> The final version of this fix will likely depend on some machinery/code
> introduced by 3ccfebedd8cf54 ("powerpc, membarrier: Skip memory barrier
> in switch_mm()"); but, yes, nothing we can't safely adjust I think.
Ya, I guess we'll have to look to know for sure but hopefully it's
manageable.
Absolutely. One approach would be to follow what PowerPC did: AFAIU, before
3ccfebedd8cf54 membarrier/powerpc used to hard code the required barrier in
in finish_task_switch(), "masking" it as an smp_mb__after_unlock_lock(); riscv
could use a similar approach (though with a different/new mask function).
Alternatively, we could maybe keep the barrier in switch_mm().
But let me complete and send out v2 with the fix at stake... this should give
us a more concrete basis to discuss about these matters.
Andrea