[PATCH 1/3] tracing/mm: Don't trace kmem_cache_free on offline cpus

[PATCH 1/3] tracing/mm: Don't trace kmem_cache_free on offline cpus

[Shreyas B. Prabhu]

Since tracepoints use RCU for protection, they must not be called on
offline cpus. trace_kmem_cache_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:148 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:
[c000001fed2f78f0] [c0000000009dee8c] .dump_stack+0x98/0xd4 (unreliable)
[c000001fed2f7970] [c000000000128d88] .lockdep_rcu_suspicious+0x108/0x170
[c000001fed2f7a00] [c00000000026f924] .kmem_cache_free+0x344/0x4b0
[c000001fed2f7ab0] [c0000000000bd1cc] .__mmdrop+0x4c/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 kmem_cache_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>
Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 include/trace/events/kmem.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
index 81ea598..dd9e612 100644
--- a/include/trace/events/kmem.h
+++ b/include/trace/events/kmem.h
@@ -140,11 +140,13 @@ DEFINE_EVENT(kmem_free, kfree,
 	TP_ARGS(call_site, ptr)
 );
 
-DEFINE_EVENT(kmem_free, kmem_cache_free,
+DEFINE_EVENT_CONDITION(kmem_free, kmem_cache_free,
 
 	TP_PROTO(unsigned long call_site, const void *ptr),
 
-	TP_ARGS(call_site, ptr)
+	TP_ARGS(call_site, ptr),
+
+	TP_CONDITION(cpu_online(smp_processor_id()))
 );
 
 TRACE_EVENT(mm_page_free,
-- 
1.9.3

[PATCH 2/3] tracing/mm: Don't trace mm_page_free on offline cpus

[Shreyas B. Prabhu]

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 <shreyas@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		)
-- 
1.9.3

Re: [PATCH 2/3] tracing/mm: Don't trace mm_page_free on offline cpus

[Preeti Murthy]

Ccing Paul,

On Tue, Apr 28, 2015 at 9:21 PM, Shreyas B. Prabhu
<shreyas@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 <shreyas@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 <preet@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 majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

Re: [PATCH 2/3] tracing/mm: Don't trace mm_page_free on offline cpus

[Preeti Murthy]

On Wed, Apr 29, 2015 at 2:36 PM, Preeti Murthy <preeti.lkml@gmail.com> wrote:
> Ccing Paul,
>
> On Tue, Apr 28, 2015 at 9:21 PM, Shreyas B. Prabhu
> <shreyas@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 <shreyas@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 <preet@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 majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> Please read the FAQ at  http://www.tux.org/lkml/

[PATCH 3/3] tracing/mm: Don't trace mm_page_pcpu_drain on offline cpus

[Shreyas B. Prabhu]

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:
 [c000001fed2e7720] [c0000000009dee8c] .dump_stack+0x98/0xd4 (unreliable)
 [c000001fed2e77a0] [c000000000128d88] .lockdep_rcu_suspicious+0x108/0x170
 [c000001fed2e7830] [c00000000020794c] .free_pcppages_bulk+0x60c/0x920
 [c000001fed2e7980] [c000000000208188] .free_hot_cold_page+0x208/0x280
 [c000001fed2e7a30] [c00000000004d000] .destroy_context+0x90/0xd0
 [c000001fed2e7ab0] [c0000000000bd1d8] .__mmdrop+0x58/0x160
 [c000001fed2e7b40] [c0000000001068e0] .idle_task_exit+0xf0/0x100
 [c000001fed2e7bc0] [c000000000066948] .pnv_smp_cpu_kill_self+0x58/0x2c0
 [c000001fed2e7ca0] [c00000000003ce34] .cpu_die+0x34/0x50
 [c000001fed2e7d10] [c0000000000176d0] .arch_cpu_idle_dead+0x20/0x40
 [c000001fed2e7d80] [c00000000011f9a8] .cpu_startup_entry+0x708/0x7a0
 [c000001fed2e7ec0] [c00000000003cb6c] .start_secondary+0x36c/0x3a0
 [c000001fed2e7f90] [c000000000008b6c] 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>
---
 include/trace/events/kmem.h | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
index 4abda92..6cd975f 100644
--- a/include/trace/events/kmem.h
+++ b/include/trace/events/kmem.h
@@ -257,12 +257,26 @@ 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),
 
+	TP_CONDITION(cpu_online(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)
-- 
1.9.3

Re: [PATCH 3/3] tracing/mm: Don't trace mm_page_pcpu_drain on offline cpus

[Preeti Murthy]

Ccing Paul,

On Tue, Apr 28, 2015 at 9:21 PM, Shreyas B. Prabhu
<shreyas@linux.vnet.ibm.com> wrote:
> 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:
>  [c000001fed2e7720] [c0000000009dee8c] .dump_stack+0x98/0xd4 (unreliable)
>  [c000001fed2e77a0] [c000000000128d88] .lockdep_rcu_suspicious+0x108/0x170
>  [c000001fed2e7830] [c00000000020794c] .free_pcppages_bulk+0x60c/0x920
>  [c000001fed2e7980] [c000000000208188] .free_hot_cold_page+0x208/0x280
>  [c000001fed2e7a30] [c00000000004d000] .destroy_context+0x90/0xd0
>  [c000001fed2e7ab0] [c0000000000bd1d8] .__mmdrop+0x58/0x160
>  [c000001fed2e7b40] [c0000000001068e0] .idle_task_exit+0xf0/0x100
>  [c000001fed2e7bc0] [c000000000066948] .pnv_smp_cpu_kill_self+0x58/0x2c0
>  [c000001fed2e7ca0] [c00000000003ce34] .cpu_die+0x34/0x50
>  [c000001fed2e7d10] [c0000000000176d0] .arch_cpu_idle_dead+0x20/0x40
>  [c000001fed2e7d80] [c00000000011f9a8] .cpu_startup_entry+0x708/0x7a0
>  [c000001fed2e7ec0] [c00000000003cb6c] .start_secondary+0x36c/0x3a0
>  [c000001fed2e7f90] [c000000000008b6c] 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>
> ---
>  include/trace/events/kmem.h | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
> index 4abda92..6cd975f 100644
> --- a/include/trace/events/kmem.h
> +++ b/include/trace/events/kmem.h
> @@ -257,12 +257,26 @@ 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),
>
> +       TP_CONDITION(cpu_online(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;
> +       ),
> +

What was the need to do the above changes besides adding TP_CONDITION ?

Regards
Preeti U Murthy

Re: [PATCH 3/3] tracing/mm: Don't trace mm_page_pcpu_drain on offline cpus

[Shreyas B Prabhu]

>> -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),
>>
>> +       TP_CONDITION(cpu_online(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;
>> +       ),
>> +
> 
> What was the need to do the above changes besides adding TP_CONDITION ?
> 

IIUC there is no existing macro which can both add a condition and
override printk format, hence the fall back to TRACE_EVENT_CONDITION.

Thanks,
Shreyas

Re: [PATCH 3/3] tracing/mm: Don't trace mm_page_pcpu_drain on offline cpus

[Steven Rostedt]

On Wed, 29 Apr 2015 20:19:28 +0530
Shreyas B Prabhu <shreyas@linux.vnet.ibm.com> wrote:

> IIUC there is no existing macro which can both add a condition and
> override printk format, hence the fall back to TRACE_EVENT_CONDITION.

Hmm, want me to send you a patch that changes that?

-- Steve

Re: [PATCH 3/3] tracing/mm: Don't trace mm_page_pcpu_drain on offline cpus

[Shreyas B Prabhu]

On Wednesday 29 April 2015 08:48 PM, Steven Rostedt wrote:
> On Wed, 29 Apr 2015 20:19:28 +0530
> Shreyas B Prabhu <shreyas@linux.vnet.ibm.com> wrote:
> 
>> IIUC there is no existing macro which can both add a condition and
>> override printk format, hence the fall back to TRACE_EVENT_CONDITION.
> 
> Hmm, want me to send you a patch that changes that?
> 
I am not sure if its worth the effort now. It doesn't look like any
other trace point apart from the above use case will benefit from it.
Only smbus_write and smbus_reply seem to come close. But even they need
separate TP_fast_assign.

Thanks,
Shreyas

Re: [PATCH 3/3] tracing/mm: Don't trace mm_page_pcpu_drain on offline cpus

[Steven Rostedt]

On Wed, 29 Apr 2015 21:28:38 +0530
Shreyas B Prabhu <shreyas@linux.vnet.ibm.com> wrote:

> 
> 
> On Wednesday 29 April 2015 08:48 PM, Steven Rostedt wrote:
> > On Wed, 29 Apr 2015 20:19:28 +0530
> > Shreyas B Prabhu <shreyas@linux.vnet.ibm.com> wrote:
> > 
> >> IIUC there is no existing macro which can both add a condition and
> >> override printk format, hence the fall back to TRACE_EVENT_CONDITION.
> > 
> > Hmm, want me to send you a patch that changes that?
> > 
> I am not sure if its worth the effort now. It doesn't look like any
> other trace point apart from the above use case will benefit from it.
> Only smbus_write and smbus_reply seem to come close. But even they need
> separate TP_fast_assign.

It shouldn't be a problem to implement. But I'm currently cleaning up
those files, and any changes will cause nasty conflicts.

Lets do this. Push the current changes as is, and when I get around to
adding a DEFINE_EVENT_PRINT_CONDITION(), we can modify that code to use
it.

-- Steve

Re: [PATCH 3/3] tracing/mm: Don't trace mm_page_pcpu_drain on offline cpus

[Shreyas B Prabhu]

On Wednesday 29 April 2015 10:38 PM, Steven Rostedt wrote:
>> I am not sure if its worth the effort now. It doesn't look like any
>> other trace point apart from the above use case will benefit from it.
>> Only smbus_write and smbus_reply seem to come close. But even they need
>> separate TP_fast_assign.
> 
> It shouldn't be a problem to implement. But I'm currently cleaning up
> those files, and any changes will cause nasty conflicts.
> 
> Lets do this. Push the current changes as is, and when I get around to
> adding a DEFINE_EVENT_PRINT_CONDITION(), we can modify that code to use
> it.
> 
Okay, sure.

Thanks,
Shreyas

Re: [PATCH 3/3] tracing/mm: Don't trace mm_page_pcpu_drain on offline cpus

[Preeti Murthy]

On Wed, Apr 29, 2015 at 10:49 PM, Shreyas B Prabhu
<shreyas@linux.vnet.ibm.com> wrote:
>
>
> On Wednesday 29 April 2015 10:38 PM, Steven Rostedt wrote:
>>> I am not sure if its worth the effort now. It doesn't look like any
>>> other trace point apart from the above use case will benefit from it.
>>> Only smbus_write and smbus_reply seem to come close. But even they need
>>> separate TP_fast_assign.
>>
>> It shouldn't be a problem to implement. But I'm currently cleaning up
>> those files, and any changes will cause nasty conflicts.
>>
>> Lets do this. Push the current changes as is, and when I get around to
>> adding a DEFINE_EVENT_PRINT_CONDITION(), we can modify that code to use
>> it.
>>
> Okay, sure.

Looks good then.

Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
>
> Thanks,
> Shreyas
>

Re: [PATCH 3/3] tracing/mm: Don't trace mm_page_pcpu_drain on offline cpus

[Shreyas B Prabhu]

On Thursday 30 April 2015 10:06 AM, Preeti Murthy wrote:
> On Wed, Apr 29, 2015 at 10:49 PM, Shreyas B Prabhu
> <shreyas@linux.vnet.ibm.com> wrote:
>>
>>
>> On Wednesday 29 April 2015 10:38 PM, Steven Rostedt wrote:
>>>> I am not sure if its worth the effort now. It doesn't look like any
>>>> other trace point apart from the above use case will benefit from it.
>>>> Only smbus_write and smbus_reply seem to come close. But even they need
>>>> separate TP_fast_assign.
>>>
>>> It shouldn't be a problem to implement. But I'm currently cleaning up
>>> those files, and any changes will cause nasty conflicts.
>>>
>>> Lets do this. Push the current changes as is, and when I get around to
>>> adding a DEFINE_EVENT_PRINT_CONDITION(), we can modify that code to use
>>> it.
>>>
>> Okay, sure.
> 
> Looks good then.
> 
> Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>

Thanks a lot!

Re: [PATCH 3/3] tracing/mm: Don't trace mm_page_pcpu_drain on offline cpus

[Shreyas B Prabhu]

On Wednesday 29 April 2015 10:38 PM, Steven Rostedt wrote:
> On Wed, 29 Apr 2015 21:28:38 +0530
> Shreyas B Prabhu <shreyas@linux.vnet.ibm.com> wrote:
> 
>>
>>
>> On Wednesday 29 April 2015 08:48 PM, Steven Rostedt wrote:
>>> On Wed, 29 Apr 2015 20:19:28 +0530
>>> Shreyas B Prabhu <shreyas@linux.vnet.ibm.com> wrote:
>>>
>>>> IIUC there is no existing macro which can both add a condition and
>>>> override printk format, hence the fall back to TRACE_EVENT_CONDITION.
>>>
>>> Hmm, want me to send you a patch that changes that?
>>>
>> I am not sure if its worth the effort now. It doesn't look like any
>> other trace point apart from the above use case will benefit from it.
>> Only smbus_write and smbus_reply seem to come close. But even they need
>> separate TP_fast_assign.
> 
> It shouldn't be a problem to implement. But I'm currently cleaning up
> those files, and any changes will cause nasty conflicts.
> 
> Lets do this. Push the current changes as is, and when I get around to
> adding a DEFINE_EVENT_PRINT_CONDITION(), we can modify that code to use
> it.
> 

Hi Steve,
Do you have any other suggestions for this patchset or will you take
them as is?

Thanks,
Shreyas

Re: [PATCH 3/3] tracing/mm: Don't trace mm_page_pcpu_drain on offline cpus

[Steven Rostedt]

On Fri, 08 May 2015 10:07:15 +0530
Shreyas B Prabhu <shreyas@linux.vnet.ibm.com> wrote:


> Hi Steve,
> Do you have any other suggestions for this patchset or will you take
> them as is?

I'm fine with them (add my Acked-by), but I don't usually pull in
changes for include/trace/events/*.h files. Those are usually maintained
by the creators of the files (subsystems they represent).

But I could pull them in if need be.

-- Steve

Re: [PATCH 3/3] tracing/mm: Don't trace mm_page_pcpu_drain on offline cpus

[Shreyas B Prabhu]

On Friday 08 May 2015 07:48 PM, Steven Rostedt wrote:
> On Fri, 08 May 2015 10:07:15 +0530
> Shreyas B Prabhu <shreyas@linux.vnet.ibm.com> wrote:
> 
> 
>> Hi Steve,
>> Do you have any other suggestions for this patchset or will you take
>> them as is?
> 
> I'm fine with them (add my Acked-by), but I don't usually pull in
> changes for include/trace/events/*.h files. Those are usually maintained
> by the creators of the files (subsystems they represent).
> 
Oh I didn't know that. Let me resend the patches with your Acked-by,
this time cc'ing people who have added/edited the events.

Thanks,
Shreyas

Re: [PATCH 1/3] tracing/mm: Don't trace kmem_cache_free on offline cpus

[Preeti Murthy]

Ccing Paul,

On Tue, Apr 28, 2015 at 9:21 PM, Shreyas B. Prabhu
<shreyas@linux.vnet.ibm.com> wrote:
> Since tracepoints use RCU for protection, they must not be called on
> offline cpus. trace_kmem_cache_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:148 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:
> [c000001fed2f78f0] [c0000000009dee8c] .dump_stack+0x98/0xd4 (unreliable)
> [c000001fed2f7970] [c000000000128d88] .lockdep_rcu_suspicious+0x108/0x170
> [c000001fed2f7a00] [c00000000026f924] .kmem_cache_free+0x344/0x4b0
> [c000001fed2f7ab0] [c0000000000bd1cc] .__mmdrop+0x4c/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 kmem_cache_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>
> Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> ---
>  include/trace/events/kmem.h | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
> index 81ea598..dd9e612 100644
> --- a/include/trace/events/kmem.h
> +++ b/include/trace/events/kmem.h
> @@ -140,11 +140,13 @@ DEFINE_EVENT(kmem_free, kfree,
>         TP_ARGS(call_site, ptr)
>  );
>
> -DEFINE_EVENT(kmem_free, kmem_cache_free,
> +DEFINE_EVENT_CONDITION(kmem_free, kmem_cache_free,
>
>         TP_PROTO(unsigned long call_site, const void *ptr),
>
> -       TP_ARGS(call_site, ptr)
> +       TP_ARGS(call_site, ptr),
> +
> +       TP_CONDITION(cpu_online(smp_processor_id()))
>  );
>
>  TRACE_EVENT(mm_page_free,

Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>

Regards
Preeti U Murthy
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