[PATCH] Fix GFP_HIGHMEM slab panic

As reported by Martin J. Bligh <mbligh@google.com>, we let through some
non-slab bits to slab allocation through __get_vm_area_node when doing a
vmalloc.

I haven't been able to reproduce this, although I understand why it
happens: vmalloc allocates memory with

GFP_KERNEL | __GFP_HIGHMEM

and commit 52fd24ca1db3a741f144bbc229beefe044202cac resulted in the same
flags are passed down to cache_alloc_refill, causing the BUG.  The
following patch fixes it.

Note that when calling kmalloc_node, I am masking off __GFP_HIGHMEM with
GFP_LEVEL_MASK, whereas __vmalloc_area_node does the same with

~(__GFP_HIGHMEM | __GFP_ZERO).

IMHO, using GFP_LEVEL_MASK is preferable, but either should fix this
problem.

Signed-off-by: Giridhar Pemmasani (pgiri@yahoo.com)
Cc: Martin J. Bligh <mbligh@google.com>
Cc: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 6d381df7c9b39758f5c978a3de8383963ec06afc..46606c133e824ea4a12f8ae7ca818c333a938628 100644 (file)
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -182,7 +182,7 @@ static struct vm_struct *__get_vm_area_node(unsigned long size, unsigned long fl
        addr = ALIGN(start, align);
        size = PAGE_ALIGN(size);
 
-       area = kmalloc_node(sizeof(*area), gfp_mask, node);
+       area = kmalloc_node(sizeof(*area), gfp_mask & GFP_LEVEL_MASK, node);
        if (unlikely(!area))
                return NULL;