[PATCH 2/2] x86/tlb/trace: Do not trace on CPU that is offline
From: "Steven Rostedt (Red Hat)"
When taking a CPU down for suspend and resume, a tracepoint may be called
when the CPU has been designated offline. As tracepoints require RCU for
protection, they must not be called if the current CPU is offline.
Unfortunately, trace_tlb_flush() is called in this scenario as was noted
by LOCKDEP:
...
Disabling non-boot CPUs ...
intel_pstate CPU 1 exiting
===
smpboot: CPU 1 didn't die...
[ INFO: suspicious RCU usage. ]
3.19.0-rc7-next-20150204.1-iniza-small #1 Not tainted
---
include/trace/events/tlb.h:35 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 = 0
no locks held by swapper/1/0.
stack backtrace:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted
3.19.0-rc7-next-20150204.1-iniza-small #1
Hardware name: SAMSUNG ELECTRONICS CO., LTD.
530U3BI/530U4BI/530U4BH/530U3BI/530U4BI/530U4BH, BIOS 13XK 03/28/2013
0001 88011a44fe18 817e370d 0011
88011a448290 88011a44fe48 810d6847 8800c66b9600
0001 88011a44c000 81cb3900 88011a44fe78
Call Trace:
[] dump_stack+0x4c/0x65
[] lockdep_rcu_suspicious+0xe7/0x120
[] idle_task_exit+0x205/0x2c0
[] play_dead_common+0xe/0x50
[] native_play_dead+0x15/0x140
[] arch_cpu_idle_dead+0xf/0x20
[] cpu_startup_entry+0x37e/0x580
[] start_secondary+0x140/0x150
intel_pstate CPU 2 exiting
...
By converting the tlb_flush tracepoint to a TRACE_EVENT_CONDITION where the
condition is cpu_online(smp_processor_id()), we can avoid calling RCU protected
code when the CPU is offline.
Link:
http://lkml.kernel.org/r/CA+icZUUGiGDoL5NU8RuxKzFjoLjEKRtUWx=jb8b9a0eqv-e...@mail.gmail.com
Cc: sta...@vger.kernel.org # 3.17+
Fixes: d17d8f9dedb9 "x86/mm: Add tracepoints for TLB flushes"
Reported-by: Sedat Dilek
Tested-by: Sedat Dilek
Suggested-by: Paul E. McKenney
Acked-by: Paul E. McKenney
Acked-by: Dave Hansen
Signed-off-by: Steven Rostedt
---
include/trace/events/tlb.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/include/trace/events/tlb.h b/include/trace/events/tlb.h
index 13391d288107..0e7635765153 100644
--- a/include/trace/events/tlb.h
+++ b/include/trace/events/tlb.h
@@ -13,11 +13,13 @@
{ TLB_LOCAL_SHOOTDOWN, "local shootdown" },\
{ TLB_LOCAL_MM_SHOOTDOWN, "local mm shootdown" }
-TRACE_EVENT(tlb_flush,
+TRACE_EVENT_CONDITION(tlb_flush,
TP_PROTO(int reason, unsigned long pages),
TP_ARGS(reason, pages),
+ TP_CONDITION(cpu_online(smp_processor_id())),
+
TP_STRUCT__entry(
__field( int, reason)
__field(unsigned long, pages)
--
2.1.4
--
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[PATCH 2/2] x86/tlb/trace: Do not trace on CPU that is offline
From: Steven Rostedt (Red Hat) rost...@goodmis.org
When taking a CPU down for suspend and resume, a tracepoint may be called
when the CPU has been designated offline. As tracepoints require RCU for
protection, they must not be called if the current CPU is offline.
Unfortunately, trace_tlb_flush() is called in this scenario as was noted
by LOCKDEP:
...
Disabling non-boot CPUs ...
intel_pstate CPU 1 exiting
===
smpboot: CPU 1 didn't die...
[ INFO: suspicious RCU usage. ]
3.19.0-rc7-next-20150204.1-iniza-small #1 Not tainted
---
include/trace/events/tlb.h:35 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 = 0
no locks held by swapper/1/0.
stack backtrace:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted
3.19.0-rc7-next-20150204.1-iniza-small #1
Hardware name: SAMSUNG ELECTRONICS CO., LTD.
530U3BI/530U4BI/530U4BH/530U3BI/530U4BI/530U4BH, BIOS 13XK 03/28/2013
0001 88011a44fe18 817e370d 0011
88011a448290 88011a44fe48 810d6847 8800c66b9600
0001 88011a44c000 81cb3900 88011a44fe78
Call Trace:
[817e370d] dump_stack+0x4c/0x65
[810d6847] lockdep_rcu_suspicious+0xe7/0x120
[810b71a5] idle_task_exit+0x205/0x2c0
[81054c4e] play_dead_common+0xe/0x50
[81054ca5] native_play_dead+0x15/0x140
[8102963f] arch_cpu_idle_dead+0xf/0x20
[810cd89e] cpu_startup_entry+0x37e/0x580
[81053e20] start_secondary+0x140/0x150
intel_pstate CPU 2 exiting
...
By converting the tlb_flush tracepoint to a TRACE_EVENT_CONDITION where the
condition is cpu_online(smp_processor_id()), we can avoid calling RCU protected
code when the CPU is offline.
Link:
http://lkml.kernel.org/r/CA+icZUUGiGDoL5NU8RuxKzFjoLjEKRtUWx=jb8b9a0eqv-e...@mail.gmail.com
Cc: sta...@vger.kernel.org # 3.17+
Fixes: d17d8f9dedb9 x86/mm: Add tracepoints for TLB flushes
Reported-by: Sedat Dilek sedat.di...@gmail.com
Tested-by: Sedat Dilek sedat.di...@gmail.com
Suggested-by: Paul E. McKenney paul...@linux.vnet.ibm.com
Acked-by: Paul E. McKenney paul...@linux.vnet.ibm.com
Acked-by: Dave Hansen d...@sr71.net
Signed-off-by: Steven Rostedt rost...@goodmis.org
---
include/trace/events/tlb.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/include/trace/events/tlb.h b/include/trace/events/tlb.h
index 13391d288107..0e7635765153 100644
--- a/include/trace/events/tlb.h
+++ b/include/trace/events/tlb.h
@@ -13,11 +13,13 @@
{ TLB_LOCAL_SHOOTDOWN, local shootdown },\
{ TLB_LOCAL_MM_SHOOTDOWN, local mm shootdown }
-TRACE_EVENT(tlb_flush,
+TRACE_EVENT_CONDITION(tlb_flush,
TP_PROTO(int reason, unsigned long pages),
TP_ARGS(reason, pages),
+ TP_CONDITION(cpu_online(smp_processor_id())),
+
TP_STRUCT__entry(
__field( int, reason)
__field(unsigned long, pages)
--
2.1.4
--
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/
