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Commit 517e2263 authored by Hugh Dickins's avatar Hugh Dickins Committed by Paul Mackerras
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[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: default avatarHugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent f1fa74f4

arch/powerpc/Kconfig

+0 −13
Original line number Diff line number Diff line
@@ -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

arch/powerpc/mm/init_64.c

+6 −11
Original line number Diff line number Diff line
@@ -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

include/asm-powerpc/pgalloc-64.h

+13 −18
Original line number Diff line number Diff line
@@ -14,18 +14,11 @@ 


extern struct kmem_cache *pgtable_cache[];



#ifdef CONFIG_PPC_64K_PAGES

#define PTE_CACHE_NUM	0

#define PMD_CACHE_NUM	1

#define PGD_CACHE_NUM	2

#define HUGEPTE_CACHE_NUM 3

#else

#define PTE_CACHE_NUM	0

#define PMD_CACHE_NUM	1

#define PUD_CACHE_NUM	1

#define PGD_CACHE_NUM		0

#define PUD_CACHE_NUM		1

#define PMD_CACHE_NUM		1

#define HUGEPTE_CACHE_NUM	2

#endif

#define PTE_NONCACHE_NUM	3  /* from GFP rather than kmem_cache */



static inline pgd_t *pgd_alloc(struct mm_struct *mm)

{
@@ -91,8 +84,7 @@ static inline void pmd_free(pmd_t *pmd) 
static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm,

					  unsigned long address)

{

	return kmem_cache_alloc(pgtable_cache[PTE_CACHE_NUM],

				GFP_KERNEL|__GFP_REPEAT);

        return (pte_t *)__get_free_page(GFP_KERNEL | __GFP_REPEAT | __GFP_ZERO);

}



static inline struct page *pte_alloc_one(struct mm_struct *mm,
@@ -103,12 +95,12 @@ static inline struct page *pte_alloc_one(struct mm_struct *mm, 


static inline void pte_free_kernel(pte_t *pte)

{

	kmem_cache_free(pgtable_cache[PTE_CACHE_NUM], pte);

	free_page((unsigned long)pte);

}



static inline void pte_free(struct page *ptepage)

{

	pte_free_kernel(page_address(ptepage));

	__free_page(ptepage);

}



#define PGF_CACHENUM_MASK	0x3
@@ -130,6 +122,9 @@ static inline void pgtable_free(pgtable_free_t pgf) 
	void *p = (void *)(pgf.val & ~PGF_CACHENUM_MASK);

	int cachenum = pgf.val & PGF_CACHENUM_MASK;



	if (cachenum == PTE_NONCACHE_NUM)

		free_page((unsigned long)p);

	else

		kmem_cache_free(pgtable_cache[cachenum], p);

}
@@ -137,7 +132,7 @@ extern void pgtable_free_tlb(struct mmu_gather *tlb, pgtable_free_t pgf); 


#define __pte_free_tlb(tlb, ptepage)	\

	pgtable_free_tlb(tlb, pgtable_free_cache(page_address(ptepage), \

		PTE_CACHE_NUM, PTE_TABLE_SIZE-1))

		PTE_NONCACHE_NUM, PTE_TABLE_SIZE-1))

#define __pmd_free_tlb(tlb, pmd) 	\

	pgtable_free_tlb(tlb, pgtable_free_cache(pmd, \

		PMD_CACHE_NUM, PMD_TABLE_SIZE-1))