powerpc: Fix pgtable pmd cache init

Commit 9b081e1080 ("powerpc: port 64 bits pgtable_cache to 32 bits")
mixed up PMD_INDEX_SIZE and PMD_CACHE_INDEX a couple of times. This
resulted in 64s/hash/4k configs to panic at boot with a false positive
error check.

Fix that and simplify error handling by moving the check to the caller.

Fixes: 9b081e1080 ("powerpc: port 64 bits pgtable_cache to 32 bits")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/hugetlbpage.c

@@ -810,12 +810,8 @@ static int __init hugetlbpage_init(void)
 		 * if we have pdshift and shift value same, we don't
 		 * use pgt cache for hugepd.
 		 */
-		if (pdshift > shift) {
+		if (pdshift > shift)
 			pgtable_cache_add(pdshift - shift, NULL);
-			if (!PGT_CACHE(pdshift - shift))
-				panic("hugetlbpage_init(): could not create "
-				      "pgtable cache for %d bit pagesize\n", shift);
-		}
 #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
 		else if (!hugepte_cache) {
 			/*

arch/powerpc/mm/init-common.c

@@ -78,8 +78,12 @@ void pgtable_cache_add(unsigned shift, void (*ctor)(void *))
 	align = max_t(unsigned long, align, minalign);
 	name = kasprintf(GFP_KERNEL, "pgtable-2^%d", shift);
 	new = kmem_cache_create(name, table_size, align, 0, ctor);
+	if (!new)
+		panic("Could not allocate pgtable cache for order %d", shift);
+
 	kfree(name);
 	pgtable_cache[shift - 1] = new;
+
 	pr_debug("Allocated pgtable cache for order %d\n", shift);
 }
 
@@ -88,7 +92,7 @@ void pgtable_cache_init(void)
 {
 	pgtable_cache_add(PGD_INDEX_SIZE, pgd_ctor);
 
-	if (PMD_INDEX_SIZE && !PGT_CACHE(PMD_INDEX_SIZE))
+	if (PMD_CACHE_INDEX && !PGT_CACHE(PMD_CACHE_INDEX))
 		pgtable_cache_add(PMD_CACHE_INDEX, pmd_ctor);
 	/*
 	 * In all current configs, when the PUD index exists it's the
@@ -97,11 +101,4 @@ void pgtable_cache_init(void)
 	 */
 	if (PUD_INDEX_SIZE && !PGT_CACHE(PUD_INDEX_SIZE))
 		pgtable_cache_add(PUD_INDEX_SIZE, pud_ctor);
-
-	if (!PGT_CACHE(PGD_INDEX_SIZE))
-		panic("Couldn't allocate pgd cache");
-	if (PMD_INDEX_SIZE && !PGT_CACHE(PMD_INDEX_SIZE))
-		panic("Couldn't allocate pmd pgtable caches");
-	if (PUD_INDEX_SIZE && !PGT_CACHE(PUD_INDEX_SIZE))
-		panic("Couldn't allocate pud pgtable caches");
 }