On Fri, 27 Jan 2017 20:44:30 +0200 Mike Rapoport <r...@linux.vnet.ibm.com> wrote:
> When a non-cooperative userfaultfd monitor copies pages in the background, > it may encounter regions that were already unmapped. Addition of > UFFD_EVENT_UNMAP allows the uffd monitor to track precisely changes in the > virtual memory layout. > > Since there might be different uffd contexts for the affected VMAs, we > first should create a temporary representation for the unmap event for each > uffd context and then notify them one by one to the appropriate userfault > file descriptors. > > The event notification occurs after the mmap_sem has been released. I was going to bug you about not updating Documentation/vm/userfaultfd.txt but the UFFD_FEATURE flags aren't documented?
