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kernel: mmu: move when page fault is counted

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The beginning of code in do_page_fault() is to pin the page
in memory if it is already present in physical memory.
It is there so that if a page is not present, it can proceed
to perform page-in and then pin it. So the counting of
page faults needs to be moved after the pinning code so
it actually counts page faults, and not counting pinning
operations when the page is already present.

Also clarify the comment on the goto statement as it is not
correct.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
This commit is contained in:
Daniel Leung 2021-07-13 14:08:05 -07:00 committed by Christopher Friedt
parent ebbfde9742
commit 7771d27525
1 changed files with 8 additions and 3 deletions
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11
kernel/mmu.c
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@ -1239,8 +1239,6 @@ static bool do_page_fault(void *addr, bool pin)
}
result = true;
paging_stats_faults_inc(faulting_thread, key);
if (status == ARCH_PAGE_LOCATION_PAGED_IN) {
if (pin) {
/* It's a physical memory address */
@ -1249,12 +1247,19 @@ static bool do_page_fault(void *addr, bool pin)
pf = z_phys_to_page_frame(phys);
pf->flags |= Z_PAGE_FRAME_PINNED;
}
/* We raced before locking IRQs, re-try */
/* This if-block is to pin the page if it is
* already present in physical memory. There is
* no need to go through the following code to
* pull in the data pages. So skip to the end.
*/
goto out;
}
__ASSERT(status == ARCH_PAGE_LOCATION_PAGED_OUT,
"unexpected status value %d", status);
paging_stats_faults_inc(faulting_thread, key);
pf = free_page_frame_list_get();
if (pf == NULL) {
/* Need to evict a page frame */