From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by rv-out-0910.google.com with SMTP id l15so2210803rvb for ; Sun, 02 Dec 2007 08:43:09 -0800 (PST) Message-ID: <19f34abd0712020843m1dccfa3bu38388e1a53b05fc@mail.gmail.com> 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. In-Reply-To: <19f34abd0712020830y4825691atdfc9dac07ce4cb35@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <200712021939.HHH18792.FLQSOOtFOFJVHM@I-love.SAKURA.ne.jp> <19f34abd0712020830y4825691atdfc9dac07ce4cb35@mail.gmail.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Tetsuo Handa Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Dec 2, 2007 5:30 PM, Vegard Nossum wrote: > On Dec 2, 2007 11:39 AM, Tetsuo Handa > 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org