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

[Suren Baghdasaryan <surenb@google.com>]

On Tue, Sep 9, 2025 at 2:15 AM Michal Hocko <mhocko@suse.com> wrote:
>
> 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@

Do you suggest renaming thaw_oom_process() into thaw_processes()
(s/thaw_oom_process/thaw_processes)? If so, I don't think that's a
better name considering the function sets TIF_MEMDIE flag. From that
perspective less generic thaw_oom_process() seems appropriate, no?

>
> 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