rcu_read_lock is required by grabbing the task refcount but it's not
needed for ptrace_may_access. So we could release the rcu lock after
task refcount is successfully grabbed to reduce the rcu holding time.
Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
---
mm/migrate.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index a3d8c2be2631..d8aae6c75990 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1907,17 +1907,16 @@ static struct mm_struct *find_mm_struct(pid_t pid, nodemask_t *mem_nodes)
return ERR_PTR(-ESRCH);
}
get_task_struct(task);
+ rcu_read_unlock();
/*
* Check if this process has the right to modify the specified
* process. Use the regular "ptrace_may_access()" checks.
*/
if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
- rcu_read_unlock();
mm = ERR_PTR(-EPERM);
goto out;
}
- rcu_read_unlock();
mm = ERR_PTR(security_task_movememory(task));
if (IS_ERR(mm))
--
2.23.0
