[PATCH 1/3] mm, vmalloc: Remove dead code in vb_alloc

Zhang Yanfei
2013-06-07T09:56:22Z

Space in a vmap block that was once allocated is considered dirty and
not made available for allocation again before the whole block is
recycled. The result is that free space within a vmap block is always
contiguous.

So if a vmap block has enough free space for allocation, the allocation
is impossible to fail. Thus, the fragmented block purging was never invoked
from vb_alloc(). So remove this dead code.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
---
mm/vmalloc.c | 16 +---------------
1 files changed, 1 insertions(+), 15 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d365724..b8abcba 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -910,7 +910,6 @@ static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
struct vmap_block *vb;
unsigned long addr = 0;
unsigned int order;
- int purge = 0;

BUG_ON(size & ~PAGE_MASK);
BUG_ON(size > PAGE_SIZE*VMAP_MAX_ALLOC);
@@ -934,17 +933,7 @@ again:
if (vb->free < 1UL << order)
goto next;

- i = bitmap_find_free_region(vb->alloc_map,
- VMAP_BBMAP_BITS, order);
-
- if (i < 0) {
- if (vb->free + vb->dirty == VMAP_BBMAP_BITS) {
- /* fragmented and no outstanding allocations */
- BUG_ON(vb->dirty != VMAP_BBMAP_BITS);
- purge = 1;
- }
- goto next;
- }
+ i = VMAP_BBMAP_BITS - vb->free;
addr = vb->va->va_start + (i << PAGE_SHIFT);
BUG_ON(addr_to_vb_idx(addr) !=
addr_to_vb_idx(vb->va->va_start));
@@ -960,9 +949,6 @@ next:
spin_unlock(&vb->lock);
}

- if (purge)
- purge_fragmented_blocks_thiscpu();
-
put_cpu_var(vmap_block_queue);
rcu_read_unlock();

--
1.7.1