From a585042f7b933539a0b6bc63650c2d49ffb2e55d Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 21 Nov 2011 12:32:23 -0800 Subject: [PATCH] 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 Cc: Oleg Nesterov --- kernel/exit.c | 3 +-- kernel/power/process.c | 3 +-- 2 files changed, 2 insertions(+), 4 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index d0b7d988f873..95a4141d07e7 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -679,8 +679,6 @@ static void exit_mm(struct task_struct * tsk) tsk->mm = NULL; up_read(&mm->mmap_sem); enter_lazy_tlb(mm, current); - /* We don't want this task to be frozen prematurely */ - clear_freeze_flag(tsk); task_unlock(tsk); mm_update_next_owner(mm); mmput(mm); @@ -1040,6 +1038,7 @@ NORET_TYPE void do_exit(long code) exit_rcu(); /* causes final put_task_struct in finish_task_switch(). */ tsk->state = TASK_DEAD; + tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */ schedule(); BUG(); /* Avoid "noreturn function does return". */ diff --git a/kernel/power/process.c b/kernel/power/process.c index fe2787207f00..23822dc14b6c 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; } -- 2.34.1