mm: numa: avoid unnecessary TLB flushes when setting NUMA hinting entries
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@suse.de>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Jones <davej@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 8e07342..fc00c8c 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1493,12 +1493,14 @@
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 dd599fc..4472781 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -86,6 +86,10 @@
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);