[PATCH]x86: make spurious_fault check correct pte bit

From: Shaohua Li
Date: Tue Jul 27 2010 - 04:06:38 EST

pte_present() returns true even present bit isn't set but _PAGE_PROTNONE
(global bit) bit is set. While with CONFIG_DEBUG_PAGEALLOC, free pages have
global bit set but present bit clear. This patch makes we could catch
free pages access with CONFIG_DEBUG_PAGEALLOC enabled.

Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index f627779..93afd78 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -893,7 +893,7 @@ spurious_fault(unsigned long error_code, unsigned long address)
return spurious_fault_check(error_code, (pte_t *) pmd);

pte = pte_offset_kernel(pmd, address);
- if (!pte_present(*pte))
+ if (!(pte_flags(*pte) & _PAGE_PRESENT))
return 0;

ret = spurious_fault_check(error_code, pte);

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