Hi! I've been trying to clean up soft-dirty bit usage. I can't cleanup
"ridiculous macros in pgtable-2level.h" completely because I need to
define _PAGE_FILE,_PAGE_PROTNONE,_PAGE_NUMA bits in sequence manner
like
#define _PAGE_BIT_FILE (_PAGE_BIT_PRESENT + 1) /* _PAGE_BIT_RW */
#define _PAGE_BIT_NUMA (_PAGE_BIT_PRESENT + 2) /* _PAGE_BIT_USER */
#define _PAGE_BIT_PROTNONE (_PAGE_BIT_PRESENT + 3) /* _PAGE_BIT_PWT */
which can't be done right now because numa code needs to save original
pte bits for example in __split_huge_page_map, if I'm not missing something
obvious.
Also if we ever redefine the bits above we will need to update PAT code
which uses _PAGE_GLOBAL + _PAGE_PRESENT to make pte_present return true
or false.
Another weird thing I found is the following sequence:
mprotect_fixup
change_protection (passes @prot_numa = 0 which finally ends up in)
...
change_pte_range(..., prot_numa)
if (!prot_numa) {
...
} else {
... this seems to be dead code branch ...
}
is it intentional, and @prot_numa argument is supposed to be passed
with prot_numa = 1 one day, or it's leftover from old times?
Note I've not yet tested the series building it now, hopefully finish
testing in a couple of hours.
Linus, by saying "define the bits we use when PAGE_PRESENT==0 separately
and explicitly" you meant complete rework of the bits, right? Not simply
group them in once place in a header?
Cyrill
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