mm/vmalloc.c: remove dead code in vb_alloc

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.

[ Same patches also sent by:

    Chanho Min <chanho.min@lge.com>
    Johannes Weiner <hannes@cmpxchg.org>

  but git doesn't do "multiple authors" ]

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 96b77a9..a35f4f5 100644 (file)
--- 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();