patch-2.4.22 linux-2.4.22/arch/s390x/mm/init.c

• Lines: 101
• Date: 2003-08-25 04:44:40.000000000 -0700
• Orig file: linux-2.4.21/arch/s390x/mm/init.c
• Orig date: 2003-06-13 07:51:32.000000000 -0700

diff -urN linux-2.4.21/arch/s390x/mm/init.c linux-2.4.22/arch/s390x/mm/init.c
@@ -45,6 +45,28 @@
 pgd_t swapper_pg_dir[PTRS_PER_PGD] __attribute__((__aligned__(PAGE_SIZE)));
 char  empty_zero_page[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));
 
+static inline int
+__pgd_populate(unsigned long *pgd_slot, unsigned long offset, pmd_t *pmd)
+{
+	if (offset == 0 && 
+	    ((*pgd_slot & _PGD_ENTRY_INV) != 0 ||
+	     (*pgd_slot & _PGD_ENTRY_LEN(2)) == 0)) {
+		/* Set lower pmd, upper pmd is empty. */
+		*pgd_slot = __pa(pmd) | _PGD_ENTRY_MASK |
+				_PGD_ENTRY_OFF(0) | _PGD_ENTRY_LEN(1);
+		return 1;
+	}
+	if (offset == 4 &&
+	    ((*pgd_slot & _PGD_ENTRY_INV) != 0 ||
+	     (*pgd_slot & _PGD_ENTRY_OFF(2)) != 0)) {
+		/* Lower pmd empty, set upper pmd. */
+		*pgd_slot = (__pa(pmd) - 0x2000) | _PGD_ENTRY_MASK |
+				_PGD_ENTRY_OFF(2) | _PGD_ENTRY_LEN(3);
+		return 1;
+	}
+        return 0;
+}
+
 pmd_t *pgd_populate(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmd)
 {
         unsigned long addr = (unsigned long) pgd;
@@ -52,29 +74,42 @@
         unsigned long offset = addr & 4;
 	pmd_t *new, *pmd2;
 	int i;
- 
-        if (offset == 0 && 
-	    ((*pgd_slot & _PGD_ENTRY_INV) != 0 ||
-	     (*pgd_slot & _PGD_ENTRY_LEN(2)) == 0)) {
-                /* Set lower pmd, upper pmd is empty. */
-                *pgd_slot = __pa(pmd) | _PGD_ENTRY_MASK |
-                                _PGD_ENTRY_OFF(0) | _PGD_ENTRY_LEN(1);
-                return pmd;
-        }
-        if (offset == 4 &&
-	    ((*pgd_slot & _PGD_ENTRY_INV) != 0 ||
-	     (*pgd_slot & _PGD_ENTRY_OFF(2)) != 0)) {
-                /* Lower pmd empty, set upper pmd. */
-                *pgd_slot = (__pa(pmd) - 0x2000) | _PGD_ENTRY_MASK |
-                                _PGD_ENTRY_OFF(2) | _PGD_ENTRY_LEN(3);
+
+        /* Check if we can get away with a half-sized pmd. */
+        if (__pgd_populate(pgd_slot, offset, pmd))
                 return pmd;
-        }
+
         /* We have to enlarge the pmd to 16K if we arrive here. */
+        spin_unlock(&mm->page_table_lock);
 	new = (pmd_t *) __get_free_pages(GFP_KERNEL, 2);
-	if (new == NULL) {
+        spin_lock(&mm->page_table_lock);
+
+        /*
+         * Because we dropped the lock, we should re-check the
+         * entry, as somebody else could have populated it..
+         */
+        if (!pgd_none(*pgd)) {
+                if (new)
+                        free_pages((unsigned long) new, 2);
+                pmd_free(pmd);
+                return (pmd_t *) pgd_val(*pgd);
+        }
+
+	if (!new) {
 		pmd_free(pmd);
 		return NULL;
 	}
+
+        /*
+         * Re-check if we can get away with a half-sized pmd. We
+         * dropped the lock so somebody else could have freed the
+         * other half of the pmd.
+         */
+        if (__pgd_populate(pgd_slot, offset, pmd)) {
+                free_pages((unsigned long) new, 2);
+                return pmd;
+        }
+
 	/* Set the PG_arch_1 bit on the first and the third pmd page
            so that pmd_free_fast can recognize pmds that have been
            allocated with an order 2 allocation.  */
@@ -234,11 +269,6 @@
                                         continue;
                                 }
                                 set_pte(pt_dir, pte);
-				if (address < memory_size ) /* do not set storage
-							       key outside the storage
-							       or die */
-					set_access_key(pte); /* switch to our
-								access key */
                                 address += PAGE_SIZE;
                         }
                 }