Messages in this thread | | | Date | Wed, 30 Oct 2019 11:04:18 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH RFC] mm: add MAP_EXCLUSIVE to create exclusive user mappings |
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On Tue, Oct 29, 2019 at 05:27:43PM +0000, Edgecombe, Rick P wrote: > On Mon, 2019-10-28 at 22:00 +0100, Peter Zijlstra wrote:
> > That should be limited to the module range. Random data maps could > > shatter the world. > > BPF has one vmalloc space allocation for the byte code and one for the module > space allocation for the JIT. Both get RO also set on the direct map alias of > the pages, and reset RW when freed.
Argh, I didn't know they mapped the bytecode RO; why does it do that? It can throw out the bytecode once it's JIT'ed.
> You mean shatter performance?
Shatter (all) large pages.
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