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Mike Rapoport
897ab3e0c4
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. [[email protected]: fix nommu build] Link: http://lkml.kernel.org/r/[email protected] [[email protected]: fix nommu build] Link: http://lkml.kernel.org/r/[email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Mike Rapoport <[email protected]> Signed-off-by: Michal Hocko <[email protected]> Signed-off-by: Arnd Bergmann <[email protected]> Acked-by: Hillf Danton <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: "Dr. David Alan Gilbert" <[email protected]> Cc: Mike Kravetz <[email protected]> Cc: Pavel Emelyanov <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>