Messages in this thread Patch in this message | | | Date | Sun, 2 Dec 2007 17:43:09 +0100 | From | "Vegard Nossum" <> | Subject | Re: [BUG 2.6.24-rc3-git6] SLUB's ksize() fails for size > 2048. |
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On Dec 2, 2007 5:30 PM, Vegard Nossum <vegard.nossum@gmail.com> wrote: > On Dec 2, 2007 11:39 AM, Tetsuo Handa > <penguin-kernel@i-love.sakura.ne.jp> 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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