From 591a18db7f56cc48c867594fb5981bbb6b008a9e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?T=C3=B6r=C3=B6k=20Edwin?= <edwintorok@gmail.com>
Date: Sun, 23 Nov 2008 12:39:07 +0200
Subject: [PATCH] --- yaml --- r: 121189 b: refs/heads/master c:
 cffa10aecb6891f090a4d53a075bc40c082c45fc h: refs/heads/master i:   121187:
 ab5236783b630aedb74aed63b63eee2581471417 v: v3

---
 [refs]                     | 2 +-
 trunk/kernel/trace/trace.c | 9 ++++++---
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/[refs] b/[refs]
index 0c082d2fc133..8d315b84abb1 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8d7c6a96164651dbbab449ef0b5c20ae1f76a3a1
+refs/heads/master: cffa10aecb6891f090a4d53a075bc40c082c45fc
diff --git a/trunk/kernel/trace/trace.c b/trunk/kernel/trace/trace.c
index dedf35f36971..4c3bd82cec49 100644
--- a/trunk/kernel/trace/trace.c
+++ b/trunk/kernel/trace/trace.c
@@ -1462,11 +1462,15 @@ static inline int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm,
 	int ret = 1;
 
 	if (mm) {
-		const struct vm_area_struct *vma = find_vma(mm, ip);
+		const struct vm_area_struct *vma;
+
+		down_read(&mm->mmap_sem);
+		vma = find_vma(mm, ip);
 		if (vma) {
 			file = vma->vm_file;
 			vmstart = vma->vm_start;
 		}
+		up_read(&mm->mmap_sem);
 	}
 	if (file) {
 		ret = trace_seq_path(s, &file->f_path);
@@ -1494,10 +1498,9 @@ seq_print_userip_objs(const struct userstack_entry *entry, struct trace_seq *s,
 		 */
 		rcu_read_lock();
 		task = find_task_by_vpid(entry->ent.tgid);
-		rcu_read_unlock();
-
 		if (task)
 			mm = get_task_mm(task);
+		rcu_read_unlock();
 	}
 
 	for (i = 0; i < FTRACE_STACK_ENTRIES; i++) {