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| Started by | Mike Kravetz <mike.kravetz@oracle.com> |
|---|---|
| First post | 2017-09-15 23:50 +0200 |
| Last post | 2017-09-21 15:10 +0200 |
| Articles | 3 — 2 participants |
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[patch] memfd_create.2: Add description of MFD_HUGETLB (hugetlbfs) support Mike Kravetz <mike.kravetz@oracle.com> - 2017-09-15 23:50 +0200
Re: [patch] memfd_create.2: Add description of MFD_HUGETLB (hugetlbfs) support Mike Kravetz <mike.kravetz@oracle.com> - 2017-09-16 00:00 +0200
Re: [patch] memfd_create.2: Add description of MFD_HUGETLB (hugetlbfs) support "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2017-09-21 15:10 +0200
| From | Mike Kravetz <mike.kravetz@oracle.com> |
|---|---|
| Date | 2017-09-15 23:50 +0200 |
| Subject | [patch] memfd_create.2: Add description of MFD_HUGETLB (hugetlbfs) support |
| Message-ID | <uq6EN-h4-7@gated-at.bofh.it> |
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@oracle.com>
Date: Wed Sep 6 16:24:16 2017 -0700
mm/shmem: add hugetlbfs support to memfd_create()
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
---
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
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| From | Mike Kravetz <mike.kravetz@oracle.com> |
|---|---|
| Date | 2017-09-16 00:00 +0200 |
| Subject | Re: [patch] memfd_create.2: Add description of MFD_HUGETLB (hugetlbfs) support |
| Message-ID | <uq6Ou-lC-9@gated-at.bofh.it> |
| In reply to | #1733109 |
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@oracle.com> > Date: Wed Sep 6 16:24:16 2017 -0700 > > mm/shmem: add hugetlbfs support to memfd_create() > > Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> > --- > 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 >
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| From | "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> |
|---|---|
| Date | 2017-09-21 15:10 +0200 |
| Subject | Re: [patch] memfd_create.2: Add description of MFD_HUGETLB (hugetlbfs) support |
| Message-ID | <us9oR-1pB-1@gated-at.bofh.it> |
| In reply to | #1733109 |
Hi Mike, On 09/15/2017 11:43 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@oracle.com> > Date: Wed Sep 6 16:24:16 2017 -0700 > > mm/shmem: add hugetlbfs support to memfd_create() Thanks! I've applied this patch. Cheers, Michael > > Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> > --- > 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 > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
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