kernfs: WARNING: CPU: 59 PID: 10414 at lib/debugobjects.c:260

From: Sasha Levin
Date: Sun Dec 22 2013 - 15:46:54 EST


Hi all,

While fuzzing with trinity inside a KVM tools guest running latest -next kernel, I've stumbled on the following spew.

Beyond regular trinity fuzzing, the machine was in the middle of attempting to offline all of it's cpus (64 of them).

[ 645.148744] WARNING: CPU: 59 PID: 10414 at lib/debugobjects.c:260 debug_print_object
+0x8d/0xb0()
[ 645.150844] ODEBUG: free active (active state 0) object type: timer_list hint: delay
ed_work_timer_fn+0x0/0x20
[ 645.152178] Modules linked in:
[ 645.152699] CPU: 59 PID: 10414 Comm: sh Tainted: G W 3.13.0-rc4-next-20131
220-sasha-00013-gf9a57f1-dirty #6
[ 645.154113] 0000000000000104 ffff88001a74fa68 ffffffff845d3d3c ffffffff858006ee
[ 645.155294] ffff88001a74fab8 ffff88001a74faa8 ffffffff8112f93c ffff88001a74fad8
[ 645.155294] ffffffff8594fab2 ffff880168f10a10 ffffffff86068c00 ffffffff8891eaf8
[ 645.157180] Call Trace:
[ 645.157697] [<ffffffff845d3d3c>] dump_stack+0x52/0x7f
[ 645.157975] [<ffffffff8112f93c>] warn_slowpath_common+0x8c/0xc0
[ 645.158744] [<ffffffff8112fa26>] warn_slowpath_fmt+0x46/0x50
[ 645.158744] [<ffffffff81adcd2d>] debug_print_object+0x8d/0xb0
[ 645.158744] [<ffffffff81153130>] ? __queue_work+0x3f0/0x3f0
[ 645.158744] [<ffffffff81add535>] __debug_check_no_obj_freed+0xa5/0x220
[ 645.158744] [<ffffffff8107e346>] ? cpuid4_cache_sysfs_exit+0x46/0xc0
[ 645.158744] [<ffffffff8107e346>] ? cpuid4_cache_sysfs_exit+0x46/0xc0
[ 645.158744] [<ffffffff81add6c5>] debug_check_no_obj_freed+0x15/0x20
[ 645.158744] [<ffffffff812ae4bf>] kfree+0x21f/0x2e0
[ 645.158744] [<ffffffff8107e346>] cpuid4_cache_sysfs_exit+0x46/0xc0
[ 645.158744] [<ffffffff8107ebea>] cache_remove_dev+0x11a/0x130
[ 645.158744] [<ffffffff8107f128>] cacheinfo_cpu_callback+0x78/0x90
[ 645.158744] [<ffffffff845e027e>] notifier_call_chain+0xee/0x130
[ 645.158744] [<ffffffff8116273e>] __raw_notifier_call_chain+0xe/0x10
[ 645.158744] [<ffffffff8112fbe0>] __cpu_notify+0x20/0x40
[ 645.158744] [<ffffffff8112fc15>] cpu_notify_nofail+0x15/0x30
[ 645.158744] [<ffffffff845caf75>] _cpu_down+0x195/0x2e0
[ 645.158744] [<ffffffff8112fc97>] ? cpu_maps_update_begin+0x17/0x20
[ 645.158744] [<ffffffff8207f745>] ? device_offline+0x55/0xd0
[ 645.158744] [<ffffffff845c9825>] ? klist_next+0xf5/0x120
[ 645.158744] [<ffffffff845d67cd>] ? mutex_trylock+0x1fd/0x270
[ 645.158744] [<ffffffff845cb0f6>] cpu_down+0x36/0x50
[ 645.158744] [<ffffffff82086034>] cpu_subsys_offline+0x14/0x20
[ 645.158744] [<ffffffff8207f772>] device_offline+0x82/0xd0
[ 645.158744] [<ffffffff820806d8>] online_store+0x58/0x80
[ 645.158744] [<ffffffff8207e6d0>] dev_attr_store+0x20/0x30
[ 645.158744] [<ffffffff8135d62f>] sysfs_kf_write+0x4f/0x70
[ 645.158744] [<ffffffff8136160b>] kernfs_fop_write+0xdb/0x140
[ 645.158744] [<ffffffff812d51a3>] vfs_write+0xf3/0x1e0
[ 645.158744] [<ffffffff812d5392>] SyS_write+0x62/0xa0
[ 645.158744] [<ffffffff845e4e90>] tracesys+0xdd/0xe2


Thanks,
Sasha
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