madvise.2: Starting with Linux 3.5, more file systems support MADV_REMOVE

As from upstream commit:

commit 3f31d07571eeea18a7d34db9af21d2285b807a17
Author: Hugh Dickins <hughd@google.com>
Date:   Tue May 29 15:06:40 2012 -0700

     mm/fs: route MADV_REMOVE to FALLOC_FL_PUNCH_HOLE

     Now tmpfs supports hole-punching via fallocate(), switch madvise_remove()
     to use do_fallocate() instead of vmtruncate_range(): which extends
     madvise(,,MADV_REMOVE) support from tmpfs to ext4, ocfs2 and xfs.

madvise(,,MADV_REMOVE) support was extended by ext4, ocfs2 and xfs.

bug report: https://bugzilla.redhat.com/show_bug.cgi?id=1120294

Justification from Rafael Aquini:
Well, that code is committed in kernel since v3.5 (2012) and it
surely is the expected behaviour since. It seems to me that
madvise(2) man page text for MADV_REMOVE just got out-of-date in
that regard.

This patch mentions this support in madvise.2 man page.

Reworded and corrected by Michael Kerrisk and Hugh Dickins. Thank you.

Signed-off-by: Jan Chaloupka <jchaloup@redhat.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man2/madvise.2

@@ -148,11 +148,19 @@ bytes containing zero.
 .\" disk/swap space.  This feature is also useful for supporting
 .\" hot-plug memory on UML.
 
-Currently,
-.\" 2.6.18-rc5
-only shmfs/tmpfs supports this; other filesystems return with the
-error
-.BR ENOSYS .
+Originally, only shmfs/tmpfs supported this; but since Linux 3.5,
+any filesystem which supports the
+.BR fallocate(2)
+mode
+.BR FALLOC_FL_PUNCH_HOLE
+also supports the
+.BR madvise(2)
+advice
+.BR MADV_REMOVE .
+Other filesystems return with the
+.BR EOPNOTSUPP
+error.
+
 The specified address range must be mapped shared and writable.
 This flag cannot be applied to locked pages or Huge TLB pages.
 .TP