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From:   Liam Howlett <liam.howlett@oracle.com>
To:     "maple-tree@lists.infradead.org" <maple-tree@lists.infradead.org>,
        "linux-mm@kvack.org" <linux-mm@kvack.org>,
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        Vlastimil Babka <vbabka@suse.cz>,
        Rik van Riel <riel@surriel.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Michel Lespinasse <walken.cr@gmail.com>,
        Liam Howlett <liam.howlett@oracle.com>
Subject: [PATCH 30/94] mm/mmap: Change find_vma_prev() to use maple tree
Thread-Topic: [PATCH 30/94] mm/mmap: Change find_vma_prev() to use maple tree
Thread-Index: AQHXPEQzICtDe6rRakSmm9wmPE6aTg==
Date:   Wed, 28 Apr 2021 15:36:04 +0000
Message-ID: <20210428153542.2814175-31-Liam.Howlett@Oracle.com>
References: <20210428153542.2814175-1-Liam.Howlett@Oracle.com>
In-Reply-To: <20210428153542.2814175-1-Liam.Howlett@Oracle.com>
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Change the implementation of find_vma_prev to use the new maple tree
data structure.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---
 mm/mmap.c | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 3a9a9aee2f63..0fc81b02935f 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2508,23 +2508,30 @@ struct vm_area_struct *find_vma(struct mm_struct *m=
m, unsigned long addr)
 }
 EXPORT_SYMBOL(find_vma);
=20
-/*
- * Same as find_vma, but also return a pointer to the previous VMA in *ppr=
ev.
+/**
+ * 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
+ *
+ * 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 **pprev)
 {
 	struct vm_area_struct *vma;
+	MA_STATE(mas, &mm->mm_mt, addr, addr);
=20
-	vma =3D find_vma(mm, addr);
-	if (vma) {
-		*pprev =3D vma->vm_prev;
-	} else {
-		struct rb_node *rb_node =3D rb_last(&mm->mm_rb);
+	rcu_read_lock();
+	vma =3D mas_find(&mas, ULONG_MAX);
+	if (!vma)
+		mas_reset(&mas);
=20
-		*pprev =3D rb_node ? rb_entry(rb_node, struct vm_area_struct, vm_rb) : N=
ULL;
-	}
+	*pprev =3D mas_prev(&mas, 0);
+	rcu_read_unlock();
 	return vma;
 }
=20
--=20
2.30.2