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authorOleg Nesterov <oleg@redhat.com>2014-12-10 15:45:21 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-10 17:41:09 -0800
commita90e984c8a660dd58894a68cc5d9d5cd457d5796 (patch)
treed6426e282d133edbf4cded526bd8f9f882d59cae /kernel
parentabdba6e9ea6d3903c2b0618db720e17b3c1c705c (diff)
downloadlinux-a90e984c8a660dd58894a68cc5d9d5cd457d5796.tar.bz2
sched_show_task: fix unsafe usage of ->real_parent
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 <oleg@redhat.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Cc: Sterling Alexander <stalexan@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Roland McGrath <roland@hack.frob.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index bb398c0c5f08..b5797b78add6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4527,8 +4527,10 @@ 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,