If a PTE or PMD is already marked NUMA when scanning to mark entries
for NUMA hinting then it is not necessary to update the entry and
incur a TLB flush penalty. Avoid the avoidhead where possible.
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
---
mm/huge_memory.c | 14 ++++++++------
mm/mprotect.c | 4 ++++
2 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 8546654..f2bf521 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1524,12 +1524,14 @@ int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
return 0;
}
- ret = 1;
- entry = pmdp_get_and_clear_notify(mm, addr, pmd);
- entry = pmd_modify(entry, newprot);
- ret = HPAGE_PMD_NR;
- set_pmd_at(mm, addr, pmd, entry);
- BUG_ON(pmd_write(entry));
+ if (!prot_numa || !pmd_protnone(*pmd)) {
+ ret = 1;
+ entry = pmdp_get_and_clear_notify(mm, addr, pmd);
+ entry = pmd_modify(entry, newprot);
+ ret = HPAGE_PMD_NR;
+ set_pmd_at(mm, addr, pmd, entry);
+ BUG_ON(pmd_write(entry));
+ }
spin_unlock(ptl);
}
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 33dfafb..109e7aa 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -86,6 +86,10 @@ static unsigned long change_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
page = vm_normal_page(vma, addr, oldpte);
if (!page || PageKsm(page))
continue;
+
+ /* Avoid TLB flush if possible */
+ if (pte_protnone(oldpte))
+ continue;
}
ptent = ptep_modify_prot_start(mm, addr, pte);
--
2.1.2
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