[patch 5/6] mm/vmalloc: Add missing READ/WRITE_ONCE() annotations

Thomas Gleixner
2023-05-23T14:10:15Z

purge_fragmented_blocks() accesses vmap_block::free and vmap_block::dirty
lockless for a quick check.

Add the missing READ/WRITE_ONCE() annotations.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
mm/vmalloc.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2093,9 +2093,9 @@ static bool purge_fragmented_block(struc
return false;

/* prevent further allocs after releasing lock */
- vb->free = 0;
+ WRITE_ONCE(vb->free, 0);
/* prevent purging it again */
- vb->dirty = VMAP_BBMAP_BITS;
+ WRITE_ONCE(vb->dirty, VMAP_BBMAP_BITS);
vb->dirty_min = 0;
vb->dirty_max = VMAP_BBMAP_BITS;
spin_lock(&vbq->lock);
@@ -2123,7 +2123,10 @@ static void purge_fragmented_blocks(int

rcu_read_lock();
list_for_each_entry_rcu(vb, &vbq->free, free_list) {
- if (!(vb->free + vb->dirty == VMAP_BBMAP_BITS && vb->dirty != VMAP_BBMAP_BITS))
+ unsigned long free = READ_ONCE(vb->free);
+ unsigned long dirty = READ_ONCE(vb->dirty);
+
+ if (!(free + dirty == VMAP_BBMAP_BITS && dirty != VMAP_BBMAP_BITS))
continue;

spin_lock(&vb->lock);
@@ -2231,7 +2234,7 @@ static void vb_free(unsigned long addr,
vb->dirty_min = min(vb->dirty_min, offset);
vb->dirty_max = max(vb->dirty_max, offset + (1UL << order));

- vb->dirty += 1UL << order;
+ WRITE_ONCE(vb->dirty, vb->dirty + (1UL << order));
if (vb->dirty == VMAP_BBMAP_BITS) {
BUG_ON(vb->free);
spin_unlock(&vb->lock);