Messages in this thread | | | Subject | Re: [bug] lockdep warning: module_mutex vs. ftrace_lock | From | Steven Rostedt <> | Date | Mon, 13 Apr 2009 10:08:27 -0400 |
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Sorry for the late reply, I just got back from San Fran, and I do not check my Red Hat email while I'm traveling.
On Tue, 2009-04-07 at 20:30 +0200, Frederic Weisbecker wrote: > On Tue, Apr 07, 2009 at 06:34:56PM +0200, Miklos Szeredi wrote: > > ======================================================= > > [ INFO: possible circular locking dependency detected ] > > 2.6.29-09854-gd508afb-dirty #6 > > ------------------------------------------------------- > > modprobe/3184 is trying to acquire lock: > > (ftrace_lock){+.+.+.}, at: [<ffffffff80277e71>] ftrace_convert_nops+0x32/0x267 > > > > but task is already holding lock: > > (module_mutex){+.+.+.}, at: [<ffffffff8026a539>] sys_init_module+0x3f/0x1d3 > > > > which lock already depends on the new lock. > > > > > > the existing dependency chain (in reverse order) is: > > > > -> #1 (module_mutex){+.+.+.}: > > [<ffffffff8026134a>] __lock_acquire+0x12fe/0x1668 > > [<ffffffff802617a2>] lock_acquire+0xee/0x112 > > [<ffffffff804fe0a6>] mutex_lock_nested+0x4f/0x305 > > [<ffffffff8026709e>] module_update_tracepoints+0x1c/0x73 > > [<ffffffff80274f74>] tracepoint_update_probes+0x21/0x23 > > [<ffffffff8027510a>] tracepoint_probe_register+0x4a/0x68 > > [<ffffffff80277cae>] register_ftrace_graph+0x2a9/0x30f > > [<ffffffff8027f928>] trace_selftest_startup_function_graph+0x2e/0xbb > > [<ffffffff8027fdc5>] register_tracer+0x151/0x26e > > [<ffffffff8070b942>] init_graph_trace+0x10/0x12 > > [<ffffffff80209066>] do_one_initcall+0x5b/0x135 > > [<ffffffff806fa5e4>] kernel_init+0x12f/0x185 > > [<ffffffff8020c2ba>] child_rip+0xa/0x20 > > [<ffffffffffffffff>] 0xffffffffffffffff > > > > -> #0 (ftrace_lock){+.+.+.}: > > [<ffffffff80261067>] __lock_acquire+0x101b/0x1668 > > [<ffffffff802617a2>] lock_acquire+0xee/0x112 > > [<ffffffff804fe0a6>] mutex_lock_nested+0x4f/0x305 > > [<ffffffff80277e71>] ftrace_convert_nops+0x32/0x267 > > [<ffffffff802780bd>] ftrace_init_module+0x17/0x19 > > [<ffffffff8026a011>] load_module+0x1122/0x160b > > [<ffffffff8026a556>] sys_init_module+0x5c/0x1d3 > > [<ffffffff8020b21b>] system_call_fastpath+0x16/0x1b > > [<ffffffffffffffff>] 0xffffffffffffffff > > > > Ah that's this ftrace/modules lock dependency that Steven told me about > recently. Steven, do you know more about it now?
Yeah, I think I submitted a patch to fix that. I'll check my repo.
-- Steve
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