On Sun, Aug 23, 2009 at 12:33:56PM -0700, Paul E. McKenney wrote: > On Sun, Aug 23, 2009 at 08:42:02PM +0200, Ingo Molnar wrote: > > > > * tip-bot for Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> wrote: > > > > > Commit-ID: bc33f24bdca8b6e97376e3a182ab69e6cdefa989 > > > Gitweb: http://git.kernel.org/tip/bc33f24bdca8b6e97376e3a182ab69e6cdefa989 > > > Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> > > > AuthorDate: Sat, 22 Aug 2009 13:56:47 -0700 > > > Committer: Ingo Molnar <mingo@xxxxxxx> > > > CommitDate: Sun, 23 Aug 2009 10:32:37 +0200 > > > > > > rcu: Consolidate sparse and lockdep declarations in include/linux/rcupdate.h > > > > -tip testing found a spontaneous reboot crash, which i > > bisected back to this commit: > > > > bc33f24bdca8b6e97376e3a182ab69e6cdefa989 is first bad commit > > > > the reboot happens during the ftrace syscall tracepoints > > self-test: > > > > [ 34.618832] Testing event sys_exit_set_robust_list: OK > > [ 34.635511] Testing event sys_enter_get_robust_list: OK > > [ 34.652164] Testing event sys_exit_get_robust_list: OK > > [ 34.668844] Testing event sys_enter_futex: OK > > [ 34.685495] Testing event sys_exit_futex: OK > > [ 34.702170] Testing event lock_acquire: [instant reboot] > > > > There's no log message - just a reboot - which signals some > > severe crash - perhaps some locking related infinite > > recursion or something like that? > > Pretty impressive for having mostly moved RCU's lockdep-related > declarations from one file to another... :-/ > > Looking into it, probably a typo on my part. I rechecked this several times, and don't see how anything else should have noticed this patch. That said, that self-test is rather amazing code, so... For the moment, I will simply drop bc33f24bdca8 from my stack. For one thing, once CONFIG_PREEMPT_RCU is dropped, there is much less advantage to consolidating these annotations. But I do have one stupid question... Given that rcu_read_lock() cannot participate in deadlock cycles, why is lockdep tracking it? In any case, I will send a new stack in a day or so (currently testing) that drops bc33f24bdca8 and adds some changes that make CPU hotplug work much better for CONFIG_TREE_PREEMPT_RCU. Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|