From: Ross Zwisler <ross.zwisler-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
To: "Michael Kerrisk (man-pages)"
<mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: xfs <linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>,
linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org,
Linux API <linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"Darrick J . Wong"
<darrick.wong-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>,
Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
Linux-MM <linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org>,
"linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Ext4 Developers List
<linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: [PATCH] mmap.2: Add description of MAP_SHARED_VALIDATE and MAP_SYNC
Date: Thu, 12 Apr 2018 08:00:59 -0600 [thread overview]
Message-ID: <20180412140059.GA7992@linux.intel.com> (raw)
In-Reply-To: <CAKgNAkhsFrcdkXNA2cw3o0gJV0uLRtBg9ybaCe5xy1QBC2PgqA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
On Thu, Apr 12, 2018 at 03:00:49PM +0200, Michael Kerrisk (man-pages) wrote:
> Hello Jan,
>
> I have applied your patch, and tweaked the text a little, and pushed
> the result to the git repo.
>
> On 1 November 2017 at 16:36, Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org> wrote:
> > Reviewed-by: Ross Zwisler <ross.zwisler-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> > Signed-off-by: Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>
>
> I have a question below.
>
> > ---
> > man2/mmap.2 | 35 ++++++++++++++++++++++++++++++++++-
> > 1 file changed, 34 insertions(+), 1 deletion(-)
> >
> > diff --git a/man2/mmap.2 b/man2/mmap.2
> > index 47c3148653be..b38ee6809327 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
> > +.BR MAP_SHARED_VALIDATE " (since Linux 4.15)"
> > +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
> > @@ -134,7 +149,10 @@ It is unspecified whether changes made to the file after the
> > .BR mmap ()
> > call are visible in the mapped region.
> > .PP
> > -Both of these flags are described in POSIX.1-2001 and POSIX.1-2008.
> > +.B MAP_SHARED
> > +and
> > +.B MAP_PRIVATE
> > +are described in POSIX.1-2001 and POSIX.1-2008.
> > .PP
> > In addition, zero or more of the following values can be ORed in
> > .IR flags :
> > @@ -352,6 +370,21 @@ 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.
>
> It feels like there's a word missing/unclear wording in the previous
> line, before "using". Without that word, the sentence feels a bit
> ambiguous.
>
> Should it be:
>
> persistent in a more efficient way *through the use of* appropriate
> CPU instructions.
>
> or:
>
> persistent in a more efficient way *than using* appropriate CPU instructions.
>
> ?
>
> Is suspect the first is correct, but need to check.
You're right, the first one is correct.
next prev parent reply other threads:[~2018-04-12 14:00 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-01 15:36 [PATCH 0/18 v6] dax, ext4, xfs: Synchronous page faults Jan Kara
2017-11-01 15:36 ` [PATCH 02/18] mm: Remove VM_FAULT_HWPOISON_LARGE_MASK Jan Kara
2017-11-01 15:36 ` [PATCH 04/18] dax: Factor out getting of pfn out of iomap Jan Kara
[not found] ` <20171101153648.30166-1-jack-AlSwsSmVLrQ@public.gmane.org>
2017-11-01 15:36 ` [PATCH 01/18] mm: introduce MAP_SHARED_VALIDATE, a mechanism to safely define new mmap flags Jan Kara
[not found] ` <20171101153648.30166-2-jack-AlSwsSmVLrQ@public.gmane.org>
2017-11-22 12:02 ` Vlastimil Babka
2017-11-22 16:52 ` Dan Williams
[not found] ` <CAPcyv4gGRHWc6AH5Enb7njtmqHgd=g+0-mYMdd5wWjJMW0+d7g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-11-22 19:53 ` Matthew Wilcox
2017-11-25 18:45 ` Helge Deller
2017-11-27 15:55 ` Vlastimil Babka
2017-11-01 15:36 ` [PATCH 03/18] dax: Simplify arguments of dax_insert_mapping() Jan Kara
2017-11-01 15:36 ` [PATCH 05/18] dax: Create local variable for VMA in dax_iomap_pte_fault() Jan Kara
2017-11-01 15:36 ` [PATCH 06/18] dax: Create local variable for vmf->flags & FAULT_FLAG_WRITE test Jan Kara
2017-11-01 15:36 ` [PATCH 07/18] dax: Inline dax_insert_mapping() into the callsite Jan Kara
2017-11-01 15:36 ` [PATCH 09/18] dax: Fix comment describing dax_iomap_fault() Jan Kara
2017-11-01 15:36 ` [PATCH 10/18] dax: Allow dax_iomap_fault() to return pfn Jan Kara
2017-11-01 15:36 ` [PATCH 11/18] dax: Allow tuning whether dax_insert_mapping_entry() dirties entry Jan Kara
2017-11-01 15:36 ` [PATCH 12/18] mm: Define MAP_SYNC and VM_SYNC flags Jan Kara
2017-11-01 15:36 ` [PATCH 13/18] dax, iomap: Add support for synchronous faults Jan Kara
2017-11-01 15:36 ` [PATCH 14/18] dax: Implement dax_finish_sync_fault() Jan Kara
2017-11-01 15:36 ` [PATCH 15/18] ext4: Simplify error handling in ext4_dax_huge_fault() Jan Kara
2017-11-01 15:36 ` [PATCH 16/18] ext4: Support for synchronous DAX faults Jan Kara
2017-11-01 15:36 ` [PATCH 17/18] xfs: Implement xfs_filemap_pfn_mkwrite() using __xfs_filemap_fault() Jan Kara
[not found] ` <20171101153648.30166-18-jack-AlSwsSmVLrQ@public.gmane.org>
2017-11-14 2:19 ` Darrick J. Wong
2017-11-01 15:36 ` [PATCH 18/18] xfs: support for synchronous DAX faults Jan Kara
2017-11-14 2:19 ` Darrick J. Wong
2017-11-01 15:36 ` [PATCH] mmap.2: Add description of MAP_SHARED_VALIDATE and MAP_SYNC Jan Kara
[not found] ` <20171101153648.30166-20-jack-AlSwsSmVLrQ@public.gmane.org>
2018-04-12 13:00 ` Michael Kerrisk (man-pages)
[not found] ` <CAKgNAkhsFrcdkXNA2cw3o0gJV0uLRtBg9ybaCe5xy1QBC2PgqA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-04-12 14:00 ` Ross Zwisler [this message]
2018-04-12 14:22 ` Jan Kara
[not found] ` <20180412142214.fcxw3g2jxv6bvn7d-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2018-04-12 18:20 ` Michael Kerrisk (man-pages)
[not found] ` <CAKgNAkgtVryFb81QgzwPq8SD241yKDN1xNxOWUUQH9QBYV13SA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-04-13 11:17 ` Jan Kara
2017-11-01 15:36 ` [PATCH 08/18] dax: Inline dax_pmd_insert_mapping() into the callsite Jan Kara
-- strict thread matches above, loose matches on Subject: below --
2017-10-24 15:23 [PATCH 0/17 v5] dax, ext4, xfs: Synchronous page faults Jan Kara
[not found] ` <20171024152415.22864-1-jack-AlSwsSmVLrQ@public.gmane.org>
2017-10-24 15:24 ` [PATCH] mmap.2: Add description of MAP_SHARED_VALIDATE and MAP_SYNC Jan Kara
2017-10-24 21:10 ` Ross Zwisler
2017-10-26 13:24 ` Jan Kara
[not found] ` <20171026132402.GB31161-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2017-10-26 18:22 ` Ross Zwisler
2017-10-19 12:57 [PATCH 0/17 v4] dax, ext4, xfs: Synchronous page faults Jan Kara
[not found] ` <20171019125817.11580-1-jack-AlSwsSmVLrQ@public.gmane.org>
2017-10-19 12:58 ` [PATCH] mmap.2: Add description of MAP_SHARED_VALIDATE and MAP_SYNC Jan Kara
[not found] ` <20171019125817.11580-19-jack-AlSwsSmVLrQ@public.gmane.org>
2017-10-20 21:47 ` Ross Zwisler
[not found] ` <20171020214753.GA15733-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-10-24 13:27 ` Jan Kara
[not found] ` <20171024132713.GD8556-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2017-10-24 14:55 ` Ross Zwisler
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180412140059.GA7992@linux.intel.com \
--to=ross.zwisler-vuqaysv1563yd54fqh9/ca@public.gmane.org \
--cc=darrick.wong-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org \
--cc=hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org \
--cc=jack-AlSwsSmVLrQ@public.gmane.org \
--cc=linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org \
--cc=linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org \
--cc=linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).