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You're opening the kernel up to being exploited > by any application which can persuade it to set this flag on a VMA. > No No this is not an application accessible flag this can only be set by the mmap implementor at ->mmap() time (Say same as VM_VM_MIXEDMAP). Please see the zuf patches for usage (Again apologise for pushing before a user) The mmap provider has all the facilities to know that this can not be abused, not even by a trusted Server. >> NOTE: This vma (VM_LOCAL_CPU) is never used during a page_fault. It is >> always used in a synchronous way from a thread pinned to a single core. > > It's not a question of how your app is going to use this flag. It's a > question about how another app can abuse this flag (or how your app is > going to be exploited to abuse this flag) to break into the kernel. > If you look at the zuf user you will see that the faults all return SIG_BUS. These can never fault. The server has access to this mapping from a single thread pinned to a core. Again it is not an app visible flag in anyway Thanks for looking Boaz