From d8b163c4c657478ef33c082cff78d03a4ca07bb2 Mon Sep 17 00:00:00 2001 From: Kirill Tkhai Date: Tue, 11 Nov 2014 12:46:29 +0300 Subject: [PATCH] sched/numa: Init numa balancing fields of init_task We do not initialize init_task.numa_preferred_nid, but this value is inherited by userspace "init" process: rest_init()->kernel_thread(kernel_init)->do_fork(CLONE_VM); __sched_fork() { if (clone_flags & CLONE_VM) p->numa_preferred_nid = current->numa_preferred_nid; else p->numa_preferred_nid = -1; } kernel_init() becomes userspace "init" process. So, we propagate garbage nid to userspace, and it may be used during numa balancing. Currently, we do not have reports about this brings a problem, but it seem we should set it for sure. Even if init_task.numa_preferred_nid is zero, we may meet a weird configuration without nid#0. On sparc64, where processors are numbered physically, I saw a machine without cpu#1, while cpu#2 existed. Possible, something similar may be with numa nodes. So, let's initialize it and be sure we're safe. Signed-off-by: Kirill Tkhai Signed-off-by: Peter Zijlstra (Intel) Cc: Eric Paris Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Paul E. McKenney Cc: Sergey Dyasly Link: http://lkml.kernel.org/r/1415699189.15631.6.camel@tkhai Signed-off-by: Ingo Molnar --- include/linux/init_task.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 77fc43f8fb72..5f30ac8c82bc 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -166,6 +166,15 @@ extern struct task_group root_task_group; # define INIT_RT_MUTEXES(tsk) #endif +#ifdef CONFIG_NUMA_BALANCING +# define INIT_NUMA_BALANCING(tsk) \ + .numa_preferred_nid = -1, \ + .numa_group = NULL, \ + .numa_faults = NULL, +#else +# define INIT_NUMA_BALANCING(tsk) +#endif + /* * INIT_TASK is used to set up the first task table, touch at * your own risk!. Base=0, limit=0x1fffff (=2MB) @@ -237,6 +246,7 @@ extern struct task_group root_task_group; INIT_CPUSET_SEQ(tsk) \ INIT_RT_MUTEXES(tsk) \ INIT_VTIME(tsk) \ + INIT_NUMA_BALANCING(tsk) \ } -- 2.39.5