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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2017-03-09 17:24:08 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-03-09 11:48:48 -0800
commit90eceff1a375f6ffa78caf8654e787c0a8a591ef (patch)
treea3fa46c32dc6b45dc99559eafa937ff4c4d2f1d7
parentc2febafc67734a62196c1b9dfba926412d4077ba (diff)
mm: introduce __p4d_alloc()
For full 5-level paging we need a helper to allocate p4d page table. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/memory.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 7f1c2163b3ce..235ba51b2fbf 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3906,6 +3906,29 @@ int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
}
EXPORT_SYMBOL_GPL(handle_mm_fault);
+#ifndef __PAGETABLE_P4D_FOLDED
+/*
+ * Allocate p4d page table.
+ * We've already handled the fast-path in-line.
+ */
+int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
+{
+ p4d_t *new = p4d_alloc_one(mm, address);
+ if (!new)
+ return -ENOMEM;
+
+ smp_wmb(); /* See comment in __pte_alloc */
+
+ spin_lock(&mm->page_table_lock);
+ if (pgd_present(*pgd)) /* Another has populated it */
+ p4d_free(mm, new);
+ else
+ pgd_populate(mm, pgd, new);
+ spin_unlock(&mm->page_table_lock);
+ return 0;
+}
+#endif /* __PAGETABLE_P4D_FOLDED */
+
#ifndef __PAGETABLE_PUD_FOLDED
/*
* Allocate page upper directory.