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Message-Id: <200907170144.27775.vda.linux@googlemail.com> Date: Fri, 17 Jul 2009 01:44:27 +0200 From: Denys Vlasenko <vda.linux@...glemail.com> To: Valdis.Kletnieks@...edu Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] add "VmUsers: N" to /proc/$PID/status On Friday 17 July 2009 01:24, Valdis.Kletnieks@...edu wrote: > > I, indeed, want to have just an N I can divide RSS/VSZ/etc by, > > to get, say, top display which do not mislead user > > into thinking that he has 3 processes with 100 megabyte RSS > > when in reality he has 3 processes sharing a single VM > > with 100 meg RSS. > > Thinking about it a bit more - it's probably *usually* possible to sort out > which processes are sharing because if you have 2 sets of shared memory, > they'll *usually* have different RSS values - so the 2 processes with a > count of 2 and an RSS of 179M are one set, and the 2 processes with a count > of 2 and an RSS of 198M are probably another. Hmm. We can just expose the raw value of task->mm pointer. For all tasks which share a VM, it will have the same value. It would be an "information leak", yes, but it isn't obvious whether it can be exploited at all. We can also obscure it a bit by XORing or summing it with randomly selected constant or some such. -- vda -- 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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