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Commit 6bd4837d authored by KOSAKI Motohiro's avatar KOSAKI Motohiro Committed by Linus Torvalds
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mm: simplify find_vma_prev() 



commit 297c5eee ("mm: make the vma list be doubly linked") added the
vm_prev member to vm_area_struct.  We can simplify find_vma_prev() by
using it.  Also, this change helps to improve page fault performance
because it has stronger locality of reference.

Signed-off-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Shaohua Li <shaohua.li@intel.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 948f017b

mm/mmap.c

+8 −28
Original line number Diff line number Diff line
@@ -1603,39 +1603,19 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 


EXPORT_SYMBOL(find_vma);



/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */

/*

 * Same as find_vma, but also return a pointer to the previous VMA in *pprev.

 * Note: pprev is set to NULL when return value is NULL.

 */

struct vm_area_struct *

find_vma_prev(struct mm_struct *mm, unsigned long addr,

			struct vm_area_struct **pprev)

{

	struct vm_area_struct *vma = NULL, *prev = NULL;

	struct rb_node *rb_node;

	if (!mm)

		goto out;



	/* Guard against addr being lower than the first VMA */

	vma = mm->mmap;



	/* Go through the RB tree quickly. */

	rb_node = mm->mm_rb.rb_node;



	while (rb_node) {

		struct vm_area_struct *vma_tmp;

		vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);



		if (addr < vma_tmp->vm_end) {

			rb_node = rb_node->rb_left;

		} else {

			prev = vma_tmp;

			if (!prev->vm_next || (addr < prev->vm_next->vm_end))

				break;

			rb_node = rb_node->rb_right;

		}

	}

	struct vm_area_struct *vma;



out:

	*pprev = prev;

	return prev ? prev->vm_next : vma;

	vma = find_vma(mm, addr);

	*pprev = vma ? vma->vm_prev : NULL;

	return vma;

}



/*