linux-kernel - Re: rcu: eqs related warnings in linux-next

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: <20120928133633.GC12843@somewhere.redhat.com>
Date:	Fri, 28 Sep 2012 15:36:43 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Sasha Levin <levinsasha928@...il.com>
Cc:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Dave Jones <davej@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: rcu: eqs related warnings in linux-next

On Fri, Sep 28, 2012 at 02:51:03PM +0200, Sasha Levin wrote:
> Hi all,
> 
> While fuzzing with trinity inside a KVM tools guest with the latest linux-next kernel, I've stumbled on the following during boot:
> 
> [  199.224369] WARNING: at kernel/rcutree.c:513 rcu_eqs_exit_common+0x4a/0x3a0()
> [  199.225307] Pid: 1, comm: init Tainted: G        W    3.6.0-rc7-next-20120928-sasha-00001-g8b2d05d-dirty #13
> [  199.226611] Call Trace:
> [  199.226951]  [<ffffffff811c8d1a>] ? rcu_eqs_exit_common+0x4a/0x3a0
> [  199.227773]  [<ffffffff81108e36>] warn_slowpath_common+0x86/0xb0
> [  199.228572]  [<ffffffff81108f25>] warn_slowpath_null+0x15/0x20
> [  199.229348]  [<ffffffff811c8d1a>] rcu_eqs_exit_common+0x4a/0x3a0
> [  199.230037]  [<ffffffff8117f267>] ? __lock_acquire+0x1c37/0x1ca0
> [  199.230037]  [<ffffffff811c936c>] rcu_eqs_exit+0x9c/0xb0
> [  199.230037]  [<ffffffff811c940c>] rcu_user_exit+0x8c/0xf0
> [  199.230037]  [<ffffffff810a98bb>] do_page_fault+0x1b/0x40
> [  199.230037]  [<ffffffff810a2a90>] do_async_page_fault+0x30/0xa0
> [  199.230037]  [<ffffffff83a3eea8>] async_page_fault+0x28/0x30
> [  199.230037]  [<ffffffff819f357b>] ? debug_object_activate+0x6b/0x1b0
> [  199.230037]  [<ffffffff819f3586>] ? debug_object_activate+0x76/0x1b0
> [  199.230037]  [<ffffffff8111af13>] ? lock_timer_base.isra.19+0x33/0x70
> [  199.230037]  [<ffffffff8111d45f>] mod_timer_pinned+0x9f/0x260
> [  199.230037]  [<ffffffff811c5ff4>] rcu_eqs_enter_common+0x894/0x970
> [  199.230037]  [<ffffffff839dc2ac>] ? init_post+0x75/0xc8
> [  199.230037]  [<ffffffff85abfed5>] ? kernel_init+0x1e1/0x1e1
> [  199.230037]  [<ffffffff811c63df>] rcu_eqs_enter+0xaf/0xc0
> [  199.230037]  [<ffffffff811c64c5>] rcu_user_enter+0xd5/0x140
> [  199.230037]  [<ffffffff8107d0fd>] syscall_trace_leave+0xfd/0x150
> [  199.230037]  [<ffffffff83a3f7af>] int_check_syscall_exit_work+0x34/0x3d
> [  199.230037] ---[ end trace a582c3a264d5bd1a ]---

Ok, we can't decently protect against any kind of exception messing up everything
in the middle of RCU APIs anyway. The only solution is to find out what cause this
page fault in mod_timer_pinned() and work around that.

Anybody, an idea?
--
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/