Messages in this thread | | | From | KOSAKI Motohiro <> | Subject | Re: [PATCH -mm] vmscan: make mapped executable pages the first class citizen | Date | Sat, 9 May 2009 19:20:09 +0900 (JST) |
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> On Thu, 7 May 2009, Elladan wrote: > > > > Nobody (except you) is proposing that we completely disable > > > the eviction of executable pages. I believe that your idea > > > could easily lead to a denial of service attack, with a user > > > creating a very large executable file and mmaping it. > > The amount of mlockable pages is limited via ulimit. We can already make > the pages unreclaimable through mlock(). > > > I don't know of any distro that applies default ulimits, so desktops are > > already susceptible to the far more trivial "call malloc a lot" or "fork bomb" > > attacks. Plus, ulimits don't help, since they only apply per process - you'd > > need a default mem cgroup before this mattered, I think. > > The point remains that the proposed patch does not solve the general > problem that we encounter with exec pages of critical components of the > user interface being evicted from memory. > > Do we have test data that shows a benefit? The description is minimal. Rik > claimed on IRC that tests have been done. If so then the patch description > should include the tests. Which loads benefit from this patch? > > A significant change to the reclaim algorithm also needs to > have a clear description of the effects on reclaim behavior which is also > lacking.
btw,
This is very good news to me. Recently I've taked sevaral time for reproducing this issue. but I have no luck. I'm interesting its test-case.
Thanks.
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