mm: percpu-vmap fix RCU list walking
RCU list walking of the per-cpu vmap cache was broken. It did not use
RCU primitives, and also the union of free_list and rcu_head is
obviously wrong (because free_list is indeed the list we are RCU
walking).
While we are there, remove a couple of unused fields from an earlier
iteration.
These APIs aren't actually used anywhere, because of problems with the
XFS conversion. Christoph has now verified that the problems are solved
with these patches. Also it is an exported interface, so I think it
will be good to be merged now (and Christoph wants to get the XFS
changes into their local tree).
Cc: stable@kernel.org
Cc: linux-mm@kvack.org
Tested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Nick Piggin <npiggin@suse.de>
--
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d55d905..cf76ff6 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -667,8 +667,6 @@
struct vmap_block_queue {
spinlock_t lock;
struct list_head free;
- struct list_head dirty;
- unsigned int nr_dirty;
};
struct vmap_block {
@@ -678,10 +676,8 @@
unsigned long free, dirty;
DECLARE_BITMAP(alloc_map, VMAP_BBMAP_BITS);
DECLARE_BITMAP(dirty_map, VMAP_BBMAP_BITS);
- union {
- struct list_head free_list;
- struct rcu_head rcu_head;
- };
+ struct list_head free_list;
+ struct rcu_head rcu_head;
};
/* Queue of free and dirty vmap blocks, for allocation and flushing purposes */
@@ -757,7 +753,7 @@
vbq = &get_cpu_var(vmap_block_queue);
vb->vbq = vbq;
spin_lock(&vbq->lock);
- list_add(&vb->free_list, &vbq->free);
+ list_add_rcu(&vb->free_list, &vbq->free);
spin_unlock(&vbq->lock);
put_cpu_var(vmap_block_queue);
@@ -776,8 +772,6 @@
struct vmap_block *tmp;
unsigned long vb_idx;
- BUG_ON(!list_empty(&vb->free_list));
-
vb_idx = addr_to_vb_idx(vb->va->va_start);
spin_lock(&vmap_block_tree_lock);
tmp = radix_tree_delete(&vmap_block_tree, vb_idx);
@@ -816,7 +810,7 @@
vb->free -= 1UL << order;
if (vb->free == 0) {
spin_lock(&vbq->lock);
- list_del_init(&vb->free_list);
+ list_del_rcu(&vb->free_list);
spin_unlock(&vbq->lock);
}
spin_unlock(&vb->lock);
@@ -860,11 +854,11 @@
BUG_ON(!vb);
spin_lock(&vb->lock);
- bitmap_allocate_region(vb->dirty_map, offset >> PAGE_SHIFT, order);
+ BUG_ON(bitmap_allocate_region(vb->dirty_map, offset >> PAGE_SHIFT, order));
vb->dirty += 1UL << order;
if (vb->dirty == VMAP_BBMAP_BITS) {
- BUG_ON(vb->free || !list_empty(&vb->free_list));
+ BUG_ON(vb->free);
spin_unlock(&vb->lock);
free_vmap_block(vb);
} else
@@ -1033,8 +1027,6 @@
vbq = &per_cpu(vmap_block_queue, i);
spin_lock_init(&vbq->lock);
INIT_LIST_HEAD(&vbq->free);
- INIT_LIST_HEAD(&vbq->dirty);
- vbq->nr_dirty = 0;
}
/* Import existing vmlist entries. */
