sched/core: Free the stack early if CONFIG_THREAD_INFO_IN_TASK

[karo-tx-linux.git] / kernel / fork.c

diff --git a/kernel/fork.c b/kernel/fork.c
index 0c240fd5beba2c7eefc0df23375ea99291ce76e6..5dd0a516626d9d13ad09c6ad06a01105caa40193 100644 (file)
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -269,11 +269,40 @@ static void account_kernel_stack(struct task_struct *tsk, int account)
        }
 }
 
-void free_task(struct task_struct *tsk)
+static void release_task_stack(struct task_struct *tsk)
 {
        account_kernel_stack(tsk, -1);
        arch_release_thread_stack(tsk->stack);
        free_thread_stack(tsk);
+       tsk->stack = NULL;
+#ifdef CONFIG_VMAP_STACK
+       tsk->stack_vm_area = NULL;
+#endif
+}
+
+#ifdef CONFIG_THREAD_INFO_IN_TASK
+void put_task_stack(struct task_struct *tsk)
+{
+       if (atomic_dec_and_test(&tsk->stack_refcount))
+               release_task_stack(tsk);
+}
+#endif
+
+void free_task(struct task_struct *tsk)
+{
+#ifndef CONFIG_THREAD_INFO_IN_TASK
+       /*
+        * The task is finally done with both the stack and thread_info,
+        * so free both.
+        */
+       release_task_stack(tsk);
+#else
+       /*
+        * If the task had a separate stack allocation, it should be gone
+        * by now.
+        */
+       WARN_ON_ONCE(atomic_read(&tsk->stack_refcount) != 0);
+#endif
        rt_mutex_debug_task_free(tsk);
        ftrace_graph_exit_task(tsk);
        put_seccomp_filter(tsk);
@@ -411,6 +440,9 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
 #ifdef CONFIG_VMAP_STACK
        tsk->stack_vm_area = stack_vm_area;
 #endif
+#ifdef CONFIG_THREAD_INFO_IN_TASK
+       atomic_set(&tsk->stack_refcount, 1);
+#endif
 
        if (err)
                goto free_stack;
@@ -1771,6 +1803,7 @@ bad_fork_cleanup_count:
        atomic_dec(&p->cred->user->processes);
        exit_creds(p);
 bad_fork_free:
+       put_task_stack(p);
        free_task(p);
 fork_out:
        return ERR_PTR(retval);