Messages in this thread | | | From | Shakeel Butt <> | Date | Wed, 16 Sep 2020 18:12:37 -0700 | Subject | Re: [PATCH rfc 3/5] mm: memcontrol/slab: use helpers to access slab page's memcg_data |
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On Thu, Sep 10, 2020 at 1:27 PM Roman Gushchin <guro@fb.com> wrote: > > To gather all direct accesses to struct page's memcg_data field > in one place, let's introduce 4 new helper functions to use in > the slab accounting code: > struct obj_cgroup **page_obj_cgroups(struct page *page); > struct obj_cgroup **page_obj_cgroups_check(struct page *page); > bool set_page_obj_cgroups(struct page *page, struct obj_cgroup **objcgs); > void clear_page_obj_cgroups(struct page *page); > > They are similar to the corresponding API for generic pages, except > that the setter can return false, indicating that the value has been > already set from a different thread. > > Signed-off-by: Roman Gushchin <guro@fb.com>
Nit below.
Reviewed-by: Shakeel Butt <shakeelb@google.com>
> --- > include/linux/memcontrol.h | 48 ++++++++++++++++++++++++++++++++++++++ > mm/memcontrol.c | 4 ++-- > mm/slab.h | 27 +++------------------ > 3 files changed, 53 insertions(+), 26 deletions(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 0997220c84ce..48d4c2c1ce81 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -375,6 +375,54 @@ static inline void clear_page_mem_cgroup(struct page *page) > page->memcg_data = 0; > } >
I think adding comments on these functions would be helpful.
> +#ifdef CONFIG_MEMCG_KMEM > +static inline struct obj_cgroup **page_obj_cgroups(struct page *page) > +{ > + return (struct obj_cgroup **)(page->memcg_data & ~0x1UL); > +} > + > +static inline struct obj_cgroup **page_obj_cgroups_check(struct page *page) > +{ > + unsigned long memcg_data = page->memcg_data; > + > + if (memcg_data && (memcg_data & 0x1UL)) > + return (struct obj_cgroup **)memcg_data; > + > + return NULL; > +} > + > +static inline bool set_page_obj_cgroups(struct page *page, > + struct obj_cgroup **objcgs) > +{ > + return !cmpxchg(&page->memcg_data, 0, (unsigned long)objcgs | 0x1UL); > +} > + > +static inline void clear_page_obj_cgroups(struct page *page) > +{ > + page->memcg_data = 0; > +}
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