linux-kernel - Re: [linux-pm] 2.6.21-rc4-mm1: freezing of processes broken

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 for Android: free password hash cracker in your pocket

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

Message-ID: <20070321171538.GA550@tv-sign.ru>
Date:	Wed, 21 Mar 2007 20:15:38 +0300
From:	Oleg Nesterov <oleg@...sign.ru>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Nigel Cunningham <nigel@...el.suspend2.net>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Sukadev Bhattiprolu <sukadev@...ibm.com>,
	Jiri Slaby <jirislaby@...il.com>, Pavel Machek <pavel@....cz>,
	linux-pm@...ts.osdl.org, linux-kernel@...r.kernel.org
Subject: Re: [linux-pm] 2.6.21-rc4-mm1: freezing of processes broken

On 03/21, Oleg Nesterov wrote:
>
> On 03/21, Andrew Morton wrote:
> >
> > On Wed, 21 Mar 2007 15:45:16 +0100 "Rafael J. Wysocki" <rjw@...k.pl> wrote:
> > 
> > > On Wednesday, 21 March 2007 15:23, Oleg Nesterov wrote:
> > > > > 
> > > > > Could the freezer code be trying to freeze the idle thread as a result?
> > > > 
> > > > Yes. remove-the-likelypid-check-in-copy_process.patch make idle threads
> > > > visible to for_each_process/do_each_thread. Note also that idle threads
> > > > have ->mm != NULL. freezer, oom_kill, move_task_off_dead_cpu, etc, should
> > > > not see idle threads, but they do now.
> > > 
> > > Well, I think this is a good enough reason for asking Andrew to drop this
> > > patch.
> > 
> > Or we change the freezer to skip pid==0 tasks.
> 
> I strongly disagree. In that case we should audit all users of for_each_process.

Just in case, this is not the only problem with this patch. The things like
attach_pid(PIDTYPE_PGID/PIDTYPE_SID) or add_parent() are wrong for the idle
threads unless the parent is "swapper". But this is not always so.

Oleg.

-
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/