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| author | Oleg Nesterov <oleg@redhat.com> | 2014-12-10 15:45:21 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-10 17:41:09 -0800 |
| commit | a90e984c8a660dd58894a68cc5d9d5cd457d5796 (patch) | |
| tree | d6426e282d133edbf4cded526bd8f9f882d59cae /kernel | |
| parent | abdba6e9ea6d3903c2b0618db720e17b3c1c705c (diff) | |
| download | linux-a90e984c8a660dd58894a68cc5d9d5cd457d5796.tar.gz | |
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.c | 4 |
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, |