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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.

Andrea Arcangeli committed 9 years ago

Commit 47dd9241 parent cb658a41 file · +7 −1Browse files

Showing the changes to include/uapi/linux (1 of 1 file). Show all

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include/uapi/linux/userfaultfd.h+7−1
@@ -21,7 +21,8 @@ · 20 unmodified lines
21#define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_FORK | \21#define UFFD_API_FEATURES (UFFD_FEATURE_EVENT_FORK | \
22 UFFD_FEATURE_EVENT_REMAP | \22 UFFD_FEATURE_EVENT_REMAP | \
23 UFFD_FEATURE_EVENT_MADVDONTNEED | \23 UFFD_FEATURE_EVENT_MADVDONTNEED | \
24 UFFD_FEATURE_MISSING_HUGETLBFS)24 UFFD_FEATURE_MISSING_HUGETLBFS | \
25 UFFD_FEATURE_MISSING_SHMEM)
25#define UFFD_API_IOCTLS \26#define UFFD_API_IOCTLS \
26 ((__u64)1 << _UFFDIO_REGISTER | \27 ((__u64)1 << _UFFDIO_REGISTER | \
27 (__u64)1 << _UFFDIO_UNREGISTER | \28 (__u64)1 << _UFFDIO_UNREGISTER | \
@@ -146,12 +147,17 @@ struct uffdio_api { · 118 unmodified lines
146 * it, so userland can later check if the feature flag is147 * it, so userland can later check if the feature flag is
147 * present in uffdio_api.features after UFFDIO_API148 * present in uffdio_api.features after UFFDIO_API
148 * succeeded.149 * succeeded.
150 *
151 * UFFD_FEATURE_MISSING_SHMEM works the same as
152 * UFFD_FEATURE_MISSING_HUGETLBFS, but it applies to shmem
153 * (i.e. tmpfs and other shmem based APIs).
149 */154 */
150#define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0)155#define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0)
151#define UFFD_FEATURE_EVENT_FORK (1<<1)156#define UFFD_FEATURE_EVENT_FORK (1<<1)
152#define UFFD_FEATURE_EVENT_REMAP (1<<2)157#define UFFD_FEATURE_EVENT_REMAP (1<<2)
153#define UFFD_FEATURE_EVENT_MADVDONTNEED (1<<3)158#define UFFD_FEATURE_EVENT_MADVDONTNEED (1<<3)
154#define UFFD_FEATURE_MISSING_HUGETLBFS (1<<4)159#define UFFD_FEATURE_MISSING_HUGETLBFS (1<<4)
160#define UFFD_FEATURE_MISSING_SHMEM (1<<5)
155 __u64 features;161 __u64 features;
156 162
157 __u64 ioctls;163 __u64 ioctls;