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Message-ID: <Pine.LNX.4.64.0706012139480.11577@schroedinger.engr.sgi.com> Date: Fri, 1 Jun 2007 21:45:15 -0700 (PDT) From: Christoph Lameter <clameter@....com> To: Andrew Morton <akpm@...ux-foundation.org> cc: linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org, jeremy@...p.org Subject: Re: SLUB: Return ZERO_SIZE_PTR for kmalloc(0) On Fri, 1 Jun 2007, Andrew Morton wrote: > They are different instances which happen to have the same length (zero). I guess one could use the slab allocators as a type of reservation ticket generator with zero sized objects. Hmmm.... But is that really a useful thing to do? > But the code will incorrectly decide that they are the same instance. It > might cause refcounting or accounting errors, for example. I don't know - the > kernel's a big place. That would have to occur with objects that are repeatedly allocated and then linked toghether etc. Linking typicallty requires a listhead so its typically difficult to do zero length objects. > I agree the risk is low, but if something _does_ blow up, it will do so subtly. The cases that we have seen so far are due to array allocations of N elements where N == 0 leads to the creation of a zero sized object. The objects of the array are not zero sized it is just that zero of them are allocated. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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