[POWERPC] Don't use SLAB/SLUB for PTE pages

The SLUB allocator relies on struct page fields first_page and slab,
overwritten by ptl when SPLIT_PTLOCK: so the SLUB allocator cannot then
be used for the lowest level of pagetable pages.  This was obstructing
SLUB on PowerPC, which uses kmem_caches for its pagetables.  So convert
its pte level to use normal gfp pages (whereas pmd, pud and 64k-page pgd
want partpages, so continue to use kmem_caches for pmd, pud and pgd).

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

2 files changed, 6 insertions, 24 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index ecd459dd1baf..ccc5410af996 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -120,19 +120,6 @@ config GENERIC_BUG
 config SYS_SUPPORTS_APM_EMULATION
         bool
 
-#
-# Powerpc uses the slab allocator to manage its ptes and the
-# page structs of ptes are used for splitting the page table
-# lock for configurations supporting more than SPLIT_PTLOCK_CPUS.
-#
-# In that special configuration the page structs of slabs are modified.
-# This setting disables the selection of SLUB as a slab allocator.
-#
-config ARCH_USES_SLAB_PAGE_STRUCT
-        bool
-        default y
-        depends on SPLIT_PTLOCK_CPUS <= NR_CPUS
-
 config DEFAULT_UIMAGE
         bool
         help
diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index fe1fe852181a..7312a265545f 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -146,21 +146,16 @@ static void zero_ctor(void *addr, struct kmem_cache *cache, unsigned long flags)
         memset(addr, 0, kmem_cache_size(cache));
 }
 
-#ifdef CONFIG_PPC_64K_PAGES
-static const unsigned int pgtable_cache_size[3] = {
-        PTE_TABLE_SIZE, PMD_TABLE_SIZE, PGD_TABLE_SIZE
-};
-static const char *pgtable_cache_name[ARRAY_SIZE(pgtable_cache_size)] = {
-        "pte_pmd_cache", "pmd_cache", "pgd_cache",
-};
-#else
 static const unsigned int pgtable_cache_size[2] = {
-        PTE_TABLE_SIZE, PMD_TABLE_SIZE
+        PGD_TABLE_SIZE, PMD_TABLE_SIZE
 };
 static const char *pgtable_cache_name[ARRAY_SIZE(pgtable_cache_size)] = {
-        "pgd_pte_cache", "pud_pmd_cache",
-};
+#ifdef CONFIG_PPC_64K_PAGES
+        "pgd_cache", "pmd_cache",
+#else
+        "pgd_cache", "pud_pmd_cache",
 #endif /* CONFIG_PPC_64K_PAGES */
+};
 
 #ifdef CONFIG_HUGETLB_PAGE
 /* Hugepages need one extra cache, initialized in hugetlbpage.c.  We