On Mon, Sep 03, 2018 at 05:28:43PM -0700, Andrew Morton wrote: > > > I'm beginning to feel vm_fault_t exhaustion. Please remind me what > > > benefit we're going to get out of all this churn? Hi Andrew, The primary benefit is to help driver writers. At the moment, there is nothing to stop them returning -ENOMEM instead of VM_FAULT_NOMEM. There were one or two examples of this in the tree, but I think they're all gone now. Secondarily, there are a number of places which translate between error codes and vm_fault codes. Those places are reduced as a result of these patches, if not entirely eliminated yet. There was some pretty extreme cargo-culting of errno to vm_fault switch statements, particularly in the DRM drivers. There were also several places which were just ignoring the return value of vm_insert_foo(), and as a result of this audit, those have been fixed. Those errors are going to be rare, but can cause inappropriate decisions to be made by the OOM killer. Now that I think about it, vmf_insert_foo() should probably get marked with __must_check to prevent those kinds of errors from being introduced again.
