diff --git a/include/linux/freezer.h b/include/linux/freezer.h
index 2d38b1a7466251bded8a45d01d41cca577cf40b1..c8e02de737f6b07a3443d53362aee0d3bc507087 100644
--- a/include/linux/freezer.h
+++ b/include/linux/freezer.h
@@ -25,7 +25,7 @@ static inline int freezing(struct task_struct *p)
/*
* Request that a process be frozen
*/
-static inline void freeze(struct task_struct *p)
+static inline void set_freeze_flag(struct task_struct *p)
{
set_tsk_thread_flag(p, TIF_FREEZE);
}
@@ -33,7 +33,7 @@ static inline void freeze(struct task_struct *p)
/*
* Sometimes we may need to cancel the previous 'freeze' request
*/
-static inline void do_not_freeze(struct task_struct *p)
+static inline void clear_freeze_flag(struct task_struct *p)
{
clear_tsk_thread_flag(p, TIF_FREEZE);
}
@@ -56,7 +56,7 @@ static inline int thaw_process(struct task_struct *p)
wake_up_process(p);
return 1;
}
- clear_tsk_thread_flag(p, TIF_FREEZE);
+ clear_freeze_flag(p);
task_unlock(p);
return 0;
}
@@ -129,7 +129,8 @@ static inline void set_freezable(void)
#else
static inline int frozen(struct task_struct *p) { return 0; }
static inline int freezing(struct task_struct *p) { return 0; }
-static inline void freeze(struct task_struct *p) { BUG(); }
+static inline void set_freeze_flag(struct task_struct *p) {}
+static inline void clear_freeze_flag(struct task_struct *p) {}
static inline int thaw_process(struct task_struct *p) { return 1; }
static inline void refrigerator(void) {}
diff --git a/kernel/exit.c b/kernel/exit.c
index e8af8d0c2483232248ba163dc0e9eb03ad6ed504..464c2b172f07477ca27a453edcf93fb6eeebe1c6 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -45,6 +45,7 @@
#include <linux/resource.h>
#include <linux/blkdev.h>
#include <linux/task_io_accounting_ops.h>
+#include <linux/freezer.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>
@@ -594,6 +595,8 @@ 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);
mmput(mm);
}
diff --git a/kernel/power/process.c b/kernel/power/process.c
index b850173e7561058e768675f3a11d04087a185999..e1bcdedd1464046204e4347489803d990547cc0c 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -40,7 +40,7 @@ static inline void frozen_process(void)
current->flags |= PF_FROZEN;
wmb();
}
- clear_tsk_thread_flag(current, TIF_FREEZE);
+ clear_freeze_flag(current);
}
/* Refrigerator is place where frozen processes are stored :-). */
@@ -75,17 +75,16 @@ void refrigerator(void)
current->state = save;
}
-static inline void freeze_process(struct task_struct *p)
+static void freeze_task(struct task_struct *p)
{
unsigned long flags;
if (!freezing(p)) {
rmb();
if (!frozen(p)) {
+ set_freeze_flag(p);
if (p->state == TASK_STOPPED)
force_sig_specific(SIGSTOP, p);
-
- freeze(p);
spin_lock_irqsave(&p->sighand->siglock, flags);
signal_wake_up(p, p->state == TASK_STOPPED);
spin_unlock_irqrestore(&p->sighand->siglock, flags);
@@ -99,18 +98,13 @@ static void cancel_freezing(struct task_struct *p)
if (freezing(p)) {
pr_debug(" clean up: %s\n", p->comm);
- do_not_freeze(p);
+ clear_freeze_flag(p);
spin_lock_irqsave(&p->sighand->siglock, flags);
recalc_sigpending_and_wake(p);
spin_unlock_irqrestore(&p->sighand->siglock, flags);
}
}
-static inline int is_user_space(struct task_struct *p)
-{
- return p->mm && !(p->flags & PF_BORROWED_MM);
-}
-
static unsigned int try_to_freeze_tasks(int freeze_user_space)
{
struct task_struct *g, *p;
@@ -122,20 +116,34 @@ static unsigned int try_to_freeze_tasks(int freeze_user_space)
todo = 0;
read_lock(&tasklist_lock);
do_each_thread(g, p) {
- if (!freezeable(p))
- continue;
-
- if (frozen(p))
+ if (frozen(p) || !freezeable(p))
continue;
- if (p->state == TASK_TRACED && frozen(p->parent)) {
- cancel_freezing(p);
- continue;
+ if (freeze_user_space) {
+ if (p->state == TASK_TRACED &&
+ frozen(p->parent)) {
+ cancel_freezing(p);
+ continue;
+ }
+ /*
+ * Kernel threads should not have TIF_FREEZE set
+ * at this point, so we must ensure that either
+ * p->mm is not NULL *and* PF_BORROWED_MM is
+ * unset, or TIF_FRREZE is left unset.
+ * The task_lock() is necessary to prevent races
+ * with exit_mm() or use_mm()/unuse_mm() from
+ * occuring.
+ */
+ task_lock(p);
+ if (!p->mm || (p->flags & PF_BORROWED_MM)) {
+ task_unlock(p);
+ continue;
+ }
+ freeze_task(p);
+ task_unlock(p);
+ } else {
+ freeze_task(p);
}
- if (freeze_user_space && !is_user_space(p))
- continue;
-
- freeze_process(p);
if (!freezer_should_skip(p))
todo++;
} while_each_thread(g, p);
@@ -152,22 +160,16 @@ static unsigned int try_to_freeze_tasks(int freeze_user_space)
* but it cleans up leftover PF_FREEZE requests.
*/
printk("\n");
- printk(KERN_ERR "Stopping %s timed out after %d seconds "
+ printk(KERN_ERR "Freezing of %s timed out after %d seconds "
"(%d tasks refusing to freeze):\n",
- freeze_user_space ? "user space processes" :
- "kernel threads",
+ freeze_user_space ? "user space " : "tasks ",
TIMEOUT / HZ, todo);
show_state();
read_lock(&tasklist_lock);
do_each_thread(g, p) {
- if (freeze_user_space && !is_user_space(p))
- continue;
-
task_lock(p);
- if (freezeable(p) && !frozen(p) &&
- !freezer_should_skip(p))
+ if (freezing(p) && !freezer_should_skip(p))
printk(KERN_ERR " %s\n", p->comm);
-
cancel_freezing(p);
task_unlock(p);
} while_each_thread(g, p);
@@ -211,7 +213,7 @@ static void thaw_tasks(int thaw_user_space)
if (!freezeable(p))
continue;
- if (is_user_space(p) == !thaw_user_space)
+ if (!p->mm == thaw_user_space)
continue;
thaw_process(p);