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 <o...@redhat.com>
---
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
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