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 | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2 index 0928a76d2..99aae8b50 100644 --- a/man2/userfaultfd.2 +++ b/man2/userfaultfd.2 @@ -273,13 +273,17 @@ 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 @@ -330,8 +334,6 @@ 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 Reading from the userfaultfd structure Each .BR read (2) -- 2.32.0
