linux-kernel - [PATCH v2 08/70] mm/mmap: Change find

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Date:   Tue, 12 Jan 2021 11:11:38 -0500
From:   "Liam R. Howlett" <Liam.Howlett@...cle.com>
To:     maple-tree@...ts.infradead.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     Andrew Morton <akpm@...gle.com>, Song Liu <songliubraving@...com>,
        Davidlohr Bueso <dave@...olabs.net>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Jerome Glisse <jglisse@...hat.com>,
        David Rientjes <rientjes@...gle.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Rik van Riel <riel@...riel.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH v2 08/70] mm/mmap: Change find_vma() to use the maple tree

Start using the maple tree to find VMA entries in an mm_struct.

Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 mm/mmap.c | 29 +++++++++++------------------
 1 file changed, 11 insertions(+), 18 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 65789b188c380..ab1cb0efc4c65 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2474,10 +2474,17 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 
 EXPORT_SYMBOL(get_unmapped_area);
 
-/* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
+/**
+ * find_vma() - Find the VMA for a given address, or the next vma.  May return
+ * NULL in the case of no vma at addr or above
+ * @mm The mm_struct to check
+ * @addr: The address
+ *
+ * Returns: The VMA assoicated 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(struct mm_struct *mm, unsigned long addr)
 {
-	struct rb_node *rb_node;
 	struct vm_area_struct *vma;
 
 	/* Check the cache first. */
@@ -2485,24 +2492,10 @@ struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 	if (likely(vma))
 		return vma;
 
-	rb_node = mm->mm_rb.rb_node;
-
-	while (rb_node) {
-		struct vm_area_struct *tmp;
-
-		tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb);
-
-		if (tmp->vm_end > addr) {
-			vma = tmp;
-			if (tmp->vm_start <= addr)
-				break;
-			rb_node = rb_node->rb_left;
-		} else
-			rb_node = rb_node->rb_right;
-	}
-
+	vma = mt_find(&mm->mm_mt, &addr, ULONG_MAX);
 	if (vma)
 		vmacache_update(addr, vma);
+
 	return vma;
 }
 EXPORT_SYMBOL(find_vma);
-- 
2.28.0