linux-kernel - [lkp] [ext4] c42b993e20: WARNING: CPU: 4 PID: 716 at lib/kobject.c:690 kobject

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Date:	Thu, 19 May 2016 09:11:25 +0800
From:	kernel test robot <xiaolong.ye@...el.com>
To:	Goldwyn Rodrigues <rgoldwyn@...e.com>
Cc:	0day robot <fengguang.wu@...el.com>,
	LKML <linux-kernel@...r.kernel.org>, lkp@...org,
	ltp@...ts.linux.it
Subject: [lkp] [ext4] c42b993e20: WARNING: CPU: 4 PID: 716 at
 lib/kobject.c:690 kobject_put+0x4b/0x50

FYI, we noticed the following commit:

https://github.com/0day-ci/linux Goldwyn-Rodrigues/kobject-in-sysfs-superblock/20160513-021915
commit c42b993e205c4609db822de74464597564f1b1f7 ("ext4: Let fs create the sysfs entries")

in testcase: ltp
on test machine: nhm-white2: 8 threads Nehalem with 4G memory

caused below changes:


+------------------------------------------+------------+------------+
|                                          | a8f69dff3d | c42b993e20 |
+------------------------------------------+------------+------------+
| boot_successes                           | 4          | 3          |
| boot_failures                            | 0          | 4          |
| WARNING:at_lib/kobject.c:#kobject_put    | 0          | 4          |
| BUG:unable_to_handle_kernel              | 0          | 4          |
| Oops                                     | 0          | 4          |
| RIP:__list_add                           | 0          | 4          |
| Kernel_panic-not_syncing:Fatal_exception | 0          | 4          |
+------------------------------------------+------------+------------+



[   20.135211] EXT4-fs (loop0): mounting ext2 file system using the ext4 subsystem
[   20.135944] EXT4-fs (loop0): mounted filesystem without journal. Opts: (null)
[   20.147798] ------------[ cut here ]------------
[   20.148094] WARNING: CPU: 4 PID: 716 at lib/kobject.c:690 kobject_put+0x4b/0x50
[   20.148582] kobject: '(null)' (ffff88011d548190): is not initialized, yet kobject_put() is being called.
[   20.149104] Modules linked in: loop rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver netconsole sg sr_mod cdrom sd_mod dcdbas coretemp kvm_intel kvm irqbypass crc32c_intel i7core_edac snd_hda_codec_realtek serio_raw pcspkr ata_generic pata_acpi snd_hda_codec_generic edac_core ata_piix libata snd_hda_codec_hdmi usb_storage snd_hda_intel snd_hda_codec firewire_ohci snd_hda_core firewire_core crc_itu_t snd_hwdep snd_pcm snd_timer snd soundcore shpchp acpi_cpufreq broadcom bcm_phy_lib
[   20.152706] CPU: 4 PID: 716 Comm: access06 Not tainted 4.6.0-rc7-00008-gc42b993e #4
[   20.153200] Hardware name: Dell Inc. Studio XPS 8000/0X231R, BIOS A01 08/11/2009
[   20.153637]  0000000000000000 ffff88008b1b3d18 ffffffff8142ea6a ffff88008b1b3d68
[   20.154205]  0000000000000000 ffff88008b1b3d58 ffffffff8107b9c1 000002b281188307
[   20.154774]  ffff88011d548190 ffff88011d548200 ffff88011d548800 0000000000000000
[   20.155343] Call Trace:
[   20.155535]  [<ffffffff8142ea6a>] dump_stack+0x63/0x89
[   20.155827]  [<ffffffff8107b9c1>] __warn+0xd1/0xf0
[   20.156154]  [<ffffffff8107ba2f>] warn_slowpath_fmt+0x4f/0x60
[   20.156469]  [<ffffffff812580e1>] ? mb_cache_destroy+0x101/0x140
[   20.156792]  [<ffffffff814311db>] kobject_put+0x4b/0x50
[   20.157088]  [<ffffffff812a8eeb>] ext4_put_super+0x28b/0x340
[   20.157399]  [<ffffffff811fdf4a>] generic_shutdown_super+0x8a/0x130
[   20.157731]  [<ffffffff811fe077>] kill_block_super+0x27/0x70
[   20.158041]  [<ffffffff811fd963>] deactivate_locked_super+0x43/0x70
[   20.158373]  [<ffffffff811fd9ec>] deactivate_super+0x5c/0x60
[   20.158685]  [<ffffffff8121b06f>] cleanup_mnt+0x3f/0x90
[   20.160796]  [<ffffffff8121b102>] __cleanup_mnt+0x12/0x20
[   20.161097]  [<ffffffff81099516>] task_work_run+0x76/0xb0
[   20.161398]  [<ffffffff81003242>] exit_to_usermode_loop+0xc2/0xd0
[   20.161725]  [<ffffffff81003bd5>] syscall_return_slowpath+0xf5/0x180
[   20.162063]  [<ffffffff818fb53a>] entry_SYSCALL_64_fastpath+0xa2/0xa4
[   20.162463] ---[ end trace ce6b70e95bff5208 ]---
[   20.162741] BUG: unable to handle kernel NULL pointer dereference at           (null)



To reproduce:

        git clone git://git.kernel.org/pub/scm/linux/kernel/git/wfg/lkp-tests.git
        cd lkp-tests
        bin/lkp install job.yaml  # job file is attached in this email
        bin/lkp run     job.yaml



Thanks,
Xiaolong

View attachment "config-4.6.0-rc7-00008-gc42b993e" of type "text/plain" (146993 bytes)

Download attachment "dmesg.xz" of type "application/octet-stream" (17744 bytes)

View attachment "job.yaml" of type "text/plain" (2789 bytes)