diff options
authorOleg Nesterov <oleg@redhat.com>2009-06-18 16:49:11 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-19 16:46:06 -0700
commitbefca96779b0259ac8fad0183e748a62935c39cb (patch)
parente6229bec25be4ba00f31dd26e25721cc96c22262 (diff)
ptrace: wait_task_zombie: do not account traced sub-threads
The bug is ancient. If we trace the sub-thread of our natural child and this sub-thread exits, we update parent->signal->cxxx fields. But we should not do this until the whole thread-group exits, otherwise we account this thread (and all other live threads) twice. Add the task_detached() check. No need to check thread_group_empty(), wait_consider_task()->delay_group_leader() already did this. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Roland McGrath <roland@redhat.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Vitaly Mayatskikh <vmayatsk@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index 13ae64001fe..628d41f0dd5 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1197,8 +1197,11 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
traced = ptrace_reparented(p);
- if (likely(!traced)) {
+ /*
+ * It can be ptraced but not reparented, check
+ * !task_detached() to filter out sub-threads.
+ */
+ if (likely(!traced) && likely(!task_detached(p))) {
struct signal_struct *psig;
struct signal_struct *sig;