUG_ON(mm != current->active_mm); > /*

[RFC PATCH 1/3] sched: fix exit_mm vs membarrier (v3)

2020-09-24 Thread Mathieu Desnoyers
exit_mm should issue memory barriers after user-space memory accesses, before clearing current->mm, to order user-space memory accesses performed prior to exit_mm before clearing tsk->mm, which has the effect of skipping the membarrier private expedited IPIs. exit_mm should also update the runqueu