diff options
| author | Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com> | 2015-05-28 15:44:19 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-05-28 18:25:18 -0700 |
| commit | 1f0c27b50f4f2567e649f49d77daee2bbf3f40e5 (patch) | |
| tree | cdf33c9a7a9e676d5be8dc4ac41f5aa8a56760ed /include/trace | |
| parent | e5feb1ebaadfb1f5f70a3591e762d780232a4f5d (diff) | |
tracing/mm: don't trace mm_page_free on offline cpus
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:
.dump_stack+0x98/0xd4 (unreliable)
.lockdep_rcu_suspicious+0x108/0x170
.free_pages_prepare+0x494/0x680
.free_hot_cold_page+0x50/0x280
.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_free 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')
| -rw-r--r-- | include/trace/events/kmem.h | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h index 78efa0a197a9..aa863549e77a 100644 --- a/include/trace/events/kmem.h +++ b/include/trace/events/kmem.h @@ -158,12 +158,24 @@ DEFINE_EVENT_CONDITION(kmem_free, kmem_cache_free, TP_CONDITION(cpu_online(raw_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), + + /* + * 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 ) |