Messages in this thread | | | Subject | Re: [PATCH 10/11] maps3: add /proc/kpagecount and /proc/kpageflags interfaces | From | Dave Hansen <> | Date | Mon, 15 Oct 2007 15:48:33 -0700 |
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On Mon, 2007-10-15 at 17:26 -0500, Matt Mackall wrote: > From: Matt Mackall <mpm@selenic.com> > > This makes physical page map counts available to userspace. Together > with /proc/pid/pagemap and /proc/pid/clear_refs, this can be used to > monitor memory usage on a per-page basis. ... > + while (count > 0) { > + ppage = pfn_to_page(pfn++); > + if (!ppage) > + pflags = 0; > + else > + pflags = ppage->flags; > +
This one makes me worry a little bit. Are we sure that this won't expose a wee bit too much to userspace?
I can see it making sense to clear the page refs, then inspect whether the page has been referenced again. But, I worry that people are going to start doing things like read NUMA, SPARSEMEM, or other internal information out of these.
I've seen quite a few patches lately that do creative things with these *cough*clameter*cough*, and I worry that they're too fluid to get exposed to userspace.
Could we just have /proc/kpagereferenced? Is there a legitimate need for other flags to be visible?
-- Dave
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