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

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Date:	Wed, 07 May 2014 07:27:25 +0200
From:	"Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
To:	Davidlohr Bueso <davidlohr@...com>
CC:	mtk.manpages@...il.com, Manfred Spraul <manfred@...orfullife.com>,
	Davidlohr Bueso <davidlohr.bueso@...com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Greg Thelen <gthelen@...gle.com>, aswin@...com,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH 0/4] ipc/shm.c: increase the limits for SHMMAX, SHMALL

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@...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@...orfullife.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@...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@...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?

Cheers,

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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