CC: linux-mm On 09/15/2017 02:43 PM, Mike Kravetz wrote: > hugetlbfs support for memfd_create was recently merged by Linus and > should be in the Linux 4.14 release. To request hugetlbfs support > a new memfd_create flag (MFD_HUGETLB) was added. > > This patch documents the following commit: > > commit 749df87bd7bee5a79cef073f5d032ddb2b211de8 > Author: Mike Kravetz <mike.kravetz@xxxxxxxxxx> > Date: Wed Sep 6 16:24:16 2017 -0700 > > mm/shmem: add hugetlbfs support to memfd_create() > > Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> > --- > man2/memfd_create.2 | 27 +++++++++++++++++++++++++++ > 1 file changed, 27 insertions(+) > > diff --git a/man2/memfd_create.2 b/man2/memfd_create.2 > index 4dfd1bb2d..b61254bb8 100644 > --- a/man2/memfd_create.2 > +++ b/man2/memfd_create.2 > @@ -100,6 +100,33 @@ If this flag is not set, the initial set of seals will be > meaning that no other seals can be set on the file. > .\" FIXME Why is the MFD_ALLOW_SEALING behavior not simply the default? > .\" Is it worth adding some text explaining this? > +.TP > +.BR MFD_HUGETLB " (since Linux 4.14)" > +The anonymous file will be created in the hugetlbfs filesystem using > +huge pages. See the Linux kernel source file > +.I Documentation/vm/hugetlbpage.txt > +for more information about hugetlbfs. The hugetlbfs filesystem does > +not support file sealing operations. Therefore, specifying both > +.B MFD_HUGETLB > +and > +.B MFD_ALLOW_SEALING > +will result in an error > +.RB (EINVAL) > +being returned. > + > +.TP > +.BR MFD_HUGE_2MB ", " MFD_HUGE_1GB ", " "..." > +Used in conjunction with > +.B MFD_HUGETLB > +to select alternative hugetlb page sizes (respectively, 2 MB, 1 GB, ...) > +on systems that support multiple hugetlb page sizes. Definitions for known > +huge page sizes are included in the header file > +.I <sys/memfd.h>. > + > +For details on encoding huge page sizes not included in the header file, > +see the discussion of the similarly named constants in > +.BR mmap (2). > + > .PP > Unused bits in > .I flags > -- 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>
