From: David Howells <dhowells@redhat.com>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: dhowells@redhat.com,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: oom: __task_cred() need rcu_read_lock()
Date: Thu, 19 Aug 2010 16:06:34 +0100 [thread overview]
Message-ID: <7682.1282230394@redhat.com> (raw)
In-Reply-To: <20100819220338.5FD5.A69D9226@jp.fujitsu.com>
KOSAKI Motohiro <kosaki.motohiro@jp.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.
David
WARNING: multiple messages have this Message-ID (diff)
From: David Howells <dhowells@redhat.com>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: dhowells@redhat.com,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: oom: __task_cred() need rcu_read_lock()
Date: Thu, 19 Aug 2010 16:06:34 +0100 [thread overview]
Message-ID: <7682.1282230394@redhat.com> (raw)
In-Reply-To: <20100819220338.5FD5.A69D9226@jp.fujitsu.com>
KOSAKI Motohiro <kosaki.motohiro@jp.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.
David
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next prev parent reply other threads:[~2010-08-19 15:07 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-19 13:06 oom: __task_cred() need rcu_read_lock() KOSAKI Motohiro
2010-08-19 13:06 ` KOSAKI Motohiro
2010-08-19 15:06 ` David Howells [this message]
2010-08-19 15:06 ` David Howells
2010-08-20 0:08 ` KOSAKI Motohiro
2010-08-20 0:08 ` KOSAKI Motohiro
2010-08-20 8:50 ` David Howells
2010-08-20 8:50 ` David Howells
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