On 05/22/2014 05:56 PM, tip-bot for Lai Jiangshan wrote:
> Commit-ID: 6acbfb96976fc3350e30d964acb1dbbdf876d55e
> Gitweb: http://git.kernel.org/tip/6acbfb96976fc3350e30d964acb1dbbdf876d55e
> Author: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
> AuthorDate: Fri, 16 May 2014 11:50:42 +0800
> Committer: Ingo Molnar <mingo@xxxxxxxxxx>
> CommitDate: Thu, 22 May 2014 10:21:31 +0200
>
> sched: Fix hotplug vs. set_cpus_allowed_ptr()
>
> Lai found that:
>
> WARNING: CPU: 1 PID: 13 at arch/x86/kernel/smp.c:124 native_smp_send_reschedule+0x2d/0x4b()
> ...
> migration_cpu_stop+0x1d/0x22
>
> was caused by set_cpus_allowed_ptr() assuming that cpu_active_mask is
> always a sub-set of cpu_online_mask.
>
> This isn't true since 5fbd036b552f ("sched: Cleanup cpu_active madness").
>
> So set active and online at the same time to avoid this particular
> problem.
>
> Fixes: 5fbd036b552f ("sched: Cleanup cpu_active madness")
> Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
> Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Gautham R. Shenoy <ego@xxxxxxxxxxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Michael wang <wangyun@xxxxxxxxxxxxxxxxxx>
> Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Cc: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
> Cc: Toshi Kani <toshi.kani@xxxxxx>
> Link: http://lkml.kernel.org/r/53758B12.8060609@xxxxxxxxxxxxxx
> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx>
Regards,
Srivatsa S. Bhat
> ---
> kernel/cpu.c | 6 ++++--
> kernel/sched/core.c | 1 -
> 2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/cpu.c b/kernel/cpu.c
> index a9e710e..247979a 100644
> --- a/kernel/cpu.c
> +++ b/kernel/cpu.c
> @@ -726,10 +726,12 @@ void set_cpu_present(unsigned int cpu, bool present)
>
> void set_cpu_online(unsigned int cpu, bool online)
> {
> - if (online)
> + if (online) {
> cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits));
> - else
> + cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits));
> + } else {
> cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits));
> + }
> }
>
> void set_cpu_active(unsigned int cpu, bool active)
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 44e00ab..86f3890 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -5076,7 +5076,6 @@ static int sched_cpu_active(struct notifier_block *nfb,
> unsigned long action, void *hcpu)
> {
> switch (action & ~CPU_TASKS_FROZEN) {
> - case CPU_STARTING:
> case CPU_DOWN_FAILED:
> set_cpu_active((long)hcpu, true);
> return NOTIFY_OK;
>
--
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