Re: [PATCH v16 07/11] secretmem: use PMD-size pages to amortize direct map fragmentation
From: David Hildenbrand <hidden>
Date: 2021-02-02 14:29:12
Also in:
linux-api, linux-arch, linux-fsdevel, linux-kselftest, linux-mm, linux-riscv, lkml, nvdimm
On 02.02.21 15:22, Michal Hocko wrote:
On Tue 02-02-21 15:12:21, David Hildenbrand wrote: [...]quoted
I think secretmem behaves much more like longterm GUP right now ("unmigratable", "lifetime controlled by user space", "cannot go on CMA/ZONE_MOVABLE"). I'd either want to reasonably well control/limit it or make it behave more like mlocked pages.I thought I have already asked but I must have forgotten. Is there any actual reason why the memory is not movable? Timing attacks?
I think the reason is simple: no direct map, no copying of memory. As I mentioned, we would have to temporarily map in order to copy. Mapping it somewhere else (like kmap), outside of the direct map might reduce possible attacks. -- Thanks, David / dhildenb _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel