From: Bruce Merry <bmerry@ska.ac.za>
To: linux-man@vger.kernel.org, Alejandro Colomar <alx.manpages@gmail.com>
Cc: linux-mm@kvack.org
Subject: [patch] Clarify that MAP_POPULATE is best-effort
Date: Tue, 23 Mar 2021 09:48:31 +0200 [thread overview]
Message-ID: <20210323074831.GA7535@kryton.kat.ac.za> (raw)
As discussed on linux-mm
(https://marc.info/?l=linux-mm&m=161528594100612&w=2), MAP_POPULATE can
fail silently if the hugetlb cgroup settings allow huge page reservation
but prevents huge pages being allocated.
Closes https://bugzilla.kernel.org/show_bug.cgi?id=212153.
---
man2/mmap.2 | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/man2/mmap.2 b/man2/mmap.2
index 164ba196e..03f2eeb2c 100644
--- a/man2/mmap.2
+++ b/man2/mmap.2
@@ -400,6 +400,11 @@ private writable mappings.
Populate (prefault) page tables for a mapping.
For a file mapping, this causes read-ahead on the file.
This will help to reduce blocking on page faults later.
+The
+.BR mmap ()
+call doesn't fail if the mapping cannot be populated (for example, due
+to limitations on the number of mapped huge pages when using
+.BR MAP_HUGETLB ).
.BR MAP_POPULATE
is supported for private mappings only since Linux 2.6.23.
.TP
--
2.25.1
next reply other threads:[~2021-03-23 7:49 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-23 7:48 Bruce Merry [this message]
2021-04-04 19:28 ` Michael Kerrisk (man-pages)
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