On 08/31/2018 07:33 AM, Yu-cheng Yu wrote:
> Please use the form:
>
> pte_t new_pte, pte = READ_ONCE(*ptep);
> do {
> new_pte = /* ... */;
> } while (!try_cmpxchg(ptep, &pte, new_pte);
It's probably also worth doing some testing to see if you can detect the
cost of the cmpxchg. It's definitely more than the old code.
A loop that does mprotect(PROT_READ) followed by
mprotect(PROT_READ|PROT_WRITE) should do it.
