Message ID | 20240925030225.236143-1-zhaoyang.huang@unisoc.com (mailing list archive) |
---|---|
State | New |
Headers | show |
Series | mm: migrate LRU_REFS_MASK bits in folio_migrate_flags | expand |
On Wed, 25 Sep 2024 11:02:25 +0800 "zhaoyang.huang" <zhaoyang.huang@unisoc.com> wrote: > From: Zhaoyang Huang <zhaoyang.huang@unisoc.com> > > Bits of LRU_REFS_MASK are not inherited during migration which lead to > new_folio start from tier0. Fix this by migrate the bits domain. I'm having trouble understanding this, sorry. Please more fully describe the runtime effects of this flaw. > --- a/include/linux/mm_inline.h > +++ b/include/linux/mm_inline.h > @@ -291,6 +291,12 @@ static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, > return true; > } > > +static inline void folio_migrate_refs(struct folio *new_folio, struct folio *folio) > +{ > + unsigned long refs = READ_ONCE(folio->flags) & LRU_REFS_MASK; > + > + set_mask_bits(&new_folio->flags, LRU_REFS_MASK, refs); > +} > #else /* !CONFIG_LRU_GEN */ > > static inline bool lru_gen_enabled(void) > @@ -313,6 +319,8 @@ static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, > return false; > } > > +static inline void folio_migrate_refs(struct folio *new_folio, struct folio *folio) > +{} > #endif /* CONFIG_LRU_GEN */ > > static __always_inline > diff --git a/mm/migrate.c b/mm/migrate.c > index 923ea80ba744..60c97e235ae7 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -618,6 +618,7 @@ void folio_migrate_flags(struct folio *newfolio, struct folio *folio) > if (folio_test_idle(folio)) > folio_set_idle(newfolio); > > + folio_migrate_refs(newfolio, folio); > /* > * Copy NUMA information to the new page, to prevent over-eager > * future migrations of this same page. > -- > 2.25.1
On Wed, Sep 25, 2024 at 5:42 PM Andrew Morton <akpm@linux-foundation.org> wrote: > > On Wed, 25 Sep 2024 11:02:25 +0800 "zhaoyang.huang" <zhaoyang.huang@unisoc.com> wrote: > > > From: Zhaoyang Huang <zhaoyang.huang@unisoc.com> > > > > Bits of LRU_REFS_MASK are not inherited during migration which lead to > > new_folio start from tier0. Fix this by migrate the bits domain. > > I'm having trouble understanding this, sorry. Please more fully > describe the runtime effects of this flaw. Sorry for bringing confusion. According to my understanding, MGLRU records how many times that vfs access this page in a range of bits domain(LRU_REFS_MASK) in folio->flags which are not being migrated to new_folios so far. This commit would like to do so to have the new_folio inherit these bits from the old folio. Is it right and worthy to do? > > > --- a/include/linux/mm_inline.h > > +++ b/include/linux/mm_inline.h > > @@ -291,6 +291,12 @@ static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, > > return true; > > } > > > > +static inline void folio_migrate_refs(struct folio *new_folio, struct folio *folio) > > +{ > > + unsigned long refs = READ_ONCE(folio->flags) & LRU_REFS_MASK; > > + > > + set_mask_bits(&new_folio->flags, LRU_REFS_MASK, refs); > > +} > > #else /* !CONFIG_LRU_GEN */ > > > > static inline bool lru_gen_enabled(void) > > @@ -313,6 +319,8 @@ static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, > > return false; > > } > > > > +static inline void folio_migrate_refs(struct folio *new_folio, struct folio *folio) > > +{} > > #endif /* CONFIG_LRU_GEN */ > > > > static __always_inline > > diff --git a/mm/migrate.c b/mm/migrate.c > > index 923ea80ba744..60c97e235ae7 100644 > > --- a/mm/migrate.c > > +++ b/mm/migrate.c > > @@ -618,6 +618,7 @@ void folio_migrate_flags(struct folio *newfolio, struct folio *folio) > > if (folio_test_idle(folio)) > > folio_set_idle(newfolio); > > > > + folio_migrate_refs(newfolio, folio); > > /* > > * Copy NUMA information to the new page, to prevent over-eager > > * future migrations of this same page. > > -- > > 2.25.1
diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index f4fe593c1400..ecf07a2a8201 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -291,6 +291,12 @@ static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, return true; } +static inline void folio_migrate_refs(struct folio *new_folio, struct folio *folio) +{ + unsigned long refs = READ_ONCE(folio->flags) & LRU_REFS_MASK; + + set_mask_bits(&new_folio->flags, LRU_REFS_MASK, refs); +} #else /* !CONFIG_LRU_GEN */ static inline bool lru_gen_enabled(void) @@ -313,6 +319,8 @@ static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, return false; } +static inline void folio_migrate_refs(struct folio *new_folio, struct folio *folio) +{} #endif /* CONFIG_LRU_GEN */ static __always_inline diff --git a/mm/migrate.c b/mm/migrate.c index 923ea80ba744..60c97e235ae7 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -618,6 +618,7 @@ void folio_migrate_flags(struct folio *newfolio, struct folio *folio) if (folio_test_idle(folio)) folio_set_idle(newfolio); + folio_migrate_refs(newfolio, folio); /* * Copy NUMA information to the new page, to prevent over-eager * future migrations of this same page.