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| author | Thomas Gleixner <tglx@linutronix.de> | 2017-05-16 20:42:32 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2017-05-23 10:01:34 +0200 |
| commit | 8fb12156b8db61af3d49f3e5e104568494581d1f (patch) | |
| tree | 7a0bbfa7ff1a094ac918e8630f0993faec9c1173 /init | |
| parent | 8655d5497735b288f8a9b458bd22e7d1bf95bb61 (diff) | |
| download | lwn-8fb12156b8db61af3d49f3e5e104568494581d1f.tar.gz lwn-8fb12156b8db61af3d49f3e5e104568494581d1f.zip | |
init: Pin init task to the boot CPU, initially
Some of the boot code in init_kernel_freeable() which runs before SMP
bringup assumes (rightfully) that it runs on the boot CPU and therefore can
use smp_processor_id() in preemptible context.
That works so far because the smp_processor_id() check starts to be
effective after smp bringup. That's just wrong. Starting with SMP bringup
and the ability to move threads around, smp_processor_id() in preemptible
context is broken.
Aside of that it does not make sense to allow init to run on all CPUs
before sched_smp_init() has been run.
Pin the init to the boot CPU so the existing code can continue to use
smp_processor_id() without triggering the checks when the enabling of those
checks starts earlier.
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/20170516184734.943149935@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'init')
| -rw-r--r-- | init/main.c | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/init/main.c b/init/main.c index f866510472d7..badae3bf08f1 100644 --- a/init/main.c +++ b/init/main.c @@ -389,6 +389,7 @@ static __initdata DECLARE_COMPLETION(kthreadd_done); static noinline void __ref rest_init(void) { + struct task_struct *tsk; int pid; rcu_scheduler_starting(); @@ -397,7 +398,17 @@ static noinline void __ref rest_init(void) * the init task will end up wanting to create kthreads, which, if * we schedule it before we create kthreadd, will OOPS. */ - kernel_thread(kernel_init, NULL, CLONE_FS); + pid = kernel_thread(kernel_init, NULL, CLONE_FS); + /* + * Pin init on the boot CPU. Task migration is not properly working + * until sched_init_smp() has been run. It will set the allowed + * CPUs for init to the non isolated CPUs. + */ + rcu_read_lock(); + tsk = find_task_by_pid_ns(pid, &init_pid_ns); + set_cpus_allowed_ptr(tsk, cpumask_of(smp_processor_id())); + rcu_read_unlock(); + numa_default_policy(); pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES); rcu_read_lock(); @@ -1015,10 +1026,6 @@ static noinline void __init kernel_init_freeable(void) * init can allocate pages on any node */ set_mems_allowed(node_states[N_MEMORY]); - /* - * init can run on any cpu. - */ - set_cpus_allowed_ptr(current, cpu_all_mask); cad_pid = task_pid(current); |