[PATCH v2 06/23] vmw_balloon: stop using the balloon_dev_info lock

David Hildenbrand (Red Hat)
2026-01-15T09:21:15Z

Let's not piggy-back on the existing lock and use a separate lock for the
huge page list. Now that we use a separate lock, there is no need to
disable interrupts, so use the non-irqsave variants.

This is a preparation for changing the locking used to protect
balloon_dev_info.

While at it, talk about "page migration" instead of "page compaction".
We'll change that in core code soon as well.

Signed-off-by: David Hildenbrand (Red Hat) <david@kernel.org>
---
drivers/misc/vmw_balloon.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
index 52b8c0f1eead7..53e9335b6718c 100644
--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -354,10 +354,15 @@ struct vmballoon {
/**
* @huge_pages - list of the inflated 2MB pages.
*
- * Protected by @b_dev_info.pages_lock .
+ * Protected by @huge_pages_lock.
*/
struct list_head huge_pages;

+ /**
+ * @huge_pages_lock: lock for the list of inflated 2MB pages.
+ */
+ spinlock_t huge_pages_lock;
+
/**
* @vmci_doorbell.
*
@@ -987,7 +992,6 @@ static void vmballoon_enqueue_page_list(struct vmballoon *b,
unsigned int *n_pages,
enum vmballoon_page_size_type page_size)
{
- unsigned long flags;
struct page *page;

if (page_size == VMW_BALLOON_4K_PAGE) {
@@ -995,9 +999,9 @@ static void vmballoon_enqueue_page_list(struct vmballoon *b,
} else {
/*
* Keep the huge pages in a local list which is not available
- * for the balloon compaction mechanism.
+ * for the balloon page migration.
*/
- spin_lock_irqsave(&b->b_dev_info.pages_lock, flags);
+ spin_lock(&b->huge_pages_lock);

list_for_each_entry(page, pages, lru) {
vmballoon_mark_page_offline(page, VMW_BALLOON_2M_PAGE);
@@ -1006,7 +1010,7 @@ static void vmballoon_enqueue_page_list(struct vmballoon *b,
list_splice_init(pages, &b->huge_pages);
__count_vm_events(BALLOON_INFLATE, *n_pages *
vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE));
- spin_unlock_irqrestore(&b->b_dev_info.pages_lock, flags);
+ spin_unlock(&b->huge_pages_lock);
}

*n_pages = 0;
@@ -1033,7 +1037,6 @@ static void vmballoon_dequeue_page_list(struct vmballoon *b,
{
struct page *page, *tmp;
unsigned int i = 0;
- unsigned long flags;

/* In the case of 4k pages, use the compaction infrastructure */
if (page_size == VMW_BALLOON_4K_PAGE) {
@@ -1043,7 +1046,7 @@ static void vmballoon_dequeue_page_list(struct vmballoon *b,
}

/* 2MB pages */
- spin_lock_irqsave(&b->b_dev_info.pages_lock, flags);
+ spin_lock(&b->huge_pages_lock);
list_for_each_entry_safe(page, tmp, &b->huge_pages, lru) {
vmballoon_mark_page_online(page, VMW_BALLOON_2M_PAGE);

@@ -1054,7 +1057,7 @@ static void vmballoon_dequeue_page_list(struct vmballoon *b,

__count_vm_events(BALLOON_DEFLATE,
i * vmballoon_page_in_frames(VMW_BALLOON_2M_PAGE));
- spin_unlock_irqrestore(&b->b_dev_info.pages_lock, flags);
+ spin_unlock(&b->huge_pages_lock);
*n_pages = i;
}

@@ -1828,6 +1831,7 @@ static int __init vmballoon_init(void)
balloon.b_dev_info.migratepage = vmballoon_migratepage;

INIT_LIST_HEAD(&balloon.huge_pages);
+ spin_lock_init(&balloon.huge_pages_lock);
spin_lock_init(&balloon.comm_lock);
init_rwsem(&balloon.conf_sem);
balloon.vmci_doorbell = VMCI_INVALID_HANDLE;
--
2.52.0