On Fri 18-04-14 21:12:59, Oleg Nesterov wrote:
> On 04/18, Oleg Nesterov wrote:
> >
> > OTOH, mm->owner is used by mm/memcontrol.c, so perhaps the prefix is fine?
> >
> > I do not even understand why do we have CONFIG_MM_OWNER, perhaps it should
> > die?
>
> Seriously what do you think about the patch below? Afaics CONFIG_MM_OWNER
> is pointless.
Yes, I do not see any reason for a separate config when it has a single
user which cannot work without it. So feel free to add my
Acked-by: Michal Hocko <mho...@suse.cz>
to the patch with your s-o-b and a simple changelog explaining there the
config option didn't have any user outside of MEMCG which cannot work
without it.
> And I just noticed start_kernel()->mm_init_owner(). It looks simply wrong
> even if this is harmless, or I missed something?
>
> Could you review 1/1 as well?
>
> Oleg.
> ---
>
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index 8967e20..de16272 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -406,7 +406,7 @@ struct mm_struct {
> spinlock_t ioctx_lock;
> struct kioctx_table __rcu *ioctx_table;
> #endif
> -#ifdef CONFIG_MM_OWNER
> +#ifdef CONFIG_MEMCG
> /*
> * "owner" points to a task that is regarded as the canonical
> * user/owner of this mm. All of the following must be true in
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 82fe3da..570a325 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -2947,7 +2947,7 @@ static inline void inc_syscw(struct task_struct *tsk)
> #define TASK_SIZE_OF(tsk) TASK_SIZE
> #endif
>
> -#ifdef CONFIG_MM_OWNER
> +#ifdef CONFIG_MEMCG
> extern void mm_update_next_owner(struct mm_struct *mm);
> extern void mm_init_owner(struct mm_struct *mm, struct task_struct *p);
> #else
> @@ -2958,7 +2958,7 @@ static inline void mm_update_next_owner(struct
> mm_struct *mm)
> static inline void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
> {
> }
> -#endif /* CONFIG_MM_OWNER */
> +#endif /* CONFIG_MEMCG */
>
> static inline unsigned long task_rlimit(const struct task_struct *tsk,
> unsigned int limit)
> diff --git a/init/Kconfig b/init/Kconfig
> index 765018c..143119e 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -933,7 +933,6 @@ config RESOURCE_COUNTERS
> config MEMCG
> bool "Memory Resource Controller for Control Groups"
> depends on RESOURCE_COUNTERS
> - select MM_OWNER
> select EVENTFD
> help
> Provides a memory resource controller that manages both anonymous
> @@ -951,9 +950,6 @@ config MEMCG
> disable memory resource controller and you can avoid overheads.
> (and lose benefits of memory resource controller)
>
> - This config option also selects MM_OWNER config option, which
> - could in turn add some fork/exit overhead.
> -
> config MEMCG_SWAP
> bool "Memory Resource Controller Swap Extension"
> depends on MEMCG && SWAP
> @@ -1173,9 +1169,6 @@ config SCHED_AUTOGROUP
> desktop applications. Task group autogeneration is currently based
> upon task session.
>
> -config MM_OWNER
> - bool
> -
> config SYSFS_DEPRECATED
> bool "Enable deprecated sysfs features to support old userspace tools"
> depends on SYSFS
> diff --git a/kernel/exit.c b/kernel/exit.c
> index 429659c..e5c4668 100644
> --- a/kernel/exit.c
> +++ b/kernel/exit.c
> @@ -313,7 +313,7 @@ kill_orphaned_pgrp(struct task_struct *tsk, struct
> task_struct *parent)
> }
> }
>
> -#ifdef CONFIG_MM_OWNER
> +#ifdef CONFIG_MEMCG
> /*
> * A task is exiting. If it owned this mm, find a new owner for the mm.
> */
> @@ -399,7 +399,7 @@ assign_new_owner:
> task_unlock(c);
> put_task_struct(c);
> }
> -#endif /* CONFIG_MM_OWNER */
> +#endif /* CONFIG_MEMCG */
>
> /*
> * Turn us into a lazy TLB process if we
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 54a8d26..ed75cf5 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -1099,12 +1099,12 @@ static void rt_mutex_init_task(struct task_struct *p)
> #endif
> }
>
> -#ifdef CONFIG_MM_OWNER
> +#ifdef CONFIG_MEMCG
> void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
> {
> mm->owner = p;
> }
> -#endif /* CONFIG_MM_OWNER */
> +#endif /* CONFIG_MEMCG */
>
> /*
> * Initialize POSIX timer handling for a single task.
>
--
Michal Hocko
SUSE Labs
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