Now that we have the folio_owner_ops callback, use it for hugetlb
pages instead of using a dedicated callback.
Since owner_ops is overlaid with lru, we need to unset owner_ops
to allow the use of lru when its isolated. At that point we know
that the reference count is elevated, will not reach 0, and thus
not trigger a callback. Therefore, it is safe to do so provided
we restore it before we put the folio back.
Signed-off-by: Fuad Tabba <tabba@xxxxxxxxxx>
---
include/linux/hugetlb.h | 2 --
mm/hugetlb.c | 57 +++++++++++++++++++++++++++++++++--------
mm/swap.c | 14 ----------
3 files changed, 47 insertions(+), 26 deletions(-)
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index e846d7dac77c..500848862702 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -20,8 +20,6 @@ struct user_struct;
struct mmu_gather;
struct node;
-void free_huge_folio(struct folio *folio);
-
#ifdef CONFIG_HUGETLB_PAGE
#include <linux/pagemap.h>
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 2308e94d8615..4e1c87e37968 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -89,6 +89,33 @@ static void __hugetlb_vma_unlock_write_free(struct vm_area_struct *vma);
static void hugetlb_unshare_pmds(struct vm_area_struct *vma,
unsigned long start, unsigned long end);
static struct resv_map *vma_resv_map(struct vm_area_struct *vma);
+static void free_huge_folio(struct folio *folio);
+
+static const struct folio_owner_ops hugetlb_owner_ops = {
+ .free = free_huge_folio,
+};
+
+/*
+ * Mark this folio as a hugetlb-owned folio.
+ *
+ * Set the folio hugetlb flag and owner operations.
+ */
+static void folio_set_hugetlb_owner(struct folio *folio)
+{
+ __folio_set_hugetlb(folio);
+ folio_set_owner_ops(folio, &hugetlb_owner_ops);
+}
+
+/*
+ * Unmark this folio from being a hugetlb-owned folio.
+ *
+ * Clear the folio hugetlb flag and owner operations.
+ */
+static void folio_clear_hugetlb_owner(struct folio *folio)
+{
+ folio_clear_owner_ops(folio);
+ __folio_clear_hugetlb(folio);
+}
static void hugetlb_free_folio(struct folio *folio)
{
@@ -1617,7 +1644,7 @@ static void remove_hugetlb_folio(struct hstate *h, struct folio *folio,
* to tail struct pages.
*/
if (!folio_test_hugetlb_vmemmap_optimized(folio)) {
- __folio_clear_hugetlb(folio);
+ folio_clear_hugetlb_owner(folio);
}
h->nr_huge_pages--;
@@ -1641,7 +1668,7 @@ static void add_hugetlb_folio(struct hstate *h, struct folio *folio,
h->surplus_huge_pages++;
h->surplus_huge_pages_node[nid]++;
}
- __folio_set_hugetlb(folio);
+ folio_set_hugetlb_owner(folio);
folio_change_private(folio, NULL);
/*
@@ -1692,7 +1719,7 @@ static void __update_and_free_hugetlb_folio(struct hstate *h,
*/
if (folio_test_hugetlb(folio)) {
spin_lock_irq(&hugetlb_lock);
- __folio_clear_hugetlb(folio);
+ folio_clear_hugetlb_owner(folio);
spin_unlock_irq(&hugetlb_lock);
}
@@ -1793,7 +1820,7 @@ static void bulk_vmemmap_restore_error(struct hstate *h,
list_for_each_entry_safe(folio, t_folio, non_hvo_folios, _hugetlb_list) {
list_del(&folio->_hugetlb_list);
spin_lock_irq(&hugetlb_lock);
- __folio_clear_hugetlb(folio);
+ folio_clear_hugetlb_owner(folio);
spin_unlock_irq(&hugetlb_lock);
update_and_free_hugetlb_folio(h, folio, false);
cond_resched();
@@ -1818,7 +1845,7 @@ static void bulk_vmemmap_restore_error(struct hstate *h,
} else {
list_del(&folio->_hugetlb_list);
spin_lock_irq(&hugetlb_lock);
- __folio_clear_hugetlb(folio);
+ folio_clear_hugetlb_owner(folio);
spin_unlock_irq(&hugetlb_lock);
update_and_free_hugetlb_folio(h, folio, false);
cond_resched();
@@ -1851,14 +1878,14 @@ static void update_and_free_pages_bulk(struct hstate *h,
* should only be pages on the non_hvo_folios list.
* Do note that the non_hvo_folios list could be empty.
* Without HVO enabled, ret will be 0 and there is no need to call
- * __folio_clear_hugetlb as this was done previously.
+ * folio_clear_hugetlb_owner as this was done previously.
*/
VM_WARN_ON(!list_empty(folio_list));
VM_WARN_ON(ret < 0);
if (!list_empty(&non_hvo_folios) && ret) {
spin_lock_irq(&hugetlb_lock);
list_for_each_entry(folio, &non_hvo_folios, _hugetlb_list)
- __folio_clear_hugetlb(folio);
+ folio_clear_hugetlb_owner(folio);
spin_unlock_irq(&hugetlb_lock);
}
@@ -1879,7 +1906,7 @@ struct hstate *size_to_hstate(unsigned long size)
return NULL;
}
-void free_huge_folio(struct folio *folio)
+static void free_huge_folio(struct folio *folio)
{
/*
* Can't pass hstate in here because it is called from the
@@ -1959,7 +1986,7 @@ static void __prep_account_new_huge_page(struct hstate *h, int nid)
static void init_new_hugetlb_folio(struct hstate *h, struct folio *folio)
{
- __folio_set_hugetlb(folio);
+ folio_set_hugetlb_owner(folio);
INIT_LIST_HEAD(&folio->_hugetlb_list);
hugetlb_set_folio_subpool(folio, NULL);
set_hugetlb_cgroup(folio, NULL);
@@ -7428,6 +7455,14 @@ bool folio_isolate_hugetlb(struct folio *folio, struct list_head *list)
goto unlock;
}
folio_clear_hugetlb_migratable(folio);
+ /*
+ * Clear folio->owner_ops; now we can use folio->lru.
+ * Note that the folio cannot get freed because we are holding a
+ * reference. The reference will be put in folio_putback_hugetlb(),
+ * after restoring folio->owner_ops.
+ */
+ folio_clear_owner_ops(folio);
+ INIT_LIST_HEAD(&folio->lru);
list_del_init(&folio->_hugetlb_list);
list_add_tail(&folio->lru, list);
unlock:
@@ -7480,7 +7515,9 @@ void folio_putback_hugetlb(struct folio *folio)
{
spin_lock_irq(&hugetlb_lock);
folio_set_hugetlb_migratable(folio);
- list_del_init(&folio->lru);
+ list_del(&folio->lru);
+ /* Restore folio->owner_ops since we can no longer use folio->lru. */
+ folio_set_owner_ops(folio, &hugetlb_owner_ops);
list_add_tail(&folio->_hugetlb_list, &(folio_hstate(folio))->hugepage_activelist);
spin_unlock_irq(&hugetlb_lock);
folio_put(folio);
diff --git a/mm/swap.c b/mm/swap.c
index d2578465e270..9798ca47f26a 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -117,11 +117,6 @@ void __folio_put(struct folio *folio)
return;
}
- if (folio_test_hugetlb(folio)) {
- free_huge_folio(folio);
- return;
- }
-
page_cache_release(folio);
folio_unqueue_deferred_split(folio);
mem_cgroup_uncharge(folio);
@@ -953,15 +948,6 @@ void folios_put_refs(struct folio_batch *folios, unsigned int *refs)
if (!folio_ref_sub_and_test(folio, nr_refs))
continue;
- /* hugetlb has its own memcg */
- if (folio_test_hugetlb(folio)) {
- if (lruvec) {
- unlock_page_lruvec_irqrestore(lruvec, flags);
- lruvec = NULL;
- }
- free_huge_folio(folio);
- continue;
- }
folio_unqueue_deferred_split(folio);
__page_cache_release(folio, &lruvec, &flags);
--
2.47.0.277.g8800431eea-goog
