Thank you for the feedback Alejandro. I'm writing a revision now to
better stay in format.

Should we refer from one page to the other?  It's hard to keep in sync
two manual pages with the same text.

Do you think that keeping the more descriptive paragraph in
set_mempolicy(2) and putting a brief referral in mbind(2) would work:

MPOL_PREFERRED_MANY (since Linux 5.15)
Specifies a set of nodes for allocation; see set_mempolicy(2)


-Matt C


On Thu, Feb 20, 2025 at 6:35 AM Alejandro Colomar [off-list ref] wrote:

Hi Matthew,

quoted

Cc: linux-man@vger.kernel.org, dave.hansen@linux.intel.com

Please add a Cc tag for Dave in the trailer of the commit message.

On Tue, Feb 18, 2025 at 10:19:39AM -0600, Matthew Cassell wrote:

quoted

Browsing a header file in the kernel source and saw the memory policy enum used
for mbind() and set_mempolicy() using an entry that I didn't recognize. I man 2'd

Please use 2 spaces as the inter-sentence separation in commit messages
(in man(7) source we always break the line after period).

$ cat CONTRIBUTING.d/patches/description | sed -n '/Style/,+5p'
    Style guide
        URIs should always be enclosed in <>.

        The correct inter-sentence space amount is two.  See some
        history about this:
        <https://web.archive.org/web/20171217060354/http://www.heracliteanriver.com/?p=324>

quoted

both system calls and didn't see an entry for MPOL_PREFERRED_MANY. The commit on
the enum entry:

Commit b27abaccf8e8 ("mm/mempolicy: added MPOL_PREFERRED_MANY for multiple

Let's remove 'Commit'; it's already obvious from what follows.  Instead
it would be useful to say which repository the commit is in (and the
commit date):

linux.git b27abaccf8e8 (2021-09-03; "mm/mempolicy: add MPOL_PREFERRED_MANY for multiple preferred nodes")

Also, while in general I use a 72-column right margin for commit
messages, I think I prefer if we don't break this reference.

quoted

preferred nodes")

The commit message gives the rationale as to why the MPOL_PREFERRED_MANY mode
would be beneficial. Giving the ability to set the memory policy to target
different tiers of memory over different NUMA nodes.

Signed-off-by: Matthew Cassell <redacted>
---
 man/man2/mbind.2         | 11 +++++++++++
 man/man2/set_mempolicy.2 | 11 +++++++++++
 2 files changed, 22 insertions(+)

diff --git a/man/man2/mbind.2 b/man/man2/mbind.2
index fd1aca4ad..a5a7f4bdc 100644
--- a/man/man2/mbind.2
+++ b/man/man2/mbind.2

@@ -107,6 +107,7 @@ argument must specify one of
 .BR MPOL_INTERLEAVE ,
 .BR MPOL_WEIGHTED_INTERLEAVE ,
 .BR MPOL_PREFERRED ,
+.BR MPOL_PREFERRED_MANY ,
 or
 .B MPOL_LOCAL
 (which are described in detail below).

@@ -277,6 +278,16 @@ and
 arguments specify the empty set, then the memory is allocated on
 the node of the CPU that triggered the allocation.
 .TP
+.BR MPOL_PREFERRED_MANY " (since Linux 5.15)"
+.\" commit b27abaccf8e8b012f126da0c2a1ab32723ec8b9f
+This mode specifies a preference for nodes from which the kernel will
+try to allocate from. This differs from

Please use semantic newlines.  See man-pages(7):

$ MANWIDTH=72 man man-pages | sed -n '/Use semantic newlines/,/^$/p'
   Use semantic newlines
       In  the source of a manual page, new sentences should be started
       on new lines, long sentences  should  be  split  into  lines  at
       clause  breaks (commas, semicolons, colons, and so on), and long
       clauses should be split at phrase boundaries.  This  convention,
       sometimes  known  as "semantic newlines", makes it easier to see
       the effect of patches, which often operate at the level of indi-
       vidual sentences, clauses, or phrases.

quoted

+.BR MPOL_PREFERRED
+in that it accepts a set of nodes versus a single node. This policy
+is intended to benefit page allocations where specific memory types
+(i.e. non-volatile, high-bandwidth, or accelerator memory) are of
+greater importance than node location.
+.TP
 .BR MPOL_LOCAL " (since Linux 3.8)"
 .\" commit 479e2802d09f1e18a97262c4c6f8f17ae5884bd8
 .\" commit f2a07f40dbc603c15f8b06e6ec7f768af67b424f

diff --git a/man/man2/set_mempolicy.2 b/man/man2/set_mempolicy.2
index 2d0b1da19..f4651ccd3 100644
--- a/man/man2/set_mempolicy.2
+++ b/man/man2/set_mempolicy.2

@@ -65,6 +65,7 @@ argument must specify one of
 .BR MPOL_INTERLEAVE ,
 .BR MPOL_WEIGHTED_INTERLEAVE ,
 .BR MPOL_PREFERRED ,
+.BR MPOL_PREFERRED_MANY ,
 or
 .B MPOL_LOCAL
 (which are described in detail below).

@@ -234,6 +235,16 @@ arguments specify the empty set, then the policy
 specifies "local allocation"
 (like the system default policy discussed above).
 .TP
+.BR MPOL_PREFERRED_MANY " (since Linux 5.15)"
+.\" commit b27abaccf8e8b012f126da0c2a1ab32723ec8b9f
+This mode specifies a preference for nodes from which the kernel will
+try to allocate from. This differs from
+.BR MPOL_PREFERRED
+in that it accepts a set of nodes versus a single node. This policy
+is intended to benefit page allocations where specific memory types
+(i.e. non-volatile, high-bandwidth, or accelerator memory) are of
+greater importance than node location.

Should we refer from one page to the other?  It's hard to keep in sync
two manual pages with the same text.


Have a lovely day!
Alex

quoted

+.TP
 .BR MPOL_LOCAL " (since Linux 3.8)"
 .\" commit 479e2802d09f1e18a97262c4c6f8f17ae5884bd8
 .\" commit f2a07f40dbc603c15f8b06e6ec7f768af67b424f
--
2.39.5 (Apple Git-154)

--
<https://www.alejandro-colomar.es/>