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-rw-r--r--include/linux/sched.h2
-rw-r--r--kernel/exit.c1
-rw-r--r--kernel/sched/auto_group.c19
3 files changed, 22 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 348f51b0ec92..e9c009dc3a4a 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2567,6 +2567,7 @@ extern void sched_autogroup_create_attach(struct task_struct *p);
extern void sched_autogroup_detach(struct task_struct *p);
extern void sched_autogroup_fork(struct signal_struct *sig);
extern void sched_autogroup_exit(struct signal_struct *sig);
+extern void sched_autogroup_exit_task(struct task_struct *p);
#ifdef CONFIG_PROC_FS
extern void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m);
extern int proc_sched_autogroup_set_nice(struct task_struct *p, int nice);
@@ -2576,6 +2577,7 @@ static inline void sched_autogroup_create_attach(struct task_struct *p) { }
static inline void sched_autogroup_detach(struct task_struct *p) { }
static inline void sched_autogroup_fork(struct signal_struct *sig) { }
static inline void sched_autogroup_exit(struct signal_struct *sig) { }
+static inline void sched_autogroup_exit_task(struct task_struct *p) { }
#endif
extern int yield_to(struct task_struct *p, bool preempt);
diff --git a/kernel/exit.c b/kernel/exit.c
index 9d68c45ebbe3..3076f3089919 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -836,6 +836,7 @@ void __noreturn do_exit(long code)
*/
perf_event_exit_task(tsk);
+ sched_autogroup_exit_task(tsk);
cgroup_exit(tsk);
/*
diff --git a/kernel/sched/auto_group.c b/kernel/sched/auto_group.c
index ad2b19ad6ca0..f1c8fd566246 100644
--- a/kernel/sched/auto_group.c
+++ b/kernel/sched/auto_group.c
@@ -115,10 +115,26 @@ bool task_wants_autogroup(struct task_struct *p, struct task_group *tg)
* If we race with autogroup_move_group() the caller can use the old
* value of signal->autogroup but in this case sched_move_task() will
* be called again before autogroup_kref_put().
+ *
+ * However, there is no way sched_autogroup_exit_task() could tell us
+ * to avoid autogroup->tg, so we abuse PF_EXITING flag for this case.
*/
+ if (p->flags & PF_EXITING)
+ return false;
+
return true;
}
+void sched_autogroup_exit_task(struct task_struct *p)
+{
+ /*
+ * We are going to call exit_notify() and autogroup_move_group() can't
+ * see this thread after that: we can no longer use signal->autogroup.
+ * See the PF_EXITING check in task_wants_autogroup().
+ */
+ sched_move_task(p);
+}
+
static void
autogroup_move_group(struct task_struct *p, struct autogroup *ag)
{
@@ -142,6 +158,9 @@ autogroup_move_group(struct task_struct *p, struct autogroup *ag)
* In the latter case for_each_thread() can not miss a migrating thread,
* cpu_cgroup_attach() must not be possible after cgroup_exit() and it
* can't be removed from thread list, we hold ->siglock.
+ *
+ * If an exiting thread was already removed from thread list we rely on
+ * sched_autogroup_exit_task().
*/
for_each_thread(p, t)
sched_move_task(t);