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Subject: Re: + prctl-add-pr_set_proctitle_area-option.patch added to -mm
 tree
From: Timo Sirainen <tss@iki.fi>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>, Andrew Morton <akpm@linux-foundation.org>,
       Bryan Donlan <bdonlan@gmail.com>, Ulrich Drepper <drepper@redhat.com>,
       WANG Cong <xiyou.wangcong@gmail.com>, linux-kernel@vger.kernel.org
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On Wed, 2009-11-11 at 02:48 +0900, KOSAKI Motohiro wrote:
> There is unwritten reason. I hope to add /proc/[pid]/cmdline cache. It
> help to avoid
> ps getting stuck by mmap_sem.

Can you explain this further? When would it cache the value and when
would it be returned? I was at least hoping to avoid calling prctl()
every time when I want process title changed.

I think Solaris saves the first 80 chars of the initial cmdline to
kernel memory and gives that to ps. I guess doing something similar and
returning it only when userspace memory can't be accessed would be ok.


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