Greetings, An one-shot warning that's rather hard to reproduce.. [ 40.522075] ------------[ cut here ]------------ [ 40.522796] WARNING: at /c/kernel-tests/src/i386/kernel/lockdep.c:956 __bfs+0x1a8/0x1d0() [ 40.523584] Modules linked in: [ 40.523584] Pid: 1, comm: init Not tainted 3.6.0-rc4-00155-gcaa631e #190 [ 40.523584] Call Trace: [ 40.523584] [] warn_slowpath_common+0x64/0x80 [ 40.523584] [] ? __bfs+0x1a8/0x1d0 [ 40.523584] [] ? __bfs+0x1a8/0x1d0 [ 40.523584] [] warn_slowpath_null+0x22/0x30 [ 40.523584] [] __bfs+0x1a8/0x1d0 [ 40.523584] [] ? noop_count+0x10/0x10 [ 40.523584] [] check_usage_backwards+0x63/0xe0 [ 40.523584] [] ? save_stack_trace+0x30/0x50 [ 40.523584] [] ? check_usage_forwards+0xe0/0xe0 [ 40.523584] [] mark_lock+0x139/0x260 [ 40.523584] [] ? check_usage_forwards+0xe0/0xe0 [ 40.523584] [] __lock_acquire+0x530/0x15f0 [ 40.523584] [] ? shrink_dcache_parent+0x60/0x2d0 [ 40.523584] [] ? do_raw_spin_lock+0x16e/0x190 [ 40.523584] [] lock_acquire+0x80/0x190 [ 40.523584] [] ? d_drop+0x1d/0x40 [ 40.523584] [] _raw_spin_lock+0x43/0x50 [ 40.523584] [] ? d_drop+0x1d/0x40 [ 40.523584] [] d_drop+0x1d/0x40 [ 40.523584] [] proc_flush_task+0x8f/0x190 [ 40.523584] [] ? release_task+0x94/0x590 [ 40.523584] [] release_task+0xba/0x590 [ 40.523584] [] ? release_task+0x10/0x590 [ 40.523584] [] ? might_fault+0x91/0xa0 [ 40.523584] [] wait_consider_task.part.24+0xd97/0xed0 [ 40.523584] [] ? wait_consider_task.part.24+0x6c8/0xed0 [ 40.523584] [] do_wait+0xe0/0x300 [ 40.523584] [] ? do_sync_write+0xd0/0xd0 [ 40.523584] [] sys_waitid+0x70/0x170 [ 40.523584] [] ? task_stopped_code+0x50/0x50 [ 40.523584] [] sysenter_do_call+0x12/0x3c Thanks, Fengguang