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Subject[PATCH 1/2] Take rcu read lock when iterating through thread group
Date
Protect the iteration through thread group with rcu_read_lock when
looking for tasks in the group that use the current vma as
stack. Thanks KOSAKI Motohiro (kosaki.motohiro@gmail.com) for pointing
it out.

Signed-off-by: Siddhesh Poyarekar <siddhesh.poyarekar@gmail.com>
---
mm/memory.c | 15 +++++++++++----
1 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 601a920..a88b764 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3915,20 +3915,27 @@ void print_vma_addr(char *prefix, unsigned long ip)
* just check in the current task.
*/
int vm_is_stack(struct task_struct *task,
- struct vm_area_struct *vma, int in_group)
+ struct vm_area_struct *vma, int in_group)
{
+ int ret = 0;
+
if (vm_is_stack_for_task(task, vma))
return 1;

if (in_group) {
struct task_struct *t = task;
+ rcu_read_lock();
while_each_thread(task, t) {
- if (vm_is_stack_for_task(t, vma))
- return 1;
+ if (vm_is_stack_for_task(t, vma)) {
+ ret = 1;
+ goto done;
+ }
}
}

- return 0;
+done:
+ rcu_read_unlock();
+ return ret;
}

#ifdef CONFIG_PROVE_LOCKING
--
1.7.7.4


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