aboutsummaryrefslogtreecommitdiff
path: root/include/trace/events/kmem.h
diff options
context:
space:
mode:
authorShreyas B. Prabhu <shreyas@linux.vnet.ibm.com>2015-05-28 15:44:22 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-05-28 18:25:18 -0700
commit649b8de2f75145bf14cb1783688e16d51ac9b89a (patch)
tree6f6429fc37f6343c71f55b5df4d76e2c0f4e78f5 /include/trace/events/kmem.h
parent1f0c27b50f4f2567e649f49d77daee2bbf3f40e5 (diff)
download96b-common-649b8de2f75145bf14cb1783688e16d51ac9b89a.tar.gz
tracing/mm: don't trace mm_page_pcpu_drain on offline cpus
Since tracepoints use RCU for protection, they must not be called on offline cpus. trace_mm_page_pcpu_drain 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:265 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 1 lock held by swapper/5/0: #0: (&(&zone->lock)->rlock){..-...}, at: [<c0000000002073b0>] .free_pcppages_bulk+0x70/0x920 stack backtrace: CPU: 5 PID: 0 Comm: swapper/5 Not tainted 4.1.0-rc1+ #9 Call Trace: .dump_stack+0x98/0xd4 (unreliable) .lockdep_rcu_suspicious+0x108/0x170 .free_pcppages_bulk+0x60c/0x920 .free_hot_cold_page+0x208/0x280 .destroy_context+0x90/0xd0 .__mmdrop+0x58/0x160 .idle_task_exit+0xf0/0x100 .pnv_smp_cpu_kill_self+0x58/0x2c0 .cpu_die+0x34/0x50 .arch_cpu_idle_dead+0x20/0x40 .cpu_startup_entry+0x708/0x7a0 .start_secondary+0x36c/0x3a0 start_secondary_prolog+0x10/0x14 Fix this by converting mm_page_pcpu_drain trace point into TRACE_EVENT_CONDITION where condition is cpu_online(smp_processor_id()) Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com> Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/trace/events/kmem.h')
-rw-r--r--include/trace/events/kmem.h25
1 files changed, 24 insertions, 1 deletions
diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
index aa863549e77a..f7554fd7fc62 100644
--- a/include/trace/events/kmem.h
+++ b/include/trace/events/kmem.h
@@ -276,12 +276,35 @@ DEFINE_EVENT(mm_page, mm_page_alloc_zone_locked,
TP_ARGS(page, order, migratetype)
);
-DEFINE_EVENT_PRINT(mm_page, mm_page_pcpu_drain,
+TRACE_EVENT_CONDITION(mm_page_pcpu_drain,
TP_PROTO(struct page *page, unsigned int order, int migratetype),
TP_ARGS(page, order, migratetype),
+ /*
+ * This trace can be potentially called from an offlined cpu.
+ * Since trace points use RCU and RCU should not be used from
+ * offline cpus, filter such calls out.
+ * While this trace can be called from a preemptable section,
+ * it has no impact on the condition since tasks can migrate
+ * only from online cpus to other online cpus. Thus its safe
+ * to use raw_smp_processor_id.
+ */
+ TP_CONDITION(cpu_online(raw_smp_processor_id())),
+
+ TP_STRUCT__entry(
+ __field( unsigned long, pfn )
+ __field( unsigned int, order )
+ __field( int, migratetype )
+ ),
+
+ TP_fast_assign(
+ __entry->pfn = page ? page_to_pfn(page) : -1UL;
+ __entry->order = order;
+ __entry->migratetype = migratetype;
+ ),
+
TP_printk("page=%p pfn=%lu order=%d migratetype=%d",
pfn_to_page(__entry->pfn), __entry->pfn,
__entry->order, __entry->migratetype)