[PATCH] lock PTE before updating it in 440/BookE page fault handler
Fix 44x and BookE page fault handler to correctly lock PTE before
trying to pte_update() it, otherwise this PTE might be swapped out
after pte_present() check but before pte_uptdate() call, resulting in
corrupted PTE. This can happen with enabled preemption and low memory
condition.
Signed-off-by: Eugene Surovegin <ebs@ebshome.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index d296eb6..9062860 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -372,7 +372,7 @@
* the PTE pointer is unmodified if PTE is not found.
*/
int
-get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep)
+get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep, pmd_t **pmdp)
{
pgd_t *pgd;
pmd_t *pmd;
@@ -387,6 +387,8 @@
if (pte) {
retval = 1;
*ptep = pte;
+ if (pmdp)
+ *pmdp = pmd;
/* XXX caller needs to do pte_unmap, yuck */
}
}
@@ -424,7 +426,7 @@
mm = &init_mm;
pa = 0;
- if (get_pteptr(mm, addr, &pte)) {
+ if (get_pteptr(mm, addr, &pte, NULL)) {
pa = (pte_val(*pte) & PAGE_MASK) | (addr & ~PAGE_MASK);
pte_unmap(pte);
}