Ccing Paul, On Tue, Apr 28, 2015 at 9:21 PM, Shreyas B. Prabhu <shre...@linux.vnet.ibm.com> wrote: > Since tracepoints use RCU for protection, they must not be called on > offline cpus. trace_mm_page_free can be called on an offline cpu in > this scenario caught by LOCKDEP: > > =============================== > [ INFO: suspicious RCU usage. ] > 4.1.0-rc1+ #9 Not tainted > ------------------------------- > include/trace/events/kmem.h:170 suspicious rcu_dereference_check() usage! > > other info that might help us debug this: > > RCU used illegally from offline CPU! > rcu_scheduler_active = 1, debug_locks = 1 > no locks held by swapper/1/0. > > stack backtrace: > CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.1.0-rc1+ #9 > Call Trace: > [c000001fed2f7790] [c0000000009dee8c] .dump_stack+0x98/0xd4 (unreliable) > [c000001fed2f7810] [c000000000128d88] .lockdep_rcu_suspicious+0x108/0x170 > [c000001fed2f78a0] [c000000000203bc4] .free_pages_prepare+0x494/0x680 > [c000001fed2f7980] [c000000000207fd0] .free_hot_cold_page+0x50/0x280 > [c000001fed2f7a30] [c00000000004d000] .destroy_context+0x90/0xd0 > [c000001fed2f7ab0] [c0000000000bd1d8] .__mmdrop+0x58/0x160 > [c000001fed2f7b40] [c0000000001068e0] .idle_task_exit+0xf0/0x100 > [c000001fed2f7bc0] [c000000000066948] .pnv_smp_cpu_kill_self+0x58/0x2c0 > [c000001fed2f7ca0] [c00000000003ce34] .cpu_die+0x34/0x50 > [c000001fed2f7d10] [c0000000000176d0] .arch_cpu_idle_dead+0x20/0x40 > [c000001fed2f7d80] [c00000000011f9a8] .cpu_startup_entry+0x708/0x7a0 > [c000001fed2f7ec0] [c00000000003cb6c] .start_secondary+0x36c/0x3a0 > [c000001fed2f7f90] [c000000000008b6c] start_secondary_prolog+0x10/0x14 > > Fix this by converting mm_page_free trace point into TRACE_EVENT_CONDITION > where condition is cpu_online(smp_processor_id()) > > Signed-off-by: Shreyas B. Prabhu <shre...@linux.vnet.ibm.com> > --- > include/trace/events/kmem.h | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h > index dd9e612..4abda92 100644 > --- a/include/trace/events/kmem.h > +++ b/include/trace/events/kmem.h > @@ -149,12 +149,14 @@ DEFINE_EVENT_CONDITION(kmem_free, kmem_cache_free, > TP_CONDITION(cpu_online(smp_processor_id())) > ); > > -TRACE_EVENT(mm_page_free, > +TRACE_EVENT_CONDITION(mm_page_free, > > TP_PROTO(struct page *page, unsigned int order), > > TP_ARGS(page, order), > > + TP_CONDITION(cpu_online(smp_processor_id())), > + > TP_STRUCT__entry( > __field( unsigned long, pfn ) > __field( unsigned int, order ) > --
Reviewed-by: Preeti U Murthy <pr...@linux.vnet.ibm.com> Regards Preeti U Murthy > 1.9.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
