Re: [PATCH 3/8] arch: uapi: asm: mman.h: Let MADV_FREE have same value for all architectures

On Sun, Nov 01, 2015 at 04:08:27PM -0800, Hugh Dickins wrote:

On Fri, 30 Oct 2015, Minchan Kim wrote:

quoted

From: Chen Gang <redacted>

For uapi, need try to let all macros have same value, and MADV_FREE is
added into main branch recently, so need redefine MADV_FREE for it.

At present, '8' can be shared with all architectures, so redefine it to
'8'.

Cc: rth@twiddle.net <redacted>,
Cc: ink@jurassic.park.msu.ru <redacted>
Cc: mattst88@gmail.com <mattst88@gmail.com>
Cc: Ralf Baechle <redacted>
Cc: jejb@parisc-linux.org <redacted>
Cc: deller@gmx.de <deller@gmx.de>
Cc: chris@zankel.net <chris@zankel.net>
Cc: jcmvbkbc@gmail.com <jcmvbkbc@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-api@vger.kernel.org
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Chen Gang <redacted>

Let me add
Acked-by: Hugh Dickins <hughd@google.com>
to this one too.

But I have extended your mail's Cc list: Darrick pointed out earlier
that dietlibc has a Solaris #define MADV_FREE 0x5 in its mman.h,
and that was in the kernel's sparc mman.h up until 2.6.25.  I doubt
that presents any obstacle nowadays, but Dave Miller should be Cc'ed.

I was a little suspicious that 8 is available for MADV_FREE: why did
the common/generic parameters start at 9 instead of 8 back in 2.6.16?
I think the answer is that we had MADV_REMOVE coming in from one
direction, and MADV_DONTFORK coming from another direction, and when
Roland looked for where to start the commons for MADV_DONTFORK, it
appeared that 8 was occupied - by MADV_REMOVE; then a little later
MADV_REMOVE was shifted to become the first of the commons, at 9.

Thanks for Ack, Ccing relevant people and history!