Re: [RFC PATCH] sched: Add missing memory barrier in switch_mm_cid

From: Yeo Reum Yun
Date: Mon Mar 11 2024 - 04:45:28 EST


Hi. Mathieu. Sorry to late answer.

> diff --git a/arch/x86/include/asm/barrier.h b/arch/x86/include/asm/barrier.h
> index 35389b2af88e..0d5e54201eb2 100644
> --- a/arch/x86/include/asm/barrier.h
> +++ b/arch/x86/include/asm/barrier.h
> @@ -79,6 +79,9 @@ do { \
> #define __smp_mb__before_atomic() do { } while (0)
> #define __smp_mb__after_atomic() do { } while (0)

> +/* Writing to CR3 provides a full memory barrier in switch_mm(). */
> +#define smp_mb__after_switch_mm() do { } while (0)
> +
> #include <asm-generic/barrier.h>

IIUC, ppc already does smp_mb() in switch_mm.

Would it better to add the same macro which do nothing to pcc?\\

Thanks!

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