On Dec 2, 2007 5:30 PM, Vegard Nossum <[email protected]> wrote:
> On Dec 2, 2007 11:39 AM, Tetsuo Handa
> <[email protected]> wrote:
> > Hello.
> >
> > 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.
> >
> > Regards.
> The error of ksize() seems to be that it does not check if the
> allocation was made by SLUB or the page allocator. Maybe something
> like this will fix it? (completely untested)
That didn't work. I guess that's what you get for no testing ;-) After
some more investigations, it seems that this is the correct way to fix
it (and tested!):
diff --git a/mm/slub.c b/mm/slub.c
index 9acb413..b9f37cb 100644
--- 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);
> It's going to round up, though, so you would get ksize(kmalloc(2049))
> = PAGE_SIZE.
Vegard
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