Message ID | 20241026163707.2479526-1-shakeel.butt@linux.dev (mailing list archive) |
---|---|
State | New |
Headers | show |
Series | [v2] memcg: workingset: remove folio_memcg_rcu usage | expand |
On Sat, Oct 26, 2024 at 09:37:07AM GMT, Shakeel Butt wrote: > The function workingset_activation() is called from > folio_mark_accessed() with the guarantee that the given folio can not be > freed under us in workingset_activation(). In addition, the association > of the folio and its memcg can not be broken here because charge > migration is no more. There is no need to use folio_memcg_rcu. Simply > use folio_memcg_charged() because that is what this function cares > about. > > Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> > Suggested-by: Yu Zhao <yuzhao@google.com> > --- > Andrew, please put this patch after charge migration deprecation series. > > Changes since v1: > - Fix for mem_cgroup_disabled(). (Yu Zhao) > It seems like folio_memcg_charged() is not defined for CONFIG_MEMCG=n config option. The following stub should fix the build for such config. diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 89a1e9f10e1b..5502aa8e138e 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -1055,6 +1055,11 @@ static inline struct mem_cgroup *folio_memcg(struct folio *folio) return NULL; } +static inline bool folio_memcg_charged(struct folio *folio) +{ + return false; +} + static inline struct mem_cgroup *folio_memcg_check(struct folio *folio) { return NULL;
On Sat, 26 Oct 2024 23:55:14 -0700 Shakeel Butt <shakeel.butt@linux.dev> wrote: [...] It seems like folio_memcg_charged() is not defined for CONFIG_MEMCG=n > config option. The following stub should fix the build for such config. > > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 89a1e9f10e1b..5502aa8e138e 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -1055,6 +1055,11 @@ static inline struct mem_cgroup *folio_memcg(struct folio *folio) > return NULL; > } > > +static inline bool folio_memcg_charged(struct folio *folio) > +{ > + return false; > +} > + > static inline struct mem_cgroup *folio_memcg_check(struct folio *folio) > { > return NULL; Tested-by: SeongJae Park <sj@kernel.org> Thanks, SJ
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 932534291ca2..89a1e9f10e1b 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -443,35 +443,6 @@ static inline bool folio_memcg_charged(struct folio *folio) return __folio_memcg(folio) != NULL; } -/** - * folio_memcg_rcu - Locklessly get the memory cgroup associated with a folio. - * @folio: Pointer to the folio. - * - * This function assumes that the folio is known to have a - * proper memory cgroup pointer. It's not safe to call this function - * against some type of folios, e.g. slab folios or ex-slab folios. - * - * Return: A pointer to the memory cgroup associated with the folio, - * or NULL. - */ -static inline struct mem_cgroup *folio_memcg_rcu(struct folio *folio) -{ - unsigned long memcg_data = READ_ONCE(folio->memcg_data); - - VM_BUG_ON_FOLIO(folio_test_slab(folio), folio); - - if (memcg_data & MEMCG_DATA_KMEM) { - struct obj_cgroup *objcg; - - objcg = (void *)(memcg_data & ~OBJEXTS_FLAGS_MASK); - return obj_cgroup_memcg(objcg); - } - - WARN_ON_ONCE(!rcu_read_lock_held()); - - return (struct mem_cgroup *)(memcg_data & ~OBJEXTS_FLAGS_MASK); -} - /* * folio_memcg_check - Get the memory cgroup associated with a folio. * @folio: Pointer to the folio. @@ -1084,12 +1055,6 @@ static inline struct mem_cgroup *folio_memcg(struct folio *folio) return NULL; } -static inline struct mem_cgroup *folio_memcg_rcu(struct folio *folio) -{ - WARN_ON_ONCE(!rcu_read_lock_held()); - return NULL; -} - static inline struct mem_cgroup *folio_memcg_check(struct folio *folio) { return NULL; diff --git a/mm/workingset.c b/mm/workingset.c index 4b58ef535a17..a4705e196545 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -591,22 +591,12 @@ void workingset_refault(struct folio *folio, void *shadow) */ void workingset_activation(struct folio *folio) { - struct mem_cgroup *memcg; - - rcu_read_lock(); /* * Filter non-memcg pages here, e.g. unmap can call * mark_page_accessed() on VDSO pages. - * - * XXX: See workingset_refault() - this should return - * root_mem_cgroup even for !CONFIG_MEMCG. */ - memcg = folio_memcg_rcu(folio); - if (!mem_cgroup_disabled() && !memcg) - goto out; - workingset_age_nonresident(folio_lruvec(folio), folio_nr_pages(folio)); -out: - rcu_read_unlock(); + if (mem_cgroup_disabled() || folio_memcg_charged(folio)) + workingset_age_nonresident(folio_lruvec(folio), folio_nr_pages(folio)); } /*
The function workingset_activation() is called from folio_mark_accessed() with the guarantee that the given folio can not be freed under us in workingset_activation(). In addition, the association of the folio and its memcg can not be broken here because charge migration is no more. There is no need to use folio_memcg_rcu. Simply use folio_memcg_charged() because that is what this function cares about. Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Suggested-by: Yu Zhao <yuzhao@google.com> --- Andrew, please put this patch after charge migration deprecation series. Changes since v1: - Fix for mem_cgroup_disabled(). (Yu Zhao) include/linux/memcontrol.h | 35 ----------------------------------- mm/workingset.c | 14 ++------------ 2 files changed, 2 insertions(+), 47 deletions(-)