The shmem/hugetlbfs memory types are supported for write-protection messages very lately. Update the man page to reflect that. Signed-off-by: Peter Xu <peterx@xxxxxxxxxx> --- man2/userfaultfd.2 | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2 index 6b9412aaf..9b5ec0358 100644 --- a/man2/userfaultfd.2 +++ b/man2/userfaultfd.2 @@ -270,13 +270,18 @@ Since Linux 4.11, userfaultfd can be also used with hugetlbfs and shared memory mappings. .\" .SS Userfaultfd write-protect mode (since 5.7) -Since Linux 5.7, userfaultfd supports write-protect mode. +Since Linux 5.7, userfaultfd supports write-protect mode for anonymous memory. The user needs to first check availability of this feature using .B UFFDIO_API ioctl against the feature bit .B UFFD_FEATURE_PAGEFAULT_FLAG_WP before using this feature. .PP +Since Linux 5.19, the write-protection mode was also supported on shmem and hugetlbfs +memory types. +It can be detected with the feature bit +.BR UFFD_FEATURE_WP_HUGETLBFS_SHMEM . +.PP To register with userfaultfd write-protect mode, the user needs to initiate the .B UFFDIO_REGISTER ioctl with mode @@ -327,8 +332,6 @@ ioctl, whose should have the flag .B UFFDIO_WRITEPROTECT_MODE_WP cleared upon the faulted page or range. -.PP -Write-protect mode supports only private anonymous memory. .\" .SS Userfaultfd minor fault mode (since 5.13) Since Linux 5.13, -- 2.32.0
