diff mbox series

[11/11] PageSlab: eliminate unnecessary compound_head() calls in mm/memcontrol

Message ID 20211012180148.1669685-12-hannes@cmpxchg.org (mailing list archive)
State New
Headers show
Series PageSlab: eliminate unnecessary compound_head() calls | expand

Commit Message

Johannes Weiner Oct. 12, 2021, 6:01 p.m. UTC 
page->memcg_data is generally not valid on tailpages, so the accessor
functions don't need to worry about encountering them outside of
bugs. The only place where the memory controller may encounter tail
pages is in mem_cgroup_from_obj(), but that uses virt_to_head_page()
first thing to resolve slab objects to slab pages.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 include/linux/memcontrol.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 02394f802698..3096c9a0ee01 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -397,7 +397,7 @@  static inline struct mem_cgroup *__page_memcg(struct page *page)
 {
 	unsigned long memcg_data = page->memcg_data;
 
-	VM_BUG_ON_PAGE(PageSlab(compound_head(page)), page);
+	VM_BUG_ON_PAGE(PageSlab(page), page);
 	VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_OBJCGS, page);
 	VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_KMEM, page);
 
@@ -418,7 +418,7 @@  static inline struct obj_cgroup *__page_objcg(struct page *page)
 {
 	unsigned long memcg_data = page->memcg_data;
 
-	VM_BUG_ON_PAGE(PageSlab(compound_head(page)), page);
+	VM_BUG_ON_PAGE(PageSlab(page), page);
 	VM_BUG_ON_PAGE(memcg_data & MEMCG_DATA_OBJCGS, page);
 	VM_BUG_ON_PAGE(!(memcg_data & MEMCG_DATA_KMEM), page);
 
@@ -466,7 +466,7 @@  static inline struct mem_cgroup *page_memcg_rcu(struct page *page)
 {
 	unsigned long memcg_data = READ_ONCE(page->memcg_data);
 
-	VM_BUG_ON_PAGE(PageSlab(compound_head(page)), page);
+	VM_BUG_ON_PAGE(PageSlab(page), page);
 	WARN_ON_ONCE(!rcu_read_lock_held());
 
 	if (memcg_data & MEMCG_DATA_KMEM) {