>> I think this change will break the case where userspace tries to >> register an MR with read-only permission, but intends locally through >> the CPU to write to the memory.
> Shouldn't it set LOCAL_WRITE then? We're talking about the permissions for the register MR operation, right? (That's what the kernel RDMA driver code that does get_user_pages() sees) In that case, no, I don't see any reason for LOCAL_WRITE, since the only RDMA operations that will access this memory are remote reads. The writing (that triggers COW) is coming from normal process access triggering a page fault, etc. This is a pretty standard way of using RDMA... For example, I allocate some memory and register it for RDMA read (and pass the R_Key to the remote system) with only REMOTE_READ permission. Then I fill in the memory with the results of some computation and the remote system does an RDMA read to get those results. - R. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
