On Thu, Aug 07, 2014 at 10:58:41AM -0700, Dave Hansen wrote:
>
> From: Dave Hansen <dave.han...@linux.intel.com>
>
> This is a bug fix that needs to be pushed to mainline before the
> 3.17 release.
>
> Dave Jones reported seeing a bug from one of my TLB tracepoints:
>
> http://lkml.kernel.org/r/20140806181801.ga4...@redhat.com
>
> According to Paul McKenney, the right way to fix this is adding
> an _rcuidle suffix to the tracepoint.
>
> http://lkml.kernel.org/r/20140807065055.ga5...@linux.vnet.ibm.com
>
> This patch does just that.
>
> Signed-off-by: Dave Hansen <dave.han...@linux.intel.com>
> Reported-by: Dave Jones <da...@redhat.com>,
> Cc: paul...@linux.vnet.ibm.com
Reviewed-by: Paul E. McKenney <paul...@linux.vnet.ibm.com>
> ---
>
> b/arch/x86/mm/tlb.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff -puN arch/x86/mm/tlb.c~mm-fix-rcu-splat-from-tlb-tracepoints
> arch/x86/mm/tlb.c
> --- a/arch/x86/mm/tlb.c~mm-fix-rcu-splat-from-tlb-tracepoints 2014-08-07
> 10:55:43.312283542 -0700
> +++ b/arch/x86/mm/tlb.c 2014-08-07 10:56:49.763352575 -0700
> @@ -49,7 +49,13 @@ void leave_mm(int cpu)
> if (cpumask_test_cpu(cpu, mm_cpumask(active_mm))) {
> cpumask_clear_cpu(cpu, mm_cpumask(active_mm));
> load_cr3(swapper_pg_dir);
> - trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
> + /*
> + * This gets called in the idle path where RCU
> + * functions differently. Tracing normally
> + * uses RCU, so we have to call the tracepoint
> + * specially here.
> + */
> + trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH,
> TLB_FLUSH_ALL);
> }
> }
> EXPORT_SYMBOL_GPL(leave_mm);
> _
>
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