Messages in this thread | | | Date | Wed, 24 Nov 2021 11:34:05 -0400 | From | Jason Gunthorpe <> | Subject | Re: [PATCH] Increase default MLOCK_LIMIT to 8 MiB |
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On Wed, Nov 24, 2021 at 03:14:00PM +0100, David Hildenbrand wrote:
> I'm not aware of any where you can fragment 50% of all pageblocks in the > system as an unprivileged user essentially consuming almost no memory > and essentially staying inside well-defined memlock limits. But sure if > there are "many" people will be able to come up with at least one > comparable thing. I'll be happy to learn.
If the concern is that THP's can be DOS'd then any avenue that renders the system out of THPs is a DOS attack vector. Including all the normal workloads that people run and already complain that THPs get exhausted.
A hostile userspace can only quicken this process.
> My position that FOLL_LONGTERM for unprivileged users is a strong no-go > stands as it is.
As this basically excludes long standing pre-existing things like RDMA, XDP, io_uring, and more I don't think this can be the general answer for mm, sorry.
Sure, lets stop now since I don't think we can agree.
Jason
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