On Tue, 2012-07-24 at 17:03 +0800, Fengguang Wu wrote: > Hi Steven, Hi Fengguang,
Just an FYI, It's best to send email to my [email protected] account. I don't check my redhat account every day. > > This looks like some old bug, so I directly report to you w/o trying > to bisect it. It only happens on the attached i386 randconfig and > happens in about half of the kvm boots. > > [ 1.380369] Testing tracer irqsoff: [ 1.524917] > [ 1.525217] =============================== > [ 1.525868] [ INFO: suspicious RCU usage. ] > [ 1.526556] 3.5.0+ #1289 Not tainted > [ 1.527124] ------------------------------- > [ 1.527799] /c/kernel-tests/src/linux/include/linux/rcupdate.h:730 > rcu_read_lock() used illegally while idle! > [ 1.529375] > [ 1.529375] other info that might help us debug this: > [ 1.529375] > [ 1.530667] > [ 1.530667] RCU used illegally from idle CPU! > [ 1.530667] rcu_scheduler_active = 1, debug_locks = 1 > [ 1.532383] RCU used illegally from extended quiescent state! > [ 1.533297] 2 locks held by swapper/0/0: > > [ 1.533924] #0: [ 1.534271] (max_trace_lock){......}, at: > [<410e9d67>] check_critical_timing+0x67/0x1b0 > [ 1.534883] #1: (rcu_read_lock){.+.+..}, at: [<410e1ea0>] > __update_max_tr+0x0/0x200 > > [ 1.534883] stack backtrace: > [ 1.534883] Pid: 0, comm: swapper/0 Not tainted 3.5.0+ #1289 > [ 1.534883] Call Trace: > [ 1.534883] [<41093a76>] lockdep_rcu_suspicious+0xc6/0x100 > [ 1.534883] [<410e2071>] __update_max_tr+0x1d1/0x200 This is very weird because __update_max_tr does not use rcu_read lock(). If you still have the kernel around (or can reproduce it), can you show the objdump of the __update_max_tr function. I wonder if some debug option requires RCU usage somewhere there. Thanks, -- Steve > [ 1.534883] [<410e1ea0>] ? tracing_record_cmdline+0x130/0x130 > [ 1.534883] [<410e30f5>] update_max_tr_single+0x1f5/0x240 > [ 1.534883] [<410e294c>] ? __trace_stack+0x1c/0x30 > [ 1.534883] [<410e9e96>] check_critical_timing+0x196/0x1b0 > [ 1.534883] [<4100b858>] ? default_idle+0x468/0x4c0 > [ 1.534883] [<4100b858>] ? default_idle+0x468/0x4c0 > [ 1.534883] [<410ea47f>] time_hardirqs_on+0xff/0x110 > [ 1.534883] [<410961eb>] ? trace_hardirqs_on+0xb/0x10 > [ 1.534883] [<4100b858>] ? default_idle+0x468/0x4c0 > [ 1.534883] [<41096031>] trace_hardirqs_on_caller+0x11/0x1c0 > [ 1.534883] [<410961eb>] trace_hardirqs_on+0xb/0x10 > [ 1.534883] [<4100b858>] default_idle+0x468/0x4c0 > [ 1.534883] [<4100c4e6>] cpu_idle+0x186/0x190 > [ 1.534883] [<412953c3>] rest_init+0x127/0x134 > [ 1.534883] [<4129529c>] ? __read_lock_failed+0x14/0x14 > [ 1.534883] [<4141b9e0>] start_kernel+0x36f/0x375 > [ 1.534883] [<4141b4a6>] ? repair_env_string+0x51/0x51 > [ 1.534883] [<4141b2d4>] i386_start_kernel+0x8a/0x8f > [ 1.534883] > [ 1.534883] =============================== > > Thanks, > Fengguang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
