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mm: introduce __p4d_alloc()

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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>
This commit is contained in:
Kirill A. Shutemov 2017-03-09 17:24:08 +03:00 committed by Linus Torvalds
parent c2febafc67
commit 90eceff1a3
1 changed files with 23 additions and 0 deletions
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23
mm/memory.c
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@ -3906,6 +3906,29 @@ int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
} }
EXPORT_SYMBOL_GPL(handle_mm_fault); 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 #ifndef __PAGETABLE_PUD_FOLDED
/* /*
* Allocate page upper directory. * Allocate page upper directory.