[PATCH 42/62] vmalloc: Convert to xarray

Matthew Wilcox
2017-11-22T21:14:24Z

The radix tree of vmap blocks is simpler to express as an XArray.
Saves a couple of hundred bytes of text and eliminates a user of the
radix tree preload API.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
mm/vmalloc.c | 37 ++++++++++++-------------------------
1 file changed, 12 insertions(+), 25 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 673942094328..cc5de1ee6520 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -821,12 +821,11 @@ struct vmap_block {
static DEFINE_PER_CPU(struct vmap_block_queue, vmap_block_queue);

/*
- * Radix tree of vmap blocks, indexed by address, to quickly find a vmap block
+ * XArray of vmap blocks, indexed by address, to quickly find a vmap block
* in the free path. Could get rid of this if we change the API to return a
* "cookie" from alloc, to be passed to free. But no big deal yet.
*/
-static DEFINE_SPINLOCK(vmap_block_tree_lock);
-static RADIX_TREE(vmap_block_tree, GFP_ATOMIC);
+static DEFINE_XARRAY(vmap_block_tree);

/*
* We should probably have a fallback mechanism to allocate virtual memory
@@ -865,8 +864,8 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
struct vmap_block *vb;
struct vmap_area *va;
unsigned long vb_idx;
- int node, err;
- void *vaddr;
+ int node;
+ void *ret, *vaddr;

node = numa_node_id();

@@ -883,13 +882,6 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
return ERR_CAST(va);
}

- err = radix_tree_preload(gfp_mask);
- if (unlikely(err)) {
- kfree(vb);
- free_vmap_area(va);
- return ERR_PTR(err);
- }
-
vaddr = vmap_block_vaddr(va->va_start, 0);
spin_lock_init(&vb->lock);
vb->va = va;
@@ -902,11 +894,12 @@ static void *new_vmap_block(unsigned int order, gfp_t gfp_mask)
INIT_LIST_HEAD(&vb->free_list);

vb_idx = addr_to_vb_idx(va->va_start);
- spin_lock(&vmap_block_tree_lock);
- err = radix_tree_insert(&vmap_block_tree, vb_idx, vb);
- spin_unlock(&vmap_block_tree_lock);
- BUG_ON(err);
- radix_tree_preload_end();
+ ret = xa_store(&vmap_block_tree, vb_idx, vb, gfp_mask);
+ if (IS_ERR(ret)) {
+ kfree(vb);
+ free_vmap_area(va);
+ return ret;
+ }

vbq = &get_cpu_var(vmap_block_queue);
spin_lock(&vbq->lock);
@@ -923,9 +916,7 @@ static void free_vmap_block(struct vmap_block *vb)
unsigned long vb_idx;

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);
- spin_unlock(&vmap_block_tree_lock);
+ tmp = xa_store(&vmap_block_tree, vb_idx, NULL, GFP_NOWAIT);
BUG_ON(tmp != vb);

free_vmap_area_noflush(vb->va);
@@ -1031,7 +1022,6 @@ static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
static void vb_free(const void *addr, unsigned long size)
{
unsigned long offset;
- unsigned long vb_idx;
unsigned int order;
struct vmap_block *vb;

@@ -1045,10 +1035,7 @@ static void vb_free(const void *addr, unsigned long size)
offset = (unsigned long)addr & (VMAP_BLOCK_SIZE - 1);
offset >>= PAGE_SHIFT;

- vb_idx = addr_to_vb_idx((unsigned long)addr);
- rcu_read_lock();
- vb = radix_tree_lookup(&vmap_block_tree, vb_idx);
- rcu_read_unlock();
+ vb = xa_load(&vmap_block_tree, addr_to_vb_idx((unsigned long)addr));
BUG_ON(!vb);

vunmap_page_range((unsigned long)addr, (unsigned long)addr + size);
--
2.15.0