Signed-off-by: Jan Kara <[email protected]>
---
man2/mmap.2 | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/man2/mmap.2 b/man2/mmap.2
index 47c3148653be..598ff0c64f7f 100644
--- a/man2/mmap.2
+++ b/man2/mmap.2
@@ -125,6 +125,21 @@ are carried through to the underlying file.
to the underlying file requires the use of
.BR msync (2).)
.TP
+.B MAP_SHARED_VALIDATE
+The same as
+.B MAP_SHARED
+except that
+.B MAP_SHARED
+mappings ignore unknown flags in
+.IR flags .
+In contrast when creating mapping of
+.B MAP_SHARED_VALIDATE
+mapping type, the kernel verifies all passed flags are known and fails the
+mapping with
+.BR EOPNOTSUPP
+otherwise. This mapping type is also required to be able to use some mapping
+flags.
+.TP
.B MAP_PRIVATE
Create a private copy-on-write mapping.
Updates to the mapping are not visible to other processes
@@ -352,6 +367,21 @@ option.
Because of the security implications,
that option is normally enabled only on embedded devices
(i.e., devices where one has complete control of the contents of user memory).
+.TP
+.BR MAP_SYNC " (since Linux 4.15)"
+This flags is available only with
+.B MAP_SHARED_VALIDATE
+mapping type. Mappings of
+.B MAP_SHARED
+type will silently ignore this flag.
+This flag is supported only for files supporting DAX (direct mapping of persistent
+memory). For other files, creating mapping with this flag results in
+.B EOPNOTSUPP
+error. Shared file mappings with this flag provide the guarantee that while
+some memory is writeably mapped in the address space of the process, it will
+be visible in the same file at the same offset even after the system crashes or
+is rebooted. This allows users of such mappings to make data modifications
+persistent in a more efficient way using appropriate CPU instructions.
.PP
Of the above flags, only
.B MAP_FIXED
--
2.12.3
On Tue, Oct 24, 2017 at 05:24:15PM +0200, Jan Kara wrote:
> Signed-off-by: Jan Kara <[email protected]>
This looks unchanged since the previous version?
> ---
> man2/mmap.2 | 30 ++++++++++++++++++++++++++++++
> 1 file changed, 30 insertions(+)
>
> diff --git a/man2/mmap.2 b/man2/mmap.2
> index 47c3148653be..598ff0c64f7f 100644
> --- a/man2/mmap.2
> +++ b/man2/mmap.2
> @@ -125,6 +125,21 @@ are carried through to the underlying file.
> to the underlying file requires the use of
> .BR msync (2).)
> .TP
> +.B MAP_SHARED_VALIDATE
> +The same as
> +.B MAP_SHARED
> +except that
> +.B MAP_SHARED
> +mappings ignore unknown flags in
> +.IR flags .
> +In contrast when creating mapping of
> +.B MAP_SHARED_VALIDATE
> +mapping type, the kernel verifies all passed flags are known and fails the
> +mapping with
> +.BR EOPNOTSUPP
> +otherwise. This mapping type is also required to be able to use some mapping
> +flags.
> +.TP
> .B MAP_PRIVATE
> Create a private copy-on-write mapping.
> Updates to the mapping are not visible to other processes
> @@ -352,6 +367,21 @@ option.
> Because of the security implications,
> that option is normally enabled only on embedded devices
> (i.e., devices where one has complete control of the contents of user memory).
> +.TP
> +.BR MAP_SYNC " (since Linux 4.15)"
> +This flags is available only with
> +.B MAP_SHARED_VALIDATE
> +mapping type. Mappings of
> +.B MAP_SHARED
> +type will silently ignore this flag.
> +This flag is supported only for files supporting DAX (direct mapping of persistent
> +memory). For other files, creating mapping with this flag results in
> +.B EOPNOTSUPP
> +error. Shared file mappings with this flag provide the guarantee that while
> +some memory is writeably mapped in the address space of the process, it will
> +be visible in the same file at the same offset even after the system crashes or
> +is rebooted. This allows users of such mappings to make data modifications
> +persistent in a more efficient way using appropriate CPU instructions.
> .PP
> Of the above flags, only
> .B MAP_FIXED
> --
> 2.12.3
>
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On Tue 24-10-17 15:10:07, Ross Zwisler wrote:
> On Tue, Oct 24, 2017 at 05:24:15PM +0200, Jan Kara wrote:
> > Signed-off-by: Jan Kara <[email protected]>
>
> This looks unchanged since the previous version?
Ah, thanks for checking. I forgot to commit modifications. Attached is
really updated patch.
Honza
--
Jan Kara <[email protected]>
SUSE Labs, CR
On Thu, Oct 26, 2017 at 03:24:02PM +0200, Jan Kara wrote:
> On Tue 24-10-17 15:10:07, Ross Zwisler wrote:
> > On Tue, Oct 24, 2017 at 05:24:15PM +0200, Jan Kara wrote:
> > > Signed-off-by: Jan Kara <[email protected]>
> >
> > This looks unchanged since the previous version?
>
> Ah, thanks for checking. I forgot to commit modifications. Attached is
> really updated patch.
>
> Honza
> --
> Jan Kara <jack-IBi9RG/[email protected]>
> SUSE Labs, CR
> From 59eeec2998ed9b3840aab951f213148cb1d053a5 Mon Sep 17 00:00:00 2001
> From: Jan Kara <[email protected]>
> Date: Thu, 19 Oct 2017 14:44:55 +0200
> Subject: [PATCH] mmap.2: Add description of MAP_SHARED_VALIDATE and MAP_SYNC
>
> Signed-off-by: Jan Kara <[email protected]>
Looks good, you can add:
Reviewed-by: Ross Zwisler <ross.zwisler-VuQAYsv1563Yd54FQh9/[email protected]>