On Thu, Sep 27, 2018 at 12:10:03PM +0200, Arnd Bergmann wrote: > The zap_vma_ptes() is declared but not defined on NOMMU kernels, > causing a link error for the newly added uverbs code: > > drivers/infiniband/core/uverbs_main.o: In function `uverbs_user_mmap_disassociate': > uverbs_main.c:(.text+0x114c): undefined reference to `zap_vma_ptes' > drivers/infiniband/core/uverbs_main.o: In function `rdma_umap_open': > uverbs_main.c:(.text+0x53c): undefined reference to `zap_vma_ptes' I'm a bit surprised by this - the code is not new, it just got moved out of the drivers, and I don't see any protections there against CONFIG_MMU ?? > To fix this, we can either make uverbs depend on CONFIG_MMU, or try > to build it anyway. Since this is the only compile-time dependency, > I decided to allow building it with an extra compile-time check for > CONFIG_MMU before calling the one function. Hrm. So this code doesn't work at all on NOMMU, it relies on remap_pfn_range, which always fails on those kernels, Due to this of this the entirety of INFINIBAND_USER_ACCESS is broken. I think a kconfig change is the better way to go? Jason
