linux-kernel - Re: [RFC 14/18] limits: track RLIMIT

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Message-ID: <a1ad08ff-0dd6-a580-832b-92e8b49435c2@gmail.com>
Date:	Tue, 14 Jun 2016 15:51:32 +0000
From:	Topi Miettinen <toiwoton@...il.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>,
	Amanieu d'Antras <amanieu@...il.com>,
	Stas Sergeev <stsp@...t.ru>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Wang Xiaoqiang <wangxq10@....edu.cn>,
	Helge Deller <deller@....de>,
	Sasha Levin <sasha.levin@...cle.com>
Subject: Re: [RFC 14/18] limits: track RLIMIT_SIGPENDING actual max

On 06/14/16 14:50, Oleg Nesterov wrote:
> On 06/13, Topi Miettinen wrote:
>>
>> Track maximum number of pending signals, presented in /proc/self/limits.
>>
>> Signed-off-by: Topi Miettinen <toiwoton@...il.com>
>> ---
>>  kernel/signal.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/kernel/signal.c b/kernel/signal.c
>> index 96e9bc4..c8fbccd 100644
>> --- a/kernel/signal.c
>> +++ b/kernel/signal.c
>> @@ -387,6 +387,8 @@ __sigqueue_alloc(int sig, struct task_struct *t, gfp_t flags, int override_rlimi
>>  		INIT_LIST_HEAD(&q->list);
>>  		q->flags = 0;
>>  		q->user = user;
>> +		/* XXX resource limits apply per task, not per user */
>> +		bump_rlimit(RLIMIT_SIGPENDING, atomic_read(&user->sigpending));
> 
> Well, I have to admit that I too dislike the very idea of these changes...
> 
> But this particular patch looks wrong in any case. I wasn't cc'ed on the
> previous patches which add bump_rlimit(), but I have found
> 
> 	"[RFC 05/18] limits: track and present RLIMIT_NOFILE actual max"
> 	http://marc.info/?l=linux-fsdevel&m=146584742331072&w=2
> 

I used git send-email --cc-cmd=scripts/get_maintainer.pl to generate the
CC lists. Is there a better way?

> and bump_rlimit() changes current->signal->rlim_curmax, while in this case
> you need to bump t->signal->rlim_curmax.
> 
> Oleg.
> 

Yes, I also added task_bump_rlimit() which would be better choice here.

-Topi