On 25.11.24 22:01, Matthew Wilcox (Oracle) wrote:
Since slab does not use the page refcount, it can allocate and
free frozen pages, saving one atomic operation per free.
Reviewed-by: William Kucharski <william.kucharski@xxxxxxxxxx>
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
mm/slub.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index 19980419b176..3d0c1cd6bdf5 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2405,9 +2405,9 @@ static inline struct slab *alloc_slab_page(gfp_t flags, int node,
unsigned int order = oo_order(oo);
if (node == NUMA_NO_NODE)
- folio = (struct folio *)alloc_pages(flags, order);
+ folio = (struct folio *)alloc_frozen_pages(flags, order);
else
- folio = (struct folio *)__alloc_pages_node(node, flags, order);
+ folio = (struct folio *)__alloc_frozen_pages(flags, order, node, NULL);
if (!folio)
return NULL;
@@ -2641,7 +2641,7 @@ static void __free_slab(struct kmem_cache *s, struct slab *slab)
__folio_clear_slab(folio);
mm_account_reclaimed_pages(pages);
unaccount_slab(slab, order, s);
- __free_pages(&folio->page, order);
+ free_frozen_pages(&folio->page, order);
}
static void rcu_free_slab(struct rcu_head *h)
I think we discussed in v1 or v2 that page isolation should be taught about that.
Likely we want something like:
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 7e04047977cfe..7db2f79b39f0d 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -101,6 +101,8 @@ static struct page *has_unmovable_pages(unsigned long start_pfn, unsigned long e
* because their page->_refcount is zero at all time.
*/
if (!page_ref_count(page)) {
+ if (PageSlab(page))
+ return page;
if (PageBuddy(page))
pfn += (1 << buddy_order(page)) - 1;
continue;
--
Cheers,
David / dhildenb
