Re: [RFC PATCH v3 12/24] x86/mm: Modify ptep_set_wrprotect and pmdp_set_wrprotect for _PAGE_DIRTY_SW
- From
- Dave Hansen <dave.hansen@linux.intel.com>
- Date
- 2018-08-31 14:49:55
- Also in
- linux-arch, linux-doc, linux-mm, lkml
- Reply to
- Yu-cheng Yu, 2018-08-31
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.