diff mbox series

[v9,12/69] mm/mmap: use the maple tree for find_vma_prev() instead of the rbtree

Message ID 20220504010716.661115-14-Liam.Howlett@oracle.com (mailing list archive)
State New
Headers show
Series Maple Tree v9 | expand

Commit Message

Liam R. Howlett May 4, 2022, 1:07 a.m. UTC
From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>

Use the maple tree's advanced API and a maple state to walk the tree for
the entry at the address of the next vma, then use the maple state to walk
back one entry to find the previous entry.

Add kernel documentation comments for this API.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
---
 mm/mmap.c | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)
diff mbox series

Patch

diff --git a/mm/mmap.c b/mm/mmap.c
index f582478c83b1..7ab07c67da71 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2489,23 +2489,30 @@  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.
+/**
+ * find_vma_prev() - Find the VMA for a given address, or the next vma and
+ * set %pprev to the previous VMA, if any.
+ * @mm: The mm_struct to check
+ * @addr: The address
+ * @pprev: The pointer to set to the previous VMA
+ *
+ * Note that RCU lock is missing here since the external mmap_lock() is used
+ * instead.
+ *
+ * Returns: The VMA associated with @addr, or the next vma.
+ * May return %NULL in the case of no vma at addr or above.
  */
 struct vm_area_struct *
 find_vma_prev(struct mm_struct *mm, unsigned long addr,
 			struct vm_area_struct **pprev)
 {
 	struct vm_area_struct *vma;
+	MA_STATE(mas, &mm->mm_mt, addr, addr);
 
-	vma = find_vma(mm, addr);
-	if (vma) {
-		*pprev = vma->vm_prev;
-	} else {
-		struct rb_node *rb_node = rb_last(&mm->mm_rb);
-
-		*pprev = rb_node ? rb_entry(rb_node, struct vm_area_struct, vm_rb) : NULL;
-	}
+	vma = mas_walk(&mas);
+	*pprev = mas_prev(&mas, 0);
+	if (!vma)
+		vma = mas_next(&mas, ULONG_MAX);
 	return vma;
 }