From 68f24b08ee892d47bdef925d676e1ae1ccc316f8 Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Thu, 15 Sep 2016 22:45:48 -0700 Subject: sched/core: Free the stack early if CONFIG_THREAD_INFO_IN_TASK We currently keep every task's stack around until the task_struct itself is freed. This means that we keep the stack allocation alive for longer than necessary and that, under load, we free stacks in big batches whenever RCU drops the last task reference. Neither of these is good for reuse of cache-hot memory, and freeing in batches prevents us from usefully caching small numbers of vmalloced stacks. On architectures that have thread_info on the stack, we can't easily change this, but on architectures that set THREAD_INFO_IN_TASK, we can free it as soon as the task is dead. Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Jann Horn Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/08ca06cde00ebed0046c5d26cbbf3fbb7ef5b812.1474003868.git.luto@kernel.org Signed-off-by: Ingo Molnar --- include/linux/init_task.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include/linux/init_task.h') diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 9c04d44eeb3c..325f649d77ff 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -186,7 +186,9 @@ extern struct task_group root_task_group; #endif #ifdef CONFIG_THREAD_INFO_IN_TASK -# define INIT_TASK_TI(tsk) .thread_info = INIT_THREAD_INFO(tsk), +# define INIT_TASK_TI(tsk) \ + .thread_info = INIT_THREAD_INFO(tsk), \ + .stack_refcount = ATOMIC_INIT(1), #else # define INIT_TASK_TI(tsk) #endif -- cgit v1.2.3