On Wednesday, July 27, 2011, Oliver Neukum wrote:
> From ee5849f0bc39d554ef91747ff80c307ac3e05cdd Mon Sep 17 00:00:00 2001
> From: Oliver Neukum <oliver@xxxxxxxxxx>
> Date: Wed, 27 Jul 2011 12:27:00 +0200
> Subject: [PATCH] Unfreeze tasks after an oops in the freezer
>
> If an oops kills the task suspending or snapshotting
> is system, the system is dead because the action is
> never completed and the tasks never thawed.
>
> Signed-off-by: Oliver Neukum <oneukum@xxxxxxx>
> ---
> include/linux/freezer.h | 2 ++
> kernel/panic.c | 8 ++++++++
> kernel/power/process.c | 11 +++++++++++
> 3 files changed, 21 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/freezer.h b/include/linux/freezer.h
> index 1effc8b..ab0168a 100644
> --- a/include/linux/freezer.h
> +++ b/include/linux/freezer.h
> @@ -50,6 +50,7 @@ extern int thaw_process(struct task_struct *p);
> extern void refrigerator(void);
> extern int freeze_processes(void);
> extern void thaw_processes(void);
> +extern void thaw_in_oops(void);
>
> static inline int try_to_freeze(void)
> {
> @@ -181,6 +182,7 @@ static inline void freezer_count(void) {}
> static inline int freezer_should_skip(struct task_struct *p) { return 0; }
> static inline void set_freezable(void) {}
> static inline void set_freezable_with_signal(void) {}
> +static inline void thaw_in_oops(void) {}
>
> #define wait_event_freezable(wq, condition) \
> wait_event_interruptible(wq, condition)
> diff --git a/kernel/panic.c b/kernel/panic.c
> index 6923167..ccdd834 100644
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -23,6 +23,7 @@
> #include <linux/init.h>
> #include <linux/nmi.h>
> #include <linux/dmi.h>
> +#include <linux/freezer.h>
>
> #define PANIC_TIMER_STEP 100
> #define PANIC_BLINK_SPD 18
> @@ -355,6 +356,13 @@ void oops_exit(void)
> do_oops_enter_exit();
> print_oops_end_marker();
> kmsg_dump(KMSG_DUMP_OOPS);
> + /*
> + * if we oops while tasks are frozen, the system
> + * will stop dead because the task that would thaw it
> + * has been killed. So the system must be explicitly
> + * thawed here.
> + */
> + thaw_in_oops();
> }
>
> #ifdef WANT_WARN_ON_SLOWPATH
> diff --git a/kernel/power/process.c b/kernel/power/process.c
> index 0cf3a27..c03e88b 100644
> --- a/kernel/power/process.c
> +++ b/kernel/power/process.c
> @@ -22,6 +22,9 @@
> */
> #define TIMEOUT (20 * HZ)
>
> +/* in case we oops while processes are frozen */
> +static bool tasks_frozen = false;
> +
> static inline int freezable(struct task_struct * p)
> {
> if ((p == current) ||
> @@ -131,6 +134,7 @@ static int try_to_freeze_tasks(bool sig_only)
> elapsed_csecs % 100);
> }
>
> + tasks_frozen = (todo == 0);
I'd prefer it to be set by freeze_processes(), when oom_killer_disable()
is called.
> return todo ? -EBUSY : 0;
> }
>
> @@ -189,7 +193,14 @@ void thaw_processes(void)
> thaw_workqueues();
> thaw_tasks(true);
> thaw_tasks(false);
> + tasks_frozen = false;
> schedule();
> printk("done.\n");
> }
>
> +void thaw_in_oops(void)
> +{
> + if (tasks_frozen)
> + thaw_processes();
> +}
> +
Thanks,
Rafael
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