Add pgalloc_tag_copy() to transfer the codetag from the old folio to the new one during migration. This makes original allocation sites persist cross migration rather than lump into the get_new_folio callbacks passed into migrate_pages(), e.g., compaction_alloc():

# echo 1 >/proc/sys/vm/compact_memory # grep compaction_alloc /proc/allocinfo

Before this patch: 132968448 32463 mm/compaction.c:1880 func:compaction_alloc

After this patch: 0 0 mm/compaction.c:1880 func:compaction_alloc

Fixes: dcfe378c81f7 ("lib: introduce support for page allocation tagging") Signed-off-by: Yu Zhao yuzhao@google.com Acked-by: Suren Baghdasaryan surenb@google.com Cc: stable@vger.kernel.org --- include/linux/alloc_tag.h | 24 ++++++++++-------------- include/linux/mm.h | 27 +++++++++++++++++++++++++++ mm/migrate.c | 1 + 3 files changed, 38 insertions(+), 14 deletions(-)

diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h index 896491d9ebe8..1f0a9ff23a2c 100644 --- a/include/linux/alloc_tag.h +++ b/include/linux/alloc_tag.h @@ -137,7 +137,16 @@ static inline void alloc_tag_sub_check(union codetag_ref *ref) {} /* Caller should verify both ref and tag to be valid */ static inline void __alloc_tag_ref_set(union codetag_ref *ref, struct alloc_tag *tag) { + alloc_tag_add_check(ref, tag); + if (!ref || !tag) + return; + ref->ct = &tag->ct; +} + +static inline void alloc_tag_ref_set(union codetag_ref *ref, struct alloc_tag *tag) +{ + __alloc_tag_ref_set(ref, tag); /* * We need in increment the call counter every time we have a new * allocation or when we split a large allocation into smaller ones. @@ -147,22 +156,9 @@ static inline void __alloc_tag_ref_set(union codetag_ref *ref, struct alloc_tag this_cpu_inc(tag->counters->calls); }

-static inline void alloc_tag_ref_set(union codetag_ref *ref, struct alloc_tag *tag) -{ - alloc_tag_add_check(ref, tag); - if (!ref || !tag) - return; - - __alloc_tag_ref_set(ref, tag); -} - static inline void alloc_tag_add(union codetag_ref *ref, struct alloc_tag *tag, size_t bytes) { - alloc_tag_add_check(ref, tag); - if (!ref || !tag) - return; - - __alloc_tag_ref_set(ref, tag); + alloc_tag_ref_set(ref, tag); this_cpu_add(tag->counters->bytes, bytes); }

diff --git a/include/linux/mm.h b/include/linux/mm.h index a07e93adb8ad..d750be768121 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -4161,10 +4161,37 @@ static inline void pgalloc_tag_split(struct folio *folio, int old_order, int new } } } + +static inline void pgalloc_tag_copy(struct folio *new, struct folio *old) +{ + struct alloc_tag *tag; + union codetag_ref *ref; + + tag = pgalloc_tag_get(&old->page); + if (!tag) + return; + + ref = get_page_tag_ref(&new->page); + if (!ref) + return; + + /* Clear the old ref to the original allocation tag. */ + clear_page_tag_ref(&old->page); + /* Decrement the counters of the tag on get_new_folio. */ + alloc_tag_sub(ref, folio_nr_pages(new)); + + __alloc_tag_ref_set(ref, tag); + + put_page_tag_ref(ref); +} #else /* !CONFIG_MEM_ALLOC_PROFILING */ static inline void pgalloc_tag_split(struct folio *folio, int old_order, int new_order) { } + +static inline void pgalloc_tag_copy(struct folio *new, struct folio *old) +{ +} #endif /* CONFIG_MEM_ALLOC_PROFILING */

#endif /* _LINUX_MM_H */ diff --git a/mm/migrate.c b/mm/migrate.c index 0f6b78fd73aa..dfdb3a136bf8 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -743,6 +743,7 @@ void folio_migrate_flags(struct folio *newfolio, struct folio *folio) folio_set_readahead(newfolio);

folio_copy_owner(newfolio, folio); + pgalloc_tag_copy(newfolio, folio);

mem_cgroup_migrate(folio, newfolio); }