linux-kernel - Re: [PATCH 1/3] sched, cgroup: reorganize threadgroup locking

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20150514151742.GJ11388@htj.duckdns.org>
Date:	Thu, 14 May 2015 11:17:42 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:	lizefan@...wei.com, cgroups@...r.kernel.org, mingo@...hat.com,
	peterz@...radead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] sched, cgroup: reorganize threadgroup locking

Hello, Sergey.

On Thu, May 14, 2015 at 10:09:13AM +0900, Sergey Senozhatsky wrote:
> > +static inline void threadgroup_change_begin(struct task_struct *tsk)
> >  {
> > -	down_write(&tsk->signal->group_rwsem);
> > +	might_sleep();
> 
> I think cgroup_threadgroup_change_begin()->down_read() already does
> might_sleep() check.

Sure but it's a layering thing.  threadgroup_change_begin() should be
called from a blockable context whether the hook users actually make
use of it or not.  e.g. We want might_sleep() even when
!CONFIG_CGROUP.

Thanks.

-- 
tejun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/