Re: [PATCH v2] powerpc/perf: Fix memory allocation for core-imc based on num_possible_cpus()

2018-05-16 Thread Anju T Sudhakar 



On Wednesday 16 May 2018 12:18 PM, ppaidipe wrote:

On 2018-05-16 12:05, Anju T Sudhakar wrote:

Currently memory is allocated for core-imc based on cpu_present_mask,
which has bit 'cpu' set iff cpu is populated. We use (cpu number / 
threads

per core) as the array index to access the memory.

Under some circumstances firmware marks a CPU as GUARDed CPU and boot 
the

system, until cleared of errors, these CPU's are unavailable for all
subsequent boots. GUARDed CPUs are possible but not present from linux
view, so it blows a hole when we assume the max length of our allocation
is driven by our max present cpus, where as one of the cpus might be 
online

and be beyond the max present cpus, due to the hole.
So (cpu number / threads per core) value bounds the array index and 
leads

to memory overflow.

Call trace observed during a guard test:

Faulting instruction address: 0xc0149f1c
cpu 0x69: Vector: 380 (Data Access Out of Range) at [c03fea303420]
    pc:c0149f1c: prefetch_freepointer+0x14/0x30
    lr:c014e0f8: __kmalloc+0x1a8/0x1ac
    sp:c03fea3036a0
   msr:90009033
   dar:c9c54b2c91dbf6b7
  current = 0xc03fea2c
  paca    = 0xcfddd880 softe: 3 irq_happened: 0x01
    pid   = 1, comm = swapper/104
Linux version 4.16.7-openpower1 (smc@smc-desktop) (gcc version 6.4.0
(Buildroot 2018.02.1-6-ga8d1126)) #2 SMP Fri May 4 16:44:54 PDT 2018
enter ? for help
call trace:
 __kmalloc+0x1a8/0x1ac
 (unreliable)
 init_imc_pmu+0x7f4/0xbf0
 opal_imc_counters_probe+0x3fc/0x43c
 platform_drv_probe+0x48/0x80
 driver_probe_device+0x22c/0x308
 __driver_attach+0xa0/0xd8
 bus_for_each_dev+0x88/0xb4
 driver_attach+0x2c/0x40
 bus_add_driver+0x1e8/0x228
 driver_register+0xd0/0x114
 __platform_driver_register+0x50/0x64
 opal_imc_driver_init+0x24/0x38
 do_one_initcall+0x150/0x15c
 kernel_init_freeable+0x250/0x254
 kernel_init+0x1c/0x150
 ret_from_kernel_thread+0x5c/0xc8

Allocating memory for core-imc based on cpu_possible_mask, which has
bit 'cpu' set iff cpu is populatable, will fix this issue.

Reported-by: Pridhiviraj Paidipeddi 
Signed-off-by: Anju T Sudhakar 
Reviewed-by: Balbir Singh 


I have verified this fix with both normal and kexec boot multiple 
times when
system is having GARDed cores. Not seen any crash/memory corruption 
issues with

this.

Tested-by: Pridhiviraj Paidipeddi 




Thanks.

-Anju


---
 arch/powerpc/perf/imc-pmu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
index d7532e7..75fb23c 100644
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -1146,7 +1146,7 @@ static int init_nest_pmu_ref(void)

 static void cleanup_all_core_imc_memory(void)
 {
-    int i, nr_cores = DIV_ROUND_UP(num_present_cpus(), 
threads_per_core);
+    int i, nr_cores = DIV_ROUND_UP(num_possible_cpus(), 
threads_per_core);

 struct imc_mem_info *ptr = core_imc_pmu->mem_info;
 int size = core_imc_pmu->counter_mem_size;

@@ -1264,7 +1264,7 @@ static int imc_mem_init(struct imc_pmu *pmu_ptr,
struct device_node *parent,
 if (!pmu_ptr->pmu.name)
 return -ENOMEM;

-    nr_cores = DIV_ROUND_UP(num_present_cpus(), threads_per_core);
+    nr_cores = DIV_ROUND_UP(num_possible_cpus(), threads_per_core);
 pmu_ptr->mem_info = kcalloc(nr_cores, sizeof(struct 
imc_mem_info),

 GFP_KERNEL);

Re: [PATCH v2] powerpc/perf: Fix memory allocation for core-imc based on num_possible_cpus()

2018-05-16 Thread ppaidipe 

On 2018-05-16 12:05, Anju T Sudhakar wrote:

Currently memory is allocated for core-imc based on cpu_present_mask,
which has bit 'cpu' set iff cpu is populated. We use (cpu number / 
threads

per core) as the array index to access the memory.

Under some circumstances firmware marks a CPU as GUARDed CPU and boot 
the

system, until cleared of errors, these CPU's are unavailable for all
subsequent boots. GUARDed CPUs are possible but not present from linux
view, so it blows a hole when we assume the max length of our 
allocation
is driven by our max present cpus, where as one of the cpus might be 
online

and be beyond the max present cpus, due to the hole.
So (cpu number / threads per core) value bounds the array index and 
leads

to memory overflow.

Call trace observed during a guard test:

Faulting instruction address: 0xc0149f1c
cpu 0x69: Vector: 380 (Data Access Out of Range) at [c03fea303420]
pc:c0149f1c: prefetch_freepointer+0x14/0x30
lr:c014e0f8: __kmalloc+0x1a8/0x1ac
sp:c03fea3036a0
   msr:90009033
   dar:c9c54b2c91dbf6b7
  current = 0xc03fea2c
  paca= 0xcfddd880   softe: 3irq_happened: 0x01
pid   = 1, comm = swapper/104
Linux version 4.16.7-openpower1 (smc@smc-desktop) (gcc version 6.4.0
(Buildroot 2018.02.1-6-ga8d1126)) #2 SMP Fri May 4 16:44:54 PDT 
2018

enter ? for help
call trace:
 __kmalloc+0x1a8/0x1ac
 (unreliable)
 init_imc_pmu+0x7f4/0xbf0
 opal_imc_counters_probe+0x3fc/0x43c
 platform_drv_probe+0x48/0x80
 driver_probe_device+0x22c/0x308
 __driver_attach+0xa0/0xd8
 bus_for_each_dev+0x88/0xb4
 driver_attach+0x2c/0x40
 bus_add_driver+0x1e8/0x228
 driver_register+0xd0/0x114
 __platform_driver_register+0x50/0x64
 opal_imc_driver_init+0x24/0x38
 do_one_initcall+0x150/0x15c
 kernel_init_freeable+0x250/0x254
 kernel_init+0x1c/0x150
 ret_from_kernel_thread+0x5c/0xc8

Allocating memory for core-imc based on cpu_possible_mask, which has
bit 'cpu' set iff cpu is populatable, will fix this issue.

Reported-by: Pridhiviraj Paidipeddi 
Signed-off-by: Anju T Sudhakar 
Reviewed-by: Balbir Singh 


I have verified this fix with both normal and kexec boot multiple times 
when
system is having GARDed cores. Not seen any crash/memory corruption 
issues with

this.

Tested-by: Pridhiviraj Paidipeddi 



---
 arch/powerpc/perf/imc-pmu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
index d7532e7..75fb23c 100644
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -1146,7 +1146,7 @@ static int init_nest_pmu_ref(void)

 static void cleanup_all_core_imc_memory(void)
 {
-   int i, nr_cores = DIV_ROUND_UP(num_present_cpus(), threads_per_core);
+	int i, nr_cores = DIV_ROUND_UP(num_possible_cpus(), 
threads_per_core);

struct imc_mem_info *ptr = core_imc_pmu->mem_info;
int size = core_imc_pmu->counter_mem_size;

@@ -1264,7 +1264,7 @@ static int imc_mem_init(struct imc_pmu *pmu_ptr,
struct device_node *parent,
if (!pmu_ptr->pmu.name)
return -ENOMEM;

-   nr_cores = DIV_ROUND_UP(num_present_cpus(), threads_per_core);
+   nr_cores = DIV_ROUND_UP(num_possible_cpus(), threads_per_core);
pmu_ptr->mem_info = kcalloc(nr_cores, sizeof(struct 
imc_mem_info),
GFP_KERNEL);

[PATCH v2] powerpc/perf: Fix memory allocation for core-imc based on num_possible_cpus()

2018-05-16 Thread Anju T Sudhakar 
Currently memory is allocated for core-imc based on cpu_present_mask,
which has bit 'cpu' set iff cpu is populated. We use (cpu number / threads
per core) as the array index to access the memory.

Under some circumstances firmware marks a CPU as GUARDed CPU and boot the
system, until cleared of errors, these CPU's are unavailable for all
subsequent boots. GUARDed CPUs are possible but not present from linux
view, so it blows a hole when we assume the max length of our allocation
is driven by our max present cpus, where as one of the cpus might be online
and be beyond the max present cpus, due to the hole. 
So (cpu number / threads per core) value bounds the array index and leads
to memory overflow.

Call trace observed during a guard test:

Faulting instruction address: 0xc0149f1c
cpu 0x69: Vector: 380 (Data Access Out of Range) at [c03fea303420]
pc:c0149f1c: prefetch_freepointer+0x14/0x30
lr:c014e0f8: __kmalloc+0x1a8/0x1ac
sp:c03fea3036a0
   msr:90009033
   dar:c9c54b2c91dbf6b7
  current = 0xc03fea2c
  paca= 0xcfddd880   softe: 3irq_happened: 0x01
pid   = 1, comm = swapper/104
Linux version 4.16.7-openpower1 (smc@smc-desktop) (gcc version 6.4.0
(Buildroot 2018.02.1-6-ga8d1126)) #2 SMP Fri May 4 16:44:54 PDT 2018
enter ? for help
call trace:
 __kmalloc+0x1a8/0x1ac
 (unreliable)
 init_imc_pmu+0x7f4/0xbf0
 opal_imc_counters_probe+0x3fc/0x43c
 platform_drv_probe+0x48/0x80
 driver_probe_device+0x22c/0x308
 __driver_attach+0xa0/0xd8
 bus_for_each_dev+0x88/0xb4
 driver_attach+0x2c/0x40
 bus_add_driver+0x1e8/0x228
 driver_register+0xd0/0x114
 __platform_driver_register+0x50/0x64
 opal_imc_driver_init+0x24/0x38
 do_one_initcall+0x150/0x15c
 kernel_init_freeable+0x250/0x254
 kernel_init+0x1c/0x150
 ret_from_kernel_thread+0x5c/0xc8

Allocating memory for core-imc based on cpu_possible_mask, which has
bit 'cpu' set iff cpu is populatable, will fix this issue.

Reported-by: Pridhiviraj Paidipeddi 
Signed-off-by: Anju T Sudhakar 
Reviewed-by: Balbir Singh 
---
 arch/powerpc/perf/imc-pmu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c
index d7532e7..75fb23c 100644
--- a/arch/powerpc/perf/imc-pmu.c
+++ b/arch/powerpc/perf/imc-pmu.c
@@ -1146,7 +1146,7 @@ static int init_nest_pmu_ref(void)
 
 static void cleanup_all_core_imc_memory(void)
 {
-   int i, nr_cores = DIV_ROUND_UP(num_present_cpus(), threads_per_core);
+   int i, nr_cores = DIV_ROUND_UP(num_possible_cpus(), threads_per_core);
struct imc_mem_info *ptr = core_imc_pmu->mem_info;
int size = core_imc_pmu->counter_mem_size;
 
@@ -1264,7 +1264,7 @@ static int imc_mem_init(struct imc_pmu *pmu_ptr, struct 
device_node *parent,
if (!pmu_ptr->pmu.name)
return -ENOMEM;
 
-   nr_cores = DIV_ROUND_UP(num_present_cpus(), threads_per_core);
+   nr_cores = DIV_ROUND_UP(num_possible_cpus(), threads_per_core);
pmu_ptr->mem_info = kcalloc(nr_cores, sizeof(struct 
imc_mem_info),
GFP_KERNEL);
 
-- 
2.7.4