x86, mm: enable split page table lock for PMD level

Enable PMD split page table lock for X86_64 and PAE.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Alex Thorlton <athorlton@sgi.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dave Jones <davej@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Robin Holt <robinmholt@gmail.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Hugh Dickins <hughd@google.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 14 insertions, 1 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6e3e1cb3f6a0..af5513e5798a 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1885,6 +1885,10 @@ config USE_PERCPU_NUMA_NODE_ID
         def_bool y
         depends on NUMA
 
+config ARCH_ENABLE_SPLIT_PMD_PTLOCK
+        def_bool y
+        depends on X86_64 || X86_PAE
+
 menu "Power management and ACPI options"
 
 config ARCH_HIBERNATION_HEADER
diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h
index b4389a468fb6..c4412e972bbd 100644
--- a/arch/x86/include/asm/pgalloc.h
+++ b/arch/x86/include/asm/pgalloc.h
@@ -80,12 +80,21 @@ static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
 #if PAGETABLE_LEVELS > 2
 static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
 {
-        return (pmd_t *)get_zeroed_page(GFP_KERNEL|__GFP_REPEAT);
+        struct page *page;
+        page = alloc_pages(GFP_KERNEL | __GFP_REPEAT | __GFP_ZERO, 0);
+        if (!page)
+                return NULL;
+        if (!pgtable_pmd_page_ctor(page)) {
+                __free_pages(page, 0);
+                return NULL;
+        }
+        return (pmd_t *)page_address(page);
 }
 
 static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
 {
         BUG_ON((unsigned long)pmd & (PAGE_SIZE-1));
+        pgtable_pmd_page_dtor(virt_to_page(pmd));
         free_page((unsigned long)pmd);
 }