summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorDavid Wang <00107082@163.com>2024-11-29 10:52:13 +0800
committerAndrew Morton <akpm@linux-foundation.org>2024-12-05 19:54:46 -0800
commit51f43d5d82ed2ba3f9a3f9a2390c52f28e42af32 (patch)
tree961b53d177c732103bfef31aed4c748d6090b874
parent914eec5e980171bc128e7e24f7a22aa1d803570e (diff)
mm/codetag: swap tags when migrate pages
Current solution to adjust codetag references during page migration is done in 3 steps: 1. sets the codetag reference of the old page as empty (not pointing to any codetag); 2. subtracts counters of the new page to compensate for its own allocation; 3. sets codetag reference of the new page to point to the codetag of the old page. This does not work if CONFIG_MEM_ALLOC_PROFILING_DEBUG=n because set_codetag_empty() becomes NOOP. Instead, let's simply swap codetag references so that the new page is referencing the old codetag and the old page is referencing the new codetag. This way accounting stays valid and the logic makes more sense. Link: https://lkml.kernel.org/r/20241129025213.34836-1-00107082@163.com Fixes: e0a955bf7f61 ("mm/codetag: add pgalloc_tag_copy()") Signed-off-by: David Wang <00107082@163.com> Closes: https://lore.kernel.org/lkml/20241124074318.399027-1-00107082@163.com/ Acked-by: Suren Baghdasaryan <surenb@google.com> Suggested-by: Suren Baghdasaryan <surenb@google.com> Acked-by: Yu Zhao <yuzhao@google.com> Cc: Kent Overstreet <kent.overstreet@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--include/linux/pgalloc_tag.h4
-rw-r--r--lib/alloc_tag.c36
-rw-r--r--mm/migrate.c2
3 files changed, 25 insertions, 17 deletions
diff --git a/include/linux/pgalloc_tag.h b/include/linux/pgalloc_tag.h
index 0e43ab653ab6..3469c4b20105 100644
--- a/include/linux/pgalloc_tag.h
+++ b/include/linux/pgalloc_tag.h
@@ -231,7 +231,7 @@ static inline void pgalloc_tag_sub_pages(struct alloc_tag *tag, unsigned int nr)
}
void pgalloc_tag_split(struct folio *folio, int old_order, int new_order);
-void pgalloc_tag_copy(struct folio *new, struct folio *old);
+void pgalloc_tag_swap(struct folio *new, struct folio *old);
void __init alloc_tag_sec_init(void);
@@ -245,7 +245,7 @@ static inline struct alloc_tag *pgalloc_tag_get(struct page *page) { return NULL
static inline void pgalloc_tag_sub_pages(struct alloc_tag *tag, unsigned int nr) {}
static inline void alloc_tag_sec_init(void) {}
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) {}
+static inline void pgalloc_tag_swap(struct folio *new, struct folio *old) {}
#endif /* CONFIG_MEM_ALLOC_PROFILING */
diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
index 2414a7ee7ec7..35f7560a309a 100644
--- a/lib/alloc_tag.c
+++ b/lib/alloc_tag.c
@@ -189,26 +189,34 @@ void pgalloc_tag_split(struct folio *folio, int old_order, int new_order)
}
}
-void pgalloc_tag_copy(struct folio *new, struct folio *old)
+void pgalloc_tag_swap(struct folio *new, struct folio *old)
{
- union pgtag_ref_handle handle;
- union codetag_ref ref;
- struct alloc_tag *tag;
+ union pgtag_ref_handle handle_old, handle_new;
+ union codetag_ref ref_old, ref_new;
+ struct alloc_tag *tag_old, *tag_new;
- tag = pgalloc_tag_get(&old->page);
- if (!tag)
+ tag_old = pgalloc_tag_get(&old->page);
+ if (!tag_old)
+ return;
+ tag_new = pgalloc_tag_get(&new->page);
+ if (!tag_new)
return;
- if (!get_page_tag_ref(&new->page, &ref, &handle))
+ if (!get_page_tag_ref(&old->page, &ref_old, &handle_old))
return;
+ if (!get_page_tag_ref(&new->page, &ref_new, &handle_new)) {
+ put_page_tag_ref(handle_old);
+ return;
+ }
+
+ /* swap tags */
+ __alloc_tag_ref_set(&ref_old, tag_new);
+ update_page_tag_ref(handle_old, &ref_old);
+ __alloc_tag_ref_set(&ref_new, tag_old);
+ update_page_tag_ref(handle_new, &ref_new);
- /* 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_size(new));
- __alloc_tag_ref_set(&ref, tag);
- update_page_tag_ref(handle, &ref);
- put_page_tag_ref(handle);
+ put_page_tag_ref(handle_old);
+ put_page_tag_ref(handle_new);
}
static void shutdown_mem_profiling(bool remove_file)
diff --git a/mm/migrate.c b/mm/migrate.c
index 2ce6b4b814df..cc68583c86f9 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -745,7 +745,7 @@ void folio_migrate_flags(struct folio *newfolio, struct folio *folio)
folio_set_readahead(newfolio);
folio_copy_owner(newfolio, folio);
- pgalloc_tag_copy(newfolio, folio);
+ pgalloc_tag_swap(newfolio, folio);
mem_cgroup_migrate(folio, newfolio);
}