Messages in this thread | | | Date | Thu, 29 Nov 2012 14:34:52 -0500 | From | Benjamin LaHaise <> | Subject | Re: [PATCH 22/25] Generic dynamic per cpu refcounting |
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On Thu, Nov 29, 2012 at 11:29:25AM -0800, Kent Overstreet wrote: > There's some kind of symmetry going on here, and if I'd been awake more > in college I could probably say exactly why it works, but it does.
I think the catch is that using only a 32 bit counter is something the user could arbitrarily control the sum of all parts. I think a 64 bit counter may be required to ensure no overflow occurs. Otherwise, an overflow could result in a premature free when there are still 2^32 objects active thanks to a malicious user (possible on systems with lots of memory these days -- remote, but possible).
-ben -- "Thought is the essence of where you are now."
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