Commit 92ca922f authored Jul 31, 2012 by Hong zhi guo Committed by Linus Torvalds Jul 31, 2012

vmalloc: walk vmap_areas by sorted list instead of rb_next()



There's a walk by repeating rb_next to find a suitable hole.  Could be
simply replaced by walk on the sorted vmap_area_list.  More simpler and
efficient.

Mutation of the list and tree only happens in pair within
__insert_vmap_area and __free_vmap_area, under protection of
vmap_area_lock.  The patch code is also under vmap_area_lock, so the list
walk is safe, and consistent with the tree walk.

Tested on SMP by repeating batch of vmalloc anf vfree for random sizes and
rounds for hours.

Signed-off-by: Hong Zhiguo <honkiko@gmail.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent c2cddf99

mm/vmalloc.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -413,11 +413,11 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
		if (addr + size - 1 < addr)
		goto overflow;

		n = rb_next(&first->rb_node);
		if (n)
		first = rb_entry(n, struct vmap_area, rb_node);
		else
		if (list_is_last(&first->list, &vmap_area_list))
		goto found;

		first = list_entry(first->list.next,
		struct vmap_area, list);
		}

		found: