From: Mel Gorman <mgorman@xxxxxxx>
Subject: mm: clear pmd_numa before invalidating
On x86, PMD entries are similar to _PAGE_PROTNONE protection and are
handled as NUMA hinting faults. The following two page table protection
bits are what defines them
_PAGE_NUMA:set _PAGE_PRESENT:clear
A PMD is considered present if any of the _PAGE_PRESENT, _PAGE_PROTNONE,
_PAGE_PSE or _PAGE_NUMA bits are set. If pmdp_invalidate encounters a
pmd_numa, it clears the present bit leaving _PAGE_NUMA which will be
considered not present by the CPU but present by pmd_present. The
existing caller of pmdp_invalidate should handle it but it's an
inconsistent state for a PMD. This patch keeps the state consistent when
calling pmdp_invalidate.
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Alex Thorlton <athorlton@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/pgtable-generic.c | 3 +++
1 file changed, 3 insertions(+)
diff -puN mm/pgtable-generic.c~mm-clear-pmd_numa-before-invalidating mm/pgtable-generic.c
--- a/mm/pgtable-generic.c~mm-clear-pmd_numa-before-invalidating
+++ a/mm/pgtable-generic.c
@@ -191,6 +191,9 @@ pgtable_t pgtable_trans_huge_withdraw(st
void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp)
{
+ pmd_t entry = *pmdp;
+ if (pmd_numa(entry))
+ entry = pmd_mknonnuma(entry);
set_pmd_at(vma->vm_mm, address, pmdp, pmd_mknotpresent(*pmdp));
flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
}
_
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