From: Roland Dreier Date: Mon, 15 May 2006 18:41:00 +0000 (-0700) Subject: [PATCH] slab: Fix kmem_cache_destroy() on NUMA X-Git-Tag: v2.6.17-rc5~112 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a4523a8b38089478f93bc053c31f678c63f5ee1b;p=pandora-kernel.git [PATCH] slab: Fix kmem_cache_destroy() on NUMA With CONFIG_NUMA set, kmem_cache_destroy() may fail and say "Can't free all objects." The problem is caused by sequences such as the following (suppose we are on a NUMA machine with two nodes, 0 and 1): * Allocate an object from cache on node 0. * Free the object on node 1. The object is put into node 1's alien array_cache for node 0. * Call kmem_cache_destroy(), which ultimately ends up in __cache_shrink(). * __cache_shrink() does drain_cpu_caches(), which loops through all nodes. For each node it drains the shared array_cache and then handles the alien array_cache for the other node. However this means that node 0's shared array_cache will be drained, and then node 1 will move the contents of its alien[0] array_cache into that same shared array_cache. node 0's shared array_cache is never looked at again, so the objects left there will appear to be in use when __cache_shrink() calls __node_shrink() for node 0. So __node_shrink() will return 1 and kmem_cache_destroy() will fail. This patch fixes this by having drain_cpu_caches() do drain_alien_cache() on every node before it does drain_array() on the nodes' shared array_caches. The problem was originally reported by Or Gerlitz . Signed-off-by: Roland Dreier Acked-by: Christoph Lameter Acked-by: Pekka Enberg Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed