linux-kernel - Re: oom: __task_cred() need rcu_read

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: <20100820084820.5FDB.A69D9226@jp.fujitsu.com>
Date:	Fri, 20 Aug 2010 09:08:52 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	David Howells <dhowells@...hat.com>
Cc:	kosaki.motohiro@...fujitsu.com,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Rientjes <rientjes@...gle.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: oom: __task_cred() need rcu_read_lock()

Hi

> KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> wrote:
> 
> > dump_tasks() can call __task_cred() safely because we are holding
> > tasklist_lock. but rcu lock validator don't have enough knowledge and
> > it makes following annoying warning.
> 
> No, it can't.  The tasklist_lock is not protection against the creds changing
> on another CPU.

Thank you for correction.

I suppose you mean I missed CONFIG_TREE_PREEMPT_RCU, right?
As far as my grepping, other rcu implementation and spinlock use 
preempt_disable(). In other word, Can I assume usual distro user 
don't hit this issue?

Thanks.



--
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/