[PATCH] Fix pageattr with mem=nopentium

This fixes a hang in change_page_attr() that occured with mem=nopentium.

Make sure a non large page kernel mapping is handled correctly.
Previously the page reference counter was handled incorrectly in this
case.

Also hardens change_page_attr against bogus addresses.  You get an
EINVAL now.

diff --git a/arch/i386/mm/pageattr.c b/arch/i386/mm/pageattr.c
index 536c29c3b9479e90f87c8d916fa03bc4c40cb951..b4e286cec50f91f6a133fc36e3b8eefb679774e1 100644 (file)
--- a/arch/i386/mm/pageattr.c
+++ b/arch/i386/mm/pageattr.c
@@ -16,7 +16,12 @@
 static inline pte_t *lookup_address(unsigned long address) 
 { 
        pgd_t *pgd = pgd_offset_k(address); 
-       pmd_t *pmd = pmd_offset(pgd, address);         
+       pmd_t *pmd;
+       if (pgd_none(*pgd))
+               return NULL;
+       pmd = pmd_offset(pgd, address);                
+       if (pmd_none(*pmd))
+               return NULL;
        if (pmd_large(*pmd))
                return (pte_t *)pmd;
         return pte_offset_kernel(pmd, address);
@@ -95,12 +100,13 @@ __change_page_attr(struct page *page, pgprot_t prot, struct page **oldpage)
        address = (unsigned long)page_address(page);
 
        kpte = lookup_address(address);
+       if (!kpte)
+               return -EINVAL;
        kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
        if (pgprot_val(prot) != pgprot_val(PAGE_KERNEL)) { 
                if ((pte_val(*kpte) & _PAGE_PSE) == 0) { 
                        pte_t old = *kpte;
                        pte_t standard = mk_pte(page, PAGE_KERNEL); 
-
                        set_pte_atomic(kpte, mk_pte(page, prot)); 
                        if (pte_same(old,standard))
                                atomic_inc(&kpte_page->count);
@@ -108,6 +114,7 @@ __change_page_attr(struct page *page, pgprot_t prot, struct page **oldpage)
                        struct page *split = split_large_page(address, prot); 
                        if (!split)
                                return -ENOMEM;
+                       atomic_inc(&kpte_page->count);
                        set_pmd_pte(kpte,address,mk_pte(split, PAGE_KERNEL));
                }       
        } else if ((pte_val(*kpte) & _PAGE_PSE) == 0) {