Commit 3fcd76e8 authored Jul 08, 2013 by Zhang Yanfei Committed by Linus Torvalds Jul 09, 2013

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>

parent ab15d9b4

mm/vmalloc.c

+1 −15

Original line number	Diff line number	Diff line
		@@ -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();

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