asm-generic: pgalloc: provide generic pmd_alloc_one() and pmd_free_one()

For most architectures that support >2 levels of page tables,
pmd_alloc_one() is a wrapper for __get_free_pages(), sometimes with
__GFP_ZERO and sometimes followed by memset(0) instead.

More elaborate versions on arm64 and x86 account memory for the user page
tables and call to pgtable_pmd_page_ctor() as the part of PMD page
initialization.

Move the arm64 version to include/asm-generic/pgalloc.h and use the
generic version on several architectures.

The pgtable_pmd_page_ctor() is a NOP when ARCH_ENABLE_SPLIT_PMD_PTLOCK is
not enabled, so there is no functional change for most architectures
except of the addition of __GFP_ACCOUNT for allocation of user page
tables.

The pmd_free() is a wrapper for free_page() in all the cases, so no
functional change here.

Signed-off-by: Mike Rapoport <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Pekka Enberg <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Abdul Haleem <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Max Filippov <[email protected]>
Cc: Peter Zijlstra (Intel) <[email protected]>
Cc: Satheesh Rajendran <[email protected]>
Cc: Stafford Horne <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 0 insertions, 12 deletions

diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index c2ff76c8981e..a4accb14cbd5 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -201,18 +201,6 @@ void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 	free_page((unsigned long) pgd);
 }
 
-#ifdef CONFIG_3_LEVEL_PGTABLES
-pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
-{
-	pmd_t *pmd = (pmd_t *) __get_free_page(GFP_KERNEL);
-
-	if (pmd)
-		memset(pmd, 0, PAGE_SIZE);
-
-	return pmd;
-}
-#endif
-
 void *uml_kmalloc(int size, int flags)
 {
 	return kmalloc(size, flags);