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Subject[RFC][PATCH v2 13/21] x86/pgtable: dont check PMD accessed bit
From: Jingqi Liu <jingqi.liu@intel.com>

ept-idle will clear PMD accessed bit to speedup PTE scan -- if the bit
remains unset in the next scan, all the 512 PTEs can be skipped.

So don't complain on !_PAGE_ACCESSED in pmd_bad().

Note that clearing PMD accessed bit has its own cost, the optimization
may only be worthwhile for
- large idle area
- sparsely populated area

Signed-off-by: Jingqi Liu <jingqi.liu@intel.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
---
arch/x86/include/asm/pgtable.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- linux.orig/arch/x86/include/asm/pgtable.h 2018-12-23 19:50:50.917902600 +0800
+++ linux/arch/x86/include/asm/pgtable.h 2018-12-23 19:50:50.913902605 +0800
@@ -821,7 +821,8 @@ static inline pte_t *pte_offset_kernel(p

static inline int pmd_bad(pmd_t pmd)
{
- return (pmd_flags(pmd) & ~_PAGE_USER) != _KERNPG_TABLE;
+ return (pmd_flags(pmd) & ~(_PAGE_USER | _PAGE_ACCESSED)) !=
+ (_KERNPG_TABLE & ~_PAGE_ACCESSED);
}

static inline unsigned long pages_to_mb(unsigned long npg)

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