SLUB's ksize() fails for size > 2048

I can't pass memory allocated by kmalloc() to ksize() if it is allocated by
SLUB allocator and size is larger than (I guess) PAGE_SIZE / 2.

The error of ksize() seems to be that it does not check if the allocation
was made by SLUB or the page allocator.

Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Christoph Lameter <clameter@sgi.com>, Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/slub.c b/mm/slub.c
index 9acb413..b9f37cb 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2558,8 +2558,12 @@ size_t ksize(const void *object)
        if (unlikely(object == ZERO_SIZE_PTR))
                return 0;
 
-       page = get_object_page(object);
+       page = virt_to_head_page(object);
        BUG_ON(!page);
+
+       if (unlikely(!PageSlab(page)))
+               return PAGE_SIZE << compound_order(page);
+
        s = page->slab;
        BUG_ON(!s);