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authorAndi Kleen <ak@suse.de>2005-02-11 02:03:52 -0800
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-02-11 02:03:52 -0800
commit1dbd4652aedfc6e0a77b431bb27fb3713eba6338 (patch)
parent0f8c793dfad651a0162f27a7bfc7c80309f4a297 (diff)
[PATCH] Fix small vmalloc per allocation limit
The vmap vmalloc rework in 2.5 had a unintended side effect. vmalloc uses kmalloc now to allocate an array with a list of pages. kmalloc has a 128K maximum. This limits the vmalloc maximum size to 64MB on a 64bit system with 4K pages. That limit causes problems with other subsystems, e.g. iptables relies on allocating large vmallocs for its rule sets. This is a bug IMHO - on 64bit platforms there shouldn't be such a low limit on the vmalloc size. And even on 32bit it's too small for custom kernels with enlarged vmalloc area. Another problem is that this makes vmalloc unreliable. After the system has been running for some time it is unlikely that kmalloc will be able to allocate >order 2 pages due to memory fragmentation. This patch takes the easy way out for fixing this by just allocating this array with vmalloc when it is larger than a page. While more complicated and intrusive solutions would be possible they didn't use vmalloc recursively they didn't seem it worth to handle this very infrequent case. Please note that the vmalloc recursion is strictly bounded because each nested allocation will generate a much smaller stack frame. Also the kernel stack can handle even a few recursion steps easily because vmalloc has only a small stack frame. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 files changed, 10 insertions, 2 deletions
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index e0fa3b39f2d1..e6516c208d62 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -378,7 +378,10 @@ void __vunmap(void *addr, int deallocate_pages)
- kfree(area->pages);
+ if (area->nr_pages > PAGE_SIZE/sizeof(struct page *))
+ vfree(area->pages);
+ else
+ kfree(area->pages);
@@ -482,7 +485,12 @@ void *__vmalloc(unsigned long size, int gfp_mask, pgprot_t prot)
array_size = (nr_pages * sizeof(struct page *));
area->nr_pages = nr_pages;
- area->pages = pages = kmalloc(array_size, (gfp_mask & ~__GFP_HIGHMEM));
+ /* Please note that the recursion is strictly bounded. */
+ if (array_size > PAGE_SIZE)
+ pages = __vmalloc(array_size, gfp_mask, PAGE_KERNEL);
+ else
+ pages = kmalloc(array_size, (gfp_mask & ~__GFP_HIGHMEM));
+ area->pages = pages;
if (!area->pages) {