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>
parent
c1a2b5f6
Please register or sign in to comment