On 04/27/2017 04:14 PM, Mike Rapoport wrote: > Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> Thanks, Mike. Applied, and lightly edited. All changes now pushed to Git. Cheers, Michael > --- > man2/ioctl_userfaultfd.2 | 53 ++++++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 51 insertions(+), 2 deletions(-) > > diff --git a/man2/ioctl_userfaultfd.2 b/man2/ioctl_userfaultfd.2 > index 42bf7a7..cdc07e0 100644 > --- a/man2/ioctl_userfaultfd.2 > +++ b/man2/ioctl_userfaultfd.2 > @@ -121,22 +121,70 @@ and explicitly enable userfaultfd features that are disabled by default. > The kernel always reports all the available features in the > .I features > field. > + > +To enable userfaultfd features the application should set > +a bit corresponding to each feature it wants to enable in the > +.I features > +field. > +If the kernel supports all the requested features it will enable them. > +Otherwise it will zero out the returned > +.I uffdio_api > +structure and return > +.BR EINVAL . > .\" FIXME add more details about feature negotiation and enablement > > Since Linux 4.11, the following feature bits may be set: > .TP > .B UFFD_FEATURE_EVENT_FORK > +When this feature is enabled, > +the userfaultfd objects associated with a parent process are duplicated > +into the child process during > +.BR fork (2) > +system call and the > +.I UFFD_EVENT_FORK > +is delivered to the userfaultfd monitor > .TP > .B UFFD_FEATURE_EVENT_REMAP > +If this feature is enabled, > +when the faulting process invokes > +.BR mremap (2) > +system call > +the userfaultfd monitor will receive an event of type > +.I UFFD_EVENT_REMAP. > .TP > .B UFFD_FEATURE_EVENT_REMOVE > +If this feature is enabled, > +when the faulting process calls > +.BR madvise(2) > +system call with > +.I MADV_DONTNEED > +or > +.I MADV_REMOVE > +advice to free a virtual memory area > +the userfaultfd monitor will receive an event of type > +.I UFFD_EVENT_REMOVE. > .TP > .B UFFD_FEATURE_EVENT_UNMAP > +If this feature is enabled, > +when the faulting process unmaps virtual memory either explicitly with > +.BR munmap (2) > +system call, or implicitly either during > +.BR mmap (2) > +or > +.BR mremap (2) > +system call, > +the userfaultfd monitor will receive an event of type > +.I UFFD_EVENT_UNMAP > .TP > .B UFFD_FEATURE_MISSING_HUGETLBFS > +If this feature bit is set, > +the kernel supports registering userfaultfd ranges on hugetlbfs > +virtual memory areas > .TP > .B UFFD_FEATURE_MISSING_SHMEM > -.\" FIXME add feature description > +If this feature bit is set, > +the kernel supports registering userfaultfd ranges on tmpfs > +virtual memory areas > > The returned > .I ioctls > @@ -182,7 +230,8 @@ The API version requested in the > .I api > field is not supported by this kernel, or the > .I features > -field was not zero. > +field passed to the kernel includes feature bits that are not supported > +by the current kernel version. > .\" FIXME In the above error case, the returned 'uffdio_api' structure is > .\" zeroed out. Why is this done? This should be explained in the manual page. > .\" > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
