From 47dd924508f5fb10480afc69de04539fa3d14034 Mon Sep 17 00:00:00 2001 From: Andrea Arcangeli Date: Wed, 22 Feb 2017 15:43:58 -0800 Subject: [PATCH] userfaultfd: hugetlbfs: UFFD_FEATURE_MISSING_SHMEM Userland developers asked to be notified immediately by the UFFDIO_API ioctl if shmem missing mode is supported by userfaultfd in the running kernel. This avoids the need to run UFFDIO_REGISTER on a shmem virtual memory range to find out. Link: http://lkml.kernel.org/r/20161216144821.5183-38-aarcange@redhat.com Signed-off-by: Andrea Arcangeli Cc: "Dr. David Alan Gilbert" Cc: Hillf Danton Cc: Michael Rapoport Cc: Mike Kravetz Cc: Mike Rapoport Cc: Pavel Emelyanov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/uapi/linux/userfaultfd.h | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h index 10631a4..9ac4b68 100644 --- a/include/uapi/linux/userfaultfd.h +++ b/include/uapi/linux/userfaultfd.h @@ -21,7 +21,8 @@ #define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_FORK | \ UFFD_FEATURE_EVENT_REMAP | \ UFFD_FEATURE_EVENT_MADVDONTNEED | \ - UFFD_FEATURE_MISSING_HUGETLBFS) + UFFD_FEATURE_MISSING_HUGETLBFS | \ + UFFD_FEATURE_MISSING_SHMEM) #define UFFD_API_IOCTLS \ ((__u64)1 << _UFFDIO_REGISTER | \ (__u64)1 << _UFFDIO_UNREGISTER | \ @@ -146,12 +147,17 @@ struct uffdio_api { * it, so userland can later check if the feature flag is * present in uffdio_api.features after UFFDIO_API * succeeded. + * + * UFFD_FEATURE_MISSING_SHMEM works the same as + * UFFD_FEATURE_MISSING_HUGETLBFS, but it applies to shmem + * (i.e. tmpfs and other shmem based APIs). */ #define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0) #define UFFD_FEATURE_EVENT_FORK (1<<1) #define UFFD_FEATURE_EVENT_REMAP (1<<2) #define UFFD_FEATURE_EVENT_MADVDONTNEED (1<<3) #define UFFD_FEATURE_MISSING_HUGETLBFS (1<<4) +#define UFFD_FEATURE_MISSING_SHMEM (1<<5) __u64 features; __u64 ioctls; -- 2.7.4