From: Brian Geffon <bgeffon@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Michael S . Tsirkin" <mst@redhat.com>,
Brian Geffon <bgeffon@google.com>, Arnd Bergmann <arnd@arndb.de>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-api@vger.kernel.org, Andy Lutomirski <luto@amacapital.net>,
Will Deacon <will@kernel.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Sonny Rao <sonnyrao@google.com>, Minchan Kim <minchan@kernel.org>,
Joel Fernandes <joel@joelfernandes.org>,
Yu Zhao <yuzhao@google.com>, Jesse Barnes <jsbarnes@google.com>,
Nathan Chancellor <natechancellor@gmail.com>,
Florian Weimer <fweimer@redhat.com>,
"Kirill A . Shutemov" <kirill@shutemov.name>
Subject: [PATCH] mremap.2: Add information for MREMAP_DONTUNMAP.
Date: Fri, 7 Feb 2020 12:21:24 -0800 [thread overview]
Message-ID: <20200207202124.68949-1-bgeffon@google.com> (raw)
In-Reply-To: <20200207201856.46070-1-bgeffon@google.com>
Signed-off-by: Brian Geffon <bgeffon@google.com>
---
man2/mremap.2 | 27 ++++++++++++++++++++++++++-
1 file changed, 26 insertions(+), 1 deletion(-)
diff --git a/man2/mremap.2 b/man2/mremap.2
index d73fb64fa..c660a45be 100644
--- a/man2/mremap.2
+++ b/man2/mremap.2
@@ -26,7 +26,8 @@
.\" 1996-04-12 Tom Bjorkholm <tomb@mydata.se>
.\" Update for Linux 1.3.87 and later
.\" 2005-10-11 mtk: Added NOTES for MREMAP_FIXED; revised EINVAL text.
-.\"
+.\" 2020-02-05 Brian Geffon <bgeffon@google.com>
+.\" Update for MREMAP_DONTUNMAP.
.TH MREMAP 2 2019-03-06 "Linux" "Linux Programmer's Manual"
.SH NAME
mremap \- remap a virtual memory address
@@ -129,6 +130,13 @@ If
is specified, then
.B MREMAP_MAYMOVE
must also be specified.
+.TP
+.BR MREMAP_DONTUNMAP " (since Linux ?.?)"
+This flag which must be used in conjuction with
+.B MREMAP_MAYMOVE
+remaps a mapping to a new address and it does not unmap the mapping at \fIold_address\fP. This flag can only be used with private anonymous mappings. Any access to the range specified at \fIold_address\fP after completion will result in a page fault. If a
+.BR userfaultfd (2)
+was registered on the mapping specified by \fIold_address\fP it will continue to watch that mapping for faults.
.PP
If the memory segment specified by
.I old_address
@@ -176,6 +184,8 @@ a value other than
.B MREMAP_MAYMOVE
or
.B MREMAP_FIXED
+or
+.B MREMAP_DONTUNMAP
was specified in
.IR flags ;
.IP *
@@ -197,9 +207,14 @@ and
.IR old_size ;
.IP *
.B MREMAP_FIXED
+or
+.B MREMAP_DONTUNMAP
was specified without also specifying
.BR MREMAP_MAYMOVE ;
.IP *
+.B MREMAP_DONTUNMAP
+was specified with an \fIold_address\fP that was not private anonymous;
+.IP *
\fIold_size\fP was zero and \fIold_address\fP does not refer to a
shareable mapping (but see BUGS);
.IP *
@@ -209,10 +224,20 @@ flag was not specified.
.RE
.TP
.B ENOMEM
+Not enough memory was available to complete the operation.
+Possible causes are:
+.RS
+.IP * 3
The memory area cannot be expanded at the current virtual address, and the
.B MREMAP_MAYMOVE
flag is not set in \fIflags\fP.
Or, there is not enough (virtual) memory available.
+.IP *
+.B MREMAP_DONTUNMAP
+was used without
+.B MREMAP_FIXED
+causing a new mapping to be created that would exceed the virtual memory available or it would exceed the maximum number of allowed mappings.
+.RE
.SH CONFORMING TO
This call is Linux-specific, and should not be used in programs
intended to be portable.
--
2.25.0.341.g760bfbb309-goog
next prev parent reply other threads:[~2020-02-07 20:21 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-07 20:18 [PATCH v4] mm: Add MREMAP_DONTUNMAP to mremap() Brian Geffon
2020-02-07 20:18 ` Brian Geffon
2020-02-07 20:21 ` Brian Geffon [this message]
2020-02-07 20:21 ` [PATCH] mremap.2: Add information for MREMAP_DONTUNMAP Brian Geffon
2020-02-13 12:55 ` Christian Brauner
2020-02-10 1:21 ` [PATCH v4] mm: Add MREMAP_DONTUNMAP to mremap() Andrew Morton
2020-02-10 1:21 ` Andrew Morton
2020-02-10 18:38 ` Brian Geffon
2020-02-10 18:38 ` Brian Geffon
2020-02-10 18:38 ` Brian Geffon
2020-02-10 10:45 ` Kirill A. Shutemov
2020-02-10 14:12 ` Brian Geffon
2020-02-10 14:12 ` Brian Geffon
2020-02-13 12:08 ` Kirill A. Shutemov
2020-02-13 18:20 ` Brian Geffon
2020-02-13 18:20 ` Brian Geffon
2020-02-14 0:36 ` Kirill A. Shutemov
2020-02-11 23:13 ` Daniel Colascione
2020-02-11 23:13 ` Daniel Colascione
2020-02-11 23:32 ` Brian Geffon
2020-02-11 23:32 ` Brian Geffon
2020-02-11 23:32 ` Brian Geffon
2020-02-11 23:53 ` Daniel Colascione
2020-02-11 23:53 ` Daniel Colascione
2020-02-11 23:53 ` Daniel Colascione
2020-02-14 4:09 ` [PATCH v5 1/2] " Brian Geffon
2020-02-14 4:09 ` Brian Geffon
2020-02-14 4:09 ` [PATCH v5 2/2] selftest: Add MREMAP_DONTUNMAP selftest Brian Geffon
2020-02-14 4:09 ` Brian Geffon
2020-02-14 14:28 ` [PATCH v5 1/2] mm: Add MREMAP_DONTUNMAP to mremap() Kirill A. Shutemov
2020-02-14 18:46 ` Brian Geffon
2020-02-14 18:46 ` Brian Geffon
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