freezer: remove racy clear_freeze_flag() and set PF_NOFREEZE on dead tasks
clear_freeze_flag() in exit_mm() is racy. Freezing can start
afterwards. Remove it. Skipping freezer for exiting task will be
properly implemented later.
Also, freezable() was testing exit_state directly to make system
freezer ignore dead tasks. Let the exiting task set PF_NOFREEZE after
entering TASK_DEAD instead.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
diff --git a/kernel/power/process.c b/kernel/power/process.c
index fe27872..23822dc 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -25,8 +25,7 @@
static inline int freezable(struct task_struct * p)
{
if ((p == current) ||
- (p->flags & PF_NOFREEZE) ||
- (p->exit_state != 0))
+ (p->flags & PF_NOFREEZE))
return 0;
return 1;
}