linux-kernel - [PATCH v3 55/66] mm/mprotect: Use maple tree navigation instead of vma linked list

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Date:   Tue, 5 Oct 2021 01:31:07 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Hildenbrand <david@...hat.com>,
        Douglas Gilbert <dgilbert@...erlog.com>
CC:     Song Liu <songliubraving@...com>,
        Davidlohr Bueso <dave@...olabs.net>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        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 v3 55/66] mm/mprotect: Use maple tree navigation instead of
 vma linked list

From: "Liam R. Howlett" <Liam.Howlett@...cle.com>

Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 mm/mprotect.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 883e2cc85cad..a4041d2c0dfb 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -528,6 +528,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
 	const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
 	const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
 				(prot & PROT_READ);
+	MA_STATE(mas, &current->mm->mm_mt, start, start);
 
 	start = untagged_addr(start);
 
@@ -559,11 +560,15 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
 	if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
 		goto out;
 
-	vma = find_vma(current->mm, start);
+	rcu_read_lock();
+	vma = mas_find(&mas, ULONG_MAX);
 	error = -ENOMEM;
-	if (!vma)
+	if (!vma) {
+		rcu_read_unlock();
 		goto out;
-	prev = vma->vm_prev;
+	}
+	prev = mas_prev(&mas, 0);
+	rcu_read_unlock();
 	if (unlikely(grows & PROT_GROWSDOWN)) {
 		if (vma->vm_start >= end)
 			goto out;
@@ -644,7 +649,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
 		if (nstart >= end)
 			goto out;
 
-		vma = prev->vm_next;
+		vma = vma_next(current->mm, prev);
 		if (!vma || vma->vm_start != nstart) {
 			error = -ENOMEM;
 			goto out;
-- 
2.30.2