[patch] memfd_create.2: Add description of MFD_HUGETLB (hugetlbfs) support
flat view
STALE3312d
From: Mike Kravetz <hidden>
Date: 2017-09-15 21:44:07
Also in:
linux-man, lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
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 [off-list ref]
Date: Wed Sep 6 16:24:16 2017 -0700
mm/shmem: add hugetlbfs support to memfd_create()
Signed-off-by: Mike Kravetz <redacted>
---
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
--
2.13.5
--
To unsubscribe from this list: send the line "unsubscribe linux-man" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html