init.c, pgalloc.h:

  Disable pre-emption around access to pgtable_cache_size, pgd_quicklist,
  and pmd_quicklist.
Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com>
Signed-off-by: Zou Nanhai <nanhai.zou@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/ia64/mm/init.c

@@ -63,6 +63,7 @@ check_pgt_cache (void)
 	low = pgt_cache_water[0];
 	high = pgt_cache_water[1];
 
+	preempt_disable();
 	if (pgtable_cache_size > (u64) high) {
 		do {
 			if (pgd_quicklist)
@@ -71,6 +72,7 @@ check_pgt_cache (void)
 				free_page((unsigned long)pmd_alloc_one_fast(0, 0));
 		} while (pgtable_cache_size > (u64) low);
 	}
+	preempt_enable();
 }
 
 void

include/asm-ia64/pgalloc.h

@@ -37,14 +37,20 @@
 static inline pgd_t*
 pgd_alloc_one_fast (struct mm_struct *mm)
 {
-	unsigned long *ret = pgd_quicklist;
+	unsigned long *ret = NULL;
 
+	preempt_disable();
+
+	ret = pgd_quicklist;
 	if (likely(ret != NULL)) {
 		pgd_quicklist = (unsigned long *)(*ret);
 		ret[0] = 0;
 		--pgtable_cache_size;
 	} else
 		ret = NULL;
+
+	preempt_enable();
+
 	return (pgd_t *) ret;
 }
 
@@ -65,9 +71,11 @@ pgd_alloc (struct mm_struct *mm)
 static inline void
 pgd_free (pgd_t *pgd)
 {
+	preempt_disable();
 	*(unsigned long *)pgd = (unsigned long) pgd_quicklist;
 	pgd_quicklist = (unsigned long *) pgd;
 	++pgtable_cache_size;
+	preempt_enable();
 }
 
 static inline void
@@ -80,13 +88,19 @@ pgd_populate (struct mm_struct *mm, pgd_t *pgd_entry, pmd_t *pmd)
 static inline pmd_t*
 pmd_alloc_one_fast (struct mm_struct *mm, unsigned long addr)
 {
-	unsigned long *ret = (unsigned long *)pmd_quicklist;
+	unsigned long *ret = NULL;
 
+	preempt_disable();
+
+	ret = (unsigned long *)pmd_quicklist;
 	if (likely(ret != NULL)) {
 		pmd_quicklist = (unsigned long *)(*ret);
 		ret[0] = 0;
 		--pgtable_cache_size;
 	}
+
+	preempt_enable();
+
 	return (pmd_t *)ret;
 }
 
@@ -103,9 +117,11 @@ pmd_alloc_one (struct mm_struct *mm, unsigned long addr)
 static inline void
 pmd_free (pmd_t *pmd)
 {
+	preempt_disable();
 	*(unsigned long *)pmd = (unsigned long) pmd_quicklist;
 	pmd_quicklist = (unsigned long *) pmd;
 	++pgtable_cache_size;
+	preempt_enable();
 }
 
 #define __pmd_free_tlb(tlb, pmd)	pmd_free(pmd)