Messages in this thread Patch in this message |  | | Subject | Re: [PATCH v4] sched/numa: fix unsafe get_task_struct() in task_numa_assign() | From | Kirill Tkhai <> | Date | Mon, 10 Nov 2014 19:36:30 +0300 |
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В Пн, 10/11/2014 в 19:10 +0300, Kirill Tkhai пишет: > В Пн, 10/11/2014 в 17:03 +0100, Peter Zijlstra пишет: > > On Fri, Nov 07, 2014 at 10:48:27PM -0500, Sasha Levin wrote: > > > [ 829.539183] BUG: spinlock recursion on CPU#10, trinity-c594/11067 > > > [ 829.539203] lock: 0xffff880631dd6b80, .magic: dead4ead, .owner: trinity-c594/11067, .owner_cpu: 13 > > > > Ooh, look at that. CPU#10 vs .owner_cpu: 13 on the _same_ task. > > > > One of those again :/ > > We do not initialyse task_struct::numa_preferred_nid for INIT_TASK. > It there no a problem? >
I mean task_numa_find_cpu(). If a garbage is in cpumask_of_node(env->dst_nid) and cpu is bigger than mask, the check
cpumask_test_cpu(cpu, tsk_cpus_allowed(env->p)
may be true.
So, we dereference wrong rq in task_numa_compare(). It's not rq at all. Strange cpu may be from here. It's just a int number in a wrong memory.
A hypothesis that below may help:
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 826fdf3..a2b4a8a 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1376,6 +1376,9 @@ static void task_numa_find_cpu(struct task_numa_env *env, { int cpu; + if (!node_online(env->dst_nid)) + return; + for_each_cpu(cpu, cpumask_of_node(env->dst_nid)) { /* Skip this CPU if the source task cannot migrate */ if (!cpumask_test_cpu(cpu, tsk_cpus_allowed(env->p)))
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