From: Aristeu Rozanski <aris@redhat.com>
To: Dave Jones <davej@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: suspicious RCU usage in cgroup
Date: Fri, 5 Oct 2012 18:06:12 -0400 [thread overview]
Message-ID: <20121005220612.GB29956@redhat.com> (raw)
In-Reply-To: <20121005215926.GA2406@redhat.com>
Hi Dave,
On Fri, Oct 05, 2012 at 05:59:29PM -0400, Dave Jones wrote:
> On boot in Linus' current tree..
>
>
> ===============================
> [ INFO: suspicious RCU usage. ]
> 3.6.0+ #22 Not tainted
> -------------------------------
> include/linux/cgroup.h:566 suspicious rcu_dereference_check() usage!
>
> other info that might help us debug this:
>
>
> rcu_scheduler_active = 1, debug_locks = 1
> 2 locks on stack by kdevtmpfs/59:
> #0: blocked: (sb_writers){.+.+.+}, instance: ffff88014595a9a0, at: [<ffffffff81207bc4>] mnt_want_write+0x24/0x50
> #1: held: (&sb->s_type->i_mutex_key#3/1){+.+.+.}, instance: ffff880145b1f5c8, at: [<ffffffff811f26d4>] kern_path_create+0x84/0x170
>
> stack backtrace:
> Pid: 59, comm: kdevtmpfs Not tainted 3.6.0+ #22
> Call Trace:
> [<ffffffff810df1f2>] lockdep_rcu_suspicious+0xe2/0x130
> [<ffffffff81317cad>] devcgroup_inode_mknod+0x19d/0x240
> [<ffffffff812f54d8>] ? security_capable+0x18/0x20
> [<ffffffff8107e214>] ? ns_capable+0x44/0x80
> [<ffffffff811f3b0e>] vfs_mknod+0x7e/0x140
> [<ffffffff81452967>] handle_create.isra.2+0x77/0x210
> [<ffffffff810ddd6c>] ? lock_release_holdtime.part.26+0xcc/0x140
> [<ffffffff810afbf1>] ? get_parent_ip+0x11/0x50
> [<ffffffff816bacd9>] ? sub_preempt_count+0x79/0xd0
> [<ffffffff81452c47>] devtmpfsd+0x147/0x170
> [<ffffffff81452b00>] ? handle_create.isra.2+0x210/0x210
> [<ffffffff8109bf8d>] kthread+0xed/0x100
> [<ffffffff816bacd9>] ? sub_preempt_count+0x79/0xd0
> [<ffffffff816c04a4>] kernel_thread_helper+0x4/0x10
> [<ffffffff810a9fdc>] ? finish_task_switch+0x7c/0x120
> [<ffffffff816b62db>] ? _raw_spin_unlock_irq+0x4b/0x80
> [<ffffffff816b6d37>] ? retint_restore_args+0x13/0x13
> [<ffffffff8109bea0>] ? kthread_create_on_node+0x160/0x160
> [<ffffffff816c04a0>] ? gs_change+0x13/0x13
"[PATCH] cgroup: fix invalid rcu dereference" which is being routed thru
akpm's tree should fix this.
see https://patchwork.kernel.org/patch/1456571/
--
Aristeu
next prev parent reply other threads:[~2012-10-05 22:06 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-05 21:59 suspicious RCU usage in cgroup Dave Jones
2012-10-05 22:06 ` Aristeu Rozanski [this message]
2012-10-17 16:26 ` Dave Jones
2012-10-17 17:40 ` Aristeu Rozanski
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