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authorKirill Tkhai <ktkhai@parallels.com>2014-11-11 12:46:29 +0300
committerIngo Molnar <mingo@kernel.org>2014-11-16 10:59:01 +0100
commitd8b163c4c657478ef33c082cff78d03a4ca07bb2 (patch)
tree9653413e705b55c48c23bb57bf6c21bdf774a40a /include/linux/init_task.h
parentc1a2b5f6293caa14804adca1840eeea1e8f6b322 (diff)
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 <ktkhai@parallels.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Eric Paris <eparis@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Sergey Dyasly <dserrg@gmail.com> Link: http://lkml.kernel.org/r/1415699189.15631.6.camel@tkhai Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/init_task.h')
-rw-r--r--include/linux/init_task.h10
1 files changed, 10 insertions, 0 deletions
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) \
}