Re: [PATCH v2 19/47] mm: thp: dynamically allocate the thp-related shrinkers

[Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>]

On 2023/7/26 15:10, Muchun Song wrote:
> On 2023/7/24 17:43, Qi Zheng wrote:
> > Use new APIs to dynamically allocate the thp-zero and thp-deferred_split
> > shrinkers.
> >
> > Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
> > ---
> >   mm/huge_memory.c | 69 +++++++++++++++++++++++++++++++-----------------
> >   1 file changed, 45 insertions(+), 24 deletions(-)
> >
> > diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> > index 8c94b34024a2..4db5a1834d81 100644
> > --- a/mm/huge_memory.c
> > +++ b/mm/huge_memory.c
> > @@ -65,7 +65,11 @@ unsigned long transparent_hugepage_flags 
> > __read_mostly =
> >       (1<<TRANSPARENT_HUGEPAGE_DEFRAG_KHUGEPAGED_FLAG)|
> >       (1<<TRANSPARENT_HUGEPAGE_USE_ZERO_PAGE_FLAG);
> > -static struct shrinker deferred_split_shrinker;
> > +static struct shrinker *deferred_split_shrinker;
> > +static unsigned long deferred_split_count(struct shrinker *shrink,
> > +                      struct shrink_control *sc);
> > +static unsigned long deferred_split_scan(struct shrinker *shrink,
> > +                     struct shrink_control *sc);
> >   static atomic_t huge_zero_refcount;
> >   struct page *huge_zero_page __read_mostly;
> > @@ -229,11 +233,7 @@ static unsigned long 
> > shrink_huge_zero_page_scan(struct shrinker *shrink,
> >       return 0;
> >   }
> > -static struct shrinker huge_zero_page_shrinker = {
> > -    .count_objects = shrink_huge_zero_page_count,
> > -    .scan_objects = shrink_huge_zero_page_scan,
> > -    .seeks = DEFAULT_SEEKS,
> > -};
> > +static struct shrinker *huge_zero_page_shrinker;
> Same as patch #17.
OK, will do.

> >   #ifdef CONFIG_SYSFS
> >   static ssize_t enabled_show(struct kobject *kobj,
> > @@ -454,6 +454,40 @@ static inline void hugepage_exit_sysfs(struct 
> > kobject *hugepage_kobj)
> >   }
> >   #endif /* CONFIG_SYSFS */
> > +static int thp_shrinker_init(void)
> Better to declare it as __init.
Will do.

> > +{
> > +    huge_zero_page_shrinker = shrinker_alloc(0, "thp-zero");
> > +    if (!huge_zero_page_shrinker)
> > +        return -ENOMEM;
> > +
> > +    deferred_split_shrinker = shrinker_alloc(SHRINKER_NUMA_AWARE |
> > +                         SHRINKER_MEMCG_AWARE |
> > +                         SHRINKER_NONSLAB,
> > +                         "thp-deferred_split");
> > +    if (!deferred_split_shrinker) {
> > +        shrinker_free_non_registered(huge_zero_page_shrinker);
> > +        return -ENOMEM;
> > +    }
> > +
> > +    huge_zero_page_shrinker->count_objects = 
> > shrink_huge_zero_page_count;
> > +    huge_zero_page_shrinker->scan_objects = shrink_huge_zero_page_scan;
> > +    huge_zero_page_shrinker->seeks = DEFAULT_SEEKS;
> > +    shrinker_register(huge_zero_page_shrinker);
> > +
> > +    deferred_split_shrinker->count_objects = deferred_split_count;
> > +    deferred_split_shrinker->scan_objects = deferred_split_scan;
> > +    deferred_split_shrinker->seeks = DEFAULT_SEEKS;
> > +    shrinker_register(deferred_split_shrinker);
> > +
> > +    return 0;
> > +}
> > +
> > +static void thp_shrinker_exit(void)
> Same as here.
Will do.

> > +{
> > +    shrinker_unregister(huge_zero_page_shrinker);
> > +    shrinker_unregister(deferred_split_shrinker);
> > +}
> > +
> >   static int __init hugepage_init(void)
> >   {
> >       int err;
> > @@ -482,12 +516,9 @@ static int __init hugepage_init(void)
> >       if (err)
> >           goto err_slab;
> > -    err = register_shrinker(&huge_zero_page_shrinker, "thp-zero");
> > -    if (err)
> > -        goto err_hzp_shrinker;
> > -    err = register_shrinker(&deferred_split_shrinker, 
> > "thp-deferred_split");
> > +    err = thp_shrinker_init();
> >       if (err)
> > -        goto err_split_shrinker;
> > +        goto err_shrinker;
> >       /*
> >        * By default disable transparent hugepages on smaller systems,
> > @@ -505,10 +536,8 @@ static int __init hugepage_init(void)
> >       return 0;
> >   err_khugepaged:
> > -    unregister_shrinker(&deferred_split_shrinker);
> > -err_split_shrinker:
> > -    unregister_shrinker(&huge_zero_page_shrinker);
> > -err_hzp_shrinker:
> > +    thp_shrinker_exit();
> > +err_shrinker:
> >       khugepaged_destroy();
> >   err_slab:
> >       hugepage_exit_sysfs(hugepage_kobj);
> > @@ -2851,7 +2880,7 @@ void deferred_split_folio(struct folio *folio)
> >   #ifdef CONFIG_MEMCG
> >           if (memcg)
> >               set_shrinker_bit(memcg, folio_nid(folio),
> > -                     deferred_split_shrinker.id);
> > +                     deferred_split_shrinker->id);
> >   #endif
> >       }
> >       spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
> > @@ -2925,14 +2954,6 @@ static unsigned long deferred_split_scan(struct 
> > shrinker *shrink,
> >       return split;
> >   }
> > -static struct shrinker deferred_split_shrinker = {
> > -    .count_objects = deferred_split_count,
> > -    .scan_objects = deferred_split_scan,
> > -    .seeks = DEFAULT_SEEKS,
> > -    .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE |
> > -         SHRINKER_NONSLAB,
> > -};
> > -
> >   #ifdef CONFIG_DEBUG_FS
> >   static void split_huge_pages_all(void)
> >   {