Re: [PATCH v8 1/3] mm/oom_kill: Introduce thaw_oom_process() for thawing OOM victims

[Michal Hocko <mhocko@suse.com>]

On Tue 09-09-25 17:06:57, zhongjinji wrote:
> OOM killer is a mechanism that selects and kills processes when the system
> runs out of memory to reclaim resources and keep the system stable.
> However, the oom victim cannot terminate on its own when it is frozen,
> because __thaw_task() only thaws one thread of the victim, while
> the other threads remain in the frozen state.
> 
> Since __thaw_task did not fully thaw the OOM victim for self-termination,
> introduce thaw_oom_process() to properly thaw OOM victims.

You will need s@thaw_oom_process@thaw_processes@

I would also add the caller in this patch.

> Signed-off-by: zhongjinji <zhongjinji@honor.com>

Other than that looks good to me. With the above fixed feel free to add
Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  include/linux/freezer.h |  2 ++
>  kernel/freezer.c        | 19 +++++++++++++++++++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/include/linux/freezer.h b/include/linux/freezer.h
> index b303472255be..19a4b57950cd 100644
> --- a/include/linux/freezer.h
> +++ b/include/linux/freezer.h
> @@ -47,6 +47,7 @@ extern int freeze_processes(void);
>  extern int freeze_kernel_threads(void);
>  extern void thaw_processes(void);
>  extern void thaw_kernel_threads(void);
> +extern void thaw_oom_process(struct task_struct *p);
>  
>  static inline bool try_to_freeze(void)
>  {
> @@ -80,6 +81,7 @@ static inline int freeze_processes(void) { return -ENOSYS; }
>  static inline int freeze_kernel_threads(void) { return -ENOSYS; }
>  static inline void thaw_processes(void) {}
>  static inline void thaw_kernel_threads(void) {}
> +static inline void thaw_oom_process(struct task_struct *p) {}
>  
>  static inline bool try_to_freeze(void) { return false; }
>  
> diff --git a/kernel/freezer.c b/kernel/freezer.c
> index 6a96149aede9..17970e0be8a7 100644
> --- a/kernel/freezer.c
> +++ b/kernel/freezer.c
> @@ -206,6 +206,25 @@ void __thaw_task(struct task_struct *p)
>  		wake_up_state(p, TASK_FROZEN);
>  }
>  
> +/*
> + * thaw_oom_process - thaw the OOM victim process
> + * @p: process to be thawed
> + *
> + * Sets TIF_MEMDIE for all threads in the process group and thaws them.
> + * Threads with TIF_MEMDIE are ignored by the freezer.
> + */
> +void thaw_oom_process(struct task_struct *p)
> +{
> +	struct task_struct *t;
> +
> +	rcu_read_lock();
> +	for_each_thread(p, t) {
> +		set_tsk_thread_flag(t, TIF_MEMDIE);
> +		__thaw_task(t);
> +	}
> +	rcu_read_unlock();
> +}
> +
>  /**
>   * set_freezable - make %current freezable
>   *
> -- 
> 2.17.1

-- 
Michal Hocko
SUSE Labs