Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1755862AbbHCXuV (ORCPT <rfc822;w@1wt.eu>);
	Mon, 3 Aug 2015 19:50:21 -0400
Received: from mail-la0-f46.google.com ([209.85.215.46]:33548 "EHLO
	mail-la0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1754604AbbHCXuT (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Mon, 3 Aug 2015 19:50:19 -0400
MIME-Version: 1.0
Date: Mon, 3 Aug 2015 16:50:18 -0700
Message-ID: <CAHTgTXXxGbjSpT-iyzBrXxGJwdWANUdYionPND2aNO-FYt7taQ@mail.gmail.com>
Subject: Linux 4.1 kernel warning in unregister_blkdev
From: Vinson Lee <vlee@twopensource.com>
To: Jens Axboe <axboe@kernel.dk>
Cc: LKML <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 2065
Lines: 45

Hi.

I've hit this warning multiple times from running the Linux Test
Project ltp_block_dev test case.

ltp_block_dev: Test Case 7: unregister_blkdev() with major=0
------------[ cut here ]------------
WARNING: CPU: 10 PID: 33952 at block/genhd.c:352 unregister_blkdev+0x67/0x9c()
Modules linked in: ltp_block_dev(O) veth tun lp parport coretemp
tcp_diag inet_diag iTCO_wdt iTCO_vendor_support i7core_edac edac_core
i2c_i801 dcdbas kvm ipmi_si ipmi_devintf crc32c_intel ipmi_msghandler
acpi_cpufreq ghash_clmulni_intel ioatdma shpchp lpc_ich mfd_core hed
microcode dell_rbu xfs libcrc32c igb ptp pps_core i2c_algo_bit
i2c_core dca ipv6 [last unloaded: ltp_fw_load]
CPU: 10 PID: 33952 Comm: block_dev Tainted: G           O    4.1.3 #1
 0000000000000009 ffff8811fc8f3cd8 ffffffff81538de8 00000000000000da
 0000000000000000 ffff8811fc8f3d18 ffffffff81068171 ffff8811fc8f3d38
 ffffffff8127f73a 0000000000000000 0000000000000000 ffffffff81f01550
Call Trace:
 [<ffffffff81538de8>] dump_stack+0x45/0x57
 [<ffffffff81068171>] warn_slowpath_common+0xa1/0xbb
 [<ffffffff8127f73a>] ? unregister_blkdev+0x67/0x9c
 [<ffffffff8106822e>] warn_slowpath_null+0x1a/0x1c
 [<ffffffff8127f73a>] unregister_blkdev+0x67/0x9c
 [<ffffffffa00986cf>] sys_tcase+0x59b/0x78f [ltp_block_dev]
 [<ffffffff813744e4>] dev_attr_store+0x18/0x22
 [<ffffffff811d3611>] sysfs_kf_write+0x3e/0x40
 [<ffffffff811d2b2a>] kernfs_fop_write+0xeb/0x13b
 [<ffffffff81172a20>] __vfs_write+0x28/0xa7
 [<ffffffff811759c2>] ? __sb_start_write+0xb0/0xe4
 [<ffffffff8123ea0c>] ? security_file_permission+0x2e/0x33
 [<ffffffff81173245>] vfs_write+0x8f/0xe5
 [<ffffffff81173a57>] SyS_write+0x44/0x78
 [<ffffffff8153e2d7>] system_call_fastpath+0x12/0x6a
---[ end trace ea5af5d6119d362a ]---
ltp_block_dev: Test Case Result: PASS
ltp_block_dev: device released

Cheers,
Vinson
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/