On Mon, Nov 10, 2014 at 11:00:26PM +0100, Oleg Nesterov wrote: > rcu_read_lock() can not protect p->real_parent if release_task(p) was > already called, change sched_show_task() to check pis_alive() like > other users do. > > Note: we need some helpers to cleanup the code like this. And it seems > that that the usage of cpu_curr(cpu) in dump_cpu_task() is not safe too. > > Signed-off-by: Oleg Nesterov <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]> > --- > kernel/sched/core.c | 4 +++- > 1 files changed, 3 insertions(+), 1 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 240157c..1ec75c9 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -4572,8 +4572,10 @@ void sched_show_task(struct task_struct *p) > #ifdef CONFIG_DEBUG_STACK_USAGE > free = stack_not_used(p); > #endif > + ppid = 0; > rcu_read_lock(); > - ppid = task_pid_nr(rcu_dereference(p->real_parent)); > + if (pid_alive(p)) > + ppid = task_pid_nr(rcu_dereference(p->real_parent)); > rcu_read_unlock(); > printk(KERN_CONT "%5lu %5d %6d 0x%08lx\n", free, > task_pid_nr(p), ppid, > -- > 1.5.5.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
