[PATCH] mremap.2: Add note about mremap with locked areas

[Eric B Munson]

When mremap() is used to move or expand a mapping that is locked with
mlock() or equivalent it will attempt to populate the new area.
However, like mmap(MAP_LOCKED), mremap() will not fail if the area
cannot be populated.  Also like mmap(MAP_LOCKED) this might come as a
surprise to users and should be noted.

Signed-off-by: Eric B Munson <emunson@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: linux-man@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 man2/mremap.2 | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/man2/mremap.2 b/man2/mremap.2
index 071adb5..cf884e6 100644
--- a/man2/mremap.2
+++ b/man2/mremap.2
@@ -196,6 +196,17 @@ and the prototype for
 did not allow for the
 .I new_address
 argument.
+
+If
+.BR mremap ()
+is used to move or expand an area locked with
+.BR mlock (2)
+or equivalent, the
+.BR mremap ()
+call will make a best effort to populate the new area but will not fail
+with
+.B ENOMEM
+if the area cannot be populated.
 .SH SEE ALSO
 .BR brk (2),
 .BR getpagesize (2),
-- 
1.9.1

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