Re: [PATCH 0/4] ipc/shm.c: increase the limits for SHMMAX, SHMALL

From: Davidlohr Bueso <davidlohr@hp.com>
To: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Cc: Manfred Spraul <manfred@colorfullife.com>,
	Davidlohr Bueso <davidlohr.bueso@hp.com>,
	Martin Schwidefsky <schwidefsky@de.ibm.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Greg Thelen <gthelen@google.com>,
	aswin@hp.com, "linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH 0/4] ipc/shm.c: increase the limits for SHMMAX, SHMALL
Date: Wed, 07 May 2014 11:22:45 -0700	[thread overview]
Message-ID: <1399486965.4567.9.camel@buesod1.americas.hpqcorp.net> (raw)
In-Reply-To: <5369C43D.1000206@gmail.com>

On Wed, 2014-05-07 at 07:27 +0200, Michael Kerrisk (man-pages) wrote:
> On 05/07/2014 12:08 AM, Davidlohr Bueso wrote:
> > On Tue, 2014-05-06 at 22:40 +0200, Michael Kerrisk (man-pages) wrote:
> >> Hi Davidlohr,
> >>
> >> On Tue, May 6, 2014 at 10:06 PM, Davidlohr Bueso <davidlohr@hp.com> wrote:
> >>> On Fri, 2014-05-02 at 15:16 +0200, Michael Kerrisk (man-pages) wrote:
> >>>> Hi Manfred,
> >>>>
> >>>> On Mon, Apr 21, 2014 at 4:26 PM, Manfred Spraul
> >>>> <manfred@colorfullife.com> wrote:
> >>>>> Hi all,
> >>>>>
> >>>>> the increase of SHMMAX/SHMALL is now a 4 patch series.
> >>>>> I don't have ideas how to improve it further.
> >>>>
> >>>> On the assumption that your patches are heading to mainline, could you
> >>>> send me a man-pages patch for the changes?
> >>>
> >>> Btw, I think that the code could still use some love wrt documentation.
> >>
> >> (Agreed.)
> >>
> >>> Andrew, please consider this for -next if folks agree. Thanks.
> >>>
> >>> 8<----------------------------------------------------------
> >>>
> >>> From: Davidlohr Bueso <davidlohr@hp.com>
> >>> Subject: [PATCH] ipc,shm: document new limits in the uapi header
> >>>
> >>> This is useful in the future and allows users to
> >>> better understand the reasoning behind the changes.
> >>>
> >>> Also use UL as we're dealing with it anyways.
> >>>
> >>> Signed-off-by: Davidlohr Bueso <davidlohr@hp.com>
> >>> ---
> >>>  include/uapi/linux/shm.h | 14 ++++++++------
> >>>  1 file changed, 8 insertions(+), 6 deletions(-)
> >>>
> >>> diff --git a/include/uapi/linux/shm.h b/include/uapi/linux/shm.h
> >>> index 74e786d..e37fb08 100644
> >>> --- a/include/uapi/linux/shm.h
> >>> +++ b/include/uapi/linux/shm.h
> >>> @@ -8,17 +8,19 @@
> >>>  #endif
> >>>
> >>>  /*
> >>> - * SHMMAX, SHMMNI and SHMALL are upper limits are defaults which can
> >>
> >> Something is wrong in the line above (missing word(s)?) ("are upper
> >> limits are defaults")
> >>
> >>> - * be modified by sysctl.
> >>> + * SHMMNI, SHMMAX and SHMALL are the default upper limits which can be
> >>> + * modified by sysctl. Both SHMMAX and SHMALL have their default values
> >>> + * to the maximum limit which is as large as it can be without helping
> >>> + * userspace overflow the values. There is really nothing the kernel
> >>> + * can do to avoid this any variables. It is therefore not advised to
> >>
> >> Something is missing in that last line.
> >>
> >>> + * make them any larger. This is suitable for both 32 and 64-bit systems.
> >>
> >> "This" is not so clear. I suggest replacing with an actual noun.
> > 
> > Good point. Perhaps 'These values are ...' would do instead. 
> 
> That's better.
> 
> Did you miss the first point I raised above?

No, actually our emails crossed paths and I had sent a suggestion before
I replied to yours: https://lkml.org/lkml/2014/5/6/613

Thanks.
Davidlohr