From: Sebastian Andrzej Siewior Date: Mon, 21 Nov 2016 19:31:08 +0100 Subject: [PATCH] kernel/sched: move stack + kprobe clean up to __put_task_struct() Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.4/older/patches-5.4.3-rt1.tar.xz There is no need to free the stack before the task struct (except for reasons mentioned in commit 68f24b08ee89 ("sched/core: Free the stack early if CONFIG_THREAD_INFO_IN_TASK")). This also comes handy on -RT because we can't free memory in preempt disabled region. vfree_atomic() delays the memory cleanup to a worker. Since we move everything to the RCU callback, we can also free it immediately. Cc: stable-rt@vger.kernel.org #for kprobe_flush_task() Signed-off-by: Sebastian Andrzej Siewior --- kernel/fork.c | 12 +++++++++++- kernel/sched/core.c | 9 --------- 2 files changed, 11 insertions(+), 10 deletions(-) --- a/kernel/fork.c +++ b/kernel/fork.c @@ -43,6 +43,7 @@ #include #include #include +#include #include #include #include @@ -289,7 +290,7 @@ static inline void free_thread_stack(str return; } - vfree_atomic(tsk->stack); + vfree(tsk->stack); return; } #endif @@ -750,6 +751,15 @@ void __put_task_struct(struct task_struc WARN_ON(refcount_read(&tsk->usage)); WARN_ON(tsk == current); + /* + * Remove function-return probe instances associated with this + * task and put them back on the free list. + */ + kprobe_flush_task(tsk); + + /* Task is done with its stack. */ + put_task_stack(tsk); + cgroup_free(tsk); task_numa_free(tsk, true); security_task_free(tsk); --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3253,15 +3253,6 @@ static struct rq *finish_task_switch(str if (prev->sched_class->task_dead) prev->sched_class->task_dead(prev); - /* - * Remove function-return probe instances associated with this - * task and put them back on the free list. - */ - kprobe_flush_task(prev); - - /* Task is done with its stack. */ - put_task_stack(prev); - put_task_struct_rcu_user(prev); }