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mm/vmalloc.c: remove dead code in vb_alloc

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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>
This commit is contained in:
Zhang Yanfei 2013-07-08 15:59:54 -07:00 committed by Linus Torvalds
parent ab15d9b4cb
commit 3fcd76e802
1 changed files with 1 additions and 15 deletions
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16
mm/vmalloc.c
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@ -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 @@ static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
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 @@ static void *vb_alloc(unsigned long size, gfp_t gfp_mask)
spin_unlock(&vb->lock);
}
if (purge)
purge_fragmented_blocks_thiscpu();
put_cpu_var(vmap_block_queue);
rcu_read_unlock();