Re: [PATCH] mm/memcontrol.c: add memory allocation result check

[Michal Hocko]

On Mon 30-05-16 17:28:40, Wenwei Tao wrote:
> I think explicit BUG_ON may make the debug easier, since it can point
> out the wrong line.

Does it? NULL ptr dereferencec 6 lines below sounds pretty close to me.
I am not nacking this patch I just think it doesn't add much. If others
think it will be useful I will not object.

> 2016-05-30 16:53 GMT+08:00 Michal Hocko :
> > On Mon 30-05-16 16:45:51, Wenwei Tao wrote:
> >> From: Wenwei Tao 
> >>
> >> The mem_cgroup_tree_per_node allocation might fail,
> >> check that before continue the memcg init. Since it
> >> is in the init phase, trigger the panic if that failure
> >> happens.
> >
> > We would blow up in the very same function so what is the point of the
> > explicit BUG_ON?
> >
> >> Signed-off-by: Wenwei Tao 
> >> ---
> >>  mm/memcontrol.c | 1 +
> >>  1 file changed, 1 insertion(+)
> >>
> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> >> index 925b431..6385c62 100644
> >> --- a/mm/memcontrol.c
> >> +++ b/mm/memcontrol.c
> >> @@ -5712,6 +5712,7 @@ static int __init mem_cgroup_init(void)
> >>
> >>   rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
> >>   node_online(node) ? node : NUMA_NO_NODE);
> >> + BUG_ON(!rtpn);
> >>
> >>   for (zone = 0; zone < MAX_NR_ZONES; zone++) {
> >>   struct mem_cgroup_tree_per_zone *rtpz;
> >> --
> >> 1.8.3.1
> >>
> >>
> >> --
> >> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> >> the body to majord...@kvack.org.  For more info on Linux MM,
> >> see: http://www.linux-mm.org/ .
> >> Don't email: mailto:"d...@kvack.org;> em...@kvack.org 
> >
> > --
> > Michal Hocko
> > SUSE Labs
> 
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majord...@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: mailto:"d...@kvack.org;> em...@kvack.org 

-- 
Michal Hocko
SUSE Labs

Re: [PATCH] mm/memcontrol.c: add memory allocation result check

[Michal Hocko]

On Mon 30-05-16 17:28:40, Wenwei Tao wrote:
> I think explicit BUG_ON may make the debug easier, since it can point
> out the wrong line.

Does it? NULL ptr dereferencec 6 lines below sounds pretty close to me.
I am not nacking this patch I just think it doesn't add much. If others
think it will be useful I will not object.

> 2016-05-30 16:53 GMT+08:00 Michal Hocko :
> > On Mon 30-05-16 16:45:51, Wenwei Tao wrote:
> >> From: Wenwei Tao 
> >>
> >> The mem_cgroup_tree_per_node allocation might fail,
> >> check that before continue the memcg init. Since it
> >> is in the init phase, trigger the panic if that failure
> >> happens.
> >
> > We would blow up in the very same function so what is the point of the
> > explicit BUG_ON?
> >
> >> Signed-off-by: Wenwei Tao 
> >> ---
> >>  mm/memcontrol.c | 1 +
> >>  1 file changed, 1 insertion(+)
> >>
> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> >> index 925b431..6385c62 100644
> >> --- a/mm/memcontrol.c
> >> +++ b/mm/memcontrol.c
> >> @@ -5712,6 +5712,7 @@ static int __init mem_cgroup_init(void)
> >>
> >>   rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
> >>   node_online(node) ? node : NUMA_NO_NODE);
> >> + BUG_ON(!rtpn);
> >>
> >>   for (zone = 0; zone < MAX_NR_ZONES; zone++) {
> >>   struct mem_cgroup_tree_per_zone *rtpz;
> >> --
> >> 1.8.3.1
> >>
> >>
> >> --
> >> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> >> the body to majord...@kvack.org.  For more info on Linux MM,
> >> see: http://www.linux-mm.org/ .
> >> Don't email: mailto:"d...@kvack.org;> em...@kvack.org 
> >
> > --
> > Michal Hocko
> > SUSE Labs
> 
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majord...@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: mailto:"d...@kvack.org;> em...@kvack.org 

-- 
Michal Hocko
SUSE Labs

Re: [PATCH] mm/memcontrol.c: add memory allocation result check

[Wenwei Tao]

I think explicit BUG_ON may make the debug easier, since it can point
out the wrong line.

2016-05-30 16:53 GMT+08:00 Michal Hocko :
> On Mon 30-05-16 16:45:51, Wenwei Tao wrote:
>> From: Wenwei Tao 
>>
>> The mem_cgroup_tree_per_node allocation might fail,
>> check that before continue the memcg init. Since it
>> is in the init phase, trigger the panic if that failure
>> happens.
>
> We would blow up in the very same function so what is the point of the
> explicit BUG_ON?
>
>> Signed-off-by: Wenwei Tao 
>> ---
>>  mm/memcontrol.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 925b431..6385c62 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -5712,6 +5712,7 @@ static int __init mem_cgroup_init(void)
>>
>>   rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
>>   node_online(node) ? node : NUMA_NO_NODE);
>> + BUG_ON(!rtpn);
>>
>>   for (zone = 0; zone < MAX_NR_ZONES; zone++) {
>>   struct mem_cgroup_tree_per_zone *rtpz;
>> --
>> 1.8.3.1
>>
>>
>> --
>> To unsubscribe, send a message with 'unsubscribe linux-mm' in
>> the body to majord...@kvack.org.  For more info on Linux MM,
>> see: http://www.linux-mm.org/ .
>> Don't email: mailto:"d...@kvack.org;> em...@kvack.org 
>
> --
> Michal Hocko
> SUSE Labs

Re: [PATCH] mm/memcontrol.c: add memory allocation result check

[Wenwei Tao]

I think explicit BUG_ON may make the debug easier, since it can point
out the wrong line.

2016-05-30 16:53 GMT+08:00 Michal Hocko :
> On Mon 30-05-16 16:45:51, Wenwei Tao wrote:
>> From: Wenwei Tao 
>>
>> The mem_cgroup_tree_per_node allocation might fail,
>> check that before continue the memcg init. Since it
>> is in the init phase, trigger the panic if that failure
>> happens.
>
> We would blow up in the very same function so what is the point of the
> explicit BUG_ON?
>
>> Signed-off-by: Wenwei Tao 
>> ---
>>  mm/memcontrol.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 925b431..6385c62 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -5712,6 +5712,7 @@ static int __init mem_cgroup_init(void)
>>
>>   rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
>>   node_online(node) ? node : NUMA_NO_NODE);
>> + BUG_ON(!rtpn);
>>
>>   for (zone = 0; zone < MAX_NR_ZONES; zone++) {
>>   struct mem_cgroup_tree_per_zone *rtpz;
>> --
>> 1.8.3.1
>>
>>
>> --
>> To unsubscribe, send a message with 'unsubscribe linux-mm' in
>> the body to majord...@kvack.org.  For more info on Linux MM,
>> see: http://www.linux-mm.org/ .
>> Don't email: mailto:"d...@kvack.org;> em...@kvack.org 
>
> --
> Michal Hocko
> SUSE Labs

Re: [PATCH] mm/memcontrol.c: add memory allocation result check

[Michal Hocko]

On Mon 30-05-16 16:45:51, Wenwei Tao wrote:
> From: Wenwei Tao 
> 
> The mem_cgroup_tree_per_node allocation might fail,
> check that before continue the memcg init. Since it
> is in the init phase, trigger the panic if that failure
> happens.

We would blow up in the very same function so what is the point of the
explicit BUG_ON?

> Signed-off-by: Wenwei Tao 
> ---
>  mm/memcontrol.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 925b431..6385c62 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -5712,6 +5712,7 @@ static int __init mem_cgroup_init(void)
>  
>   rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
>   node_online(node) ? node : NUMA_NO_NODE);
> + BUG_ON(!rtpn);
>  
>   for (zone = 0; zone < MAX_NR_ZONES; zone++) {
>   struct mem_cgroup_tree_per_zone *rtpz;
> -- 
> 1.8.3.1
> 
> 
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majord...@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: mailto:"d...@kvack.org;> em...@kvack.org 

-- 
Michal Hocko
SUSE Labs

Re: [PATCH] mm/memcontrol.c: add memory allocation result check

[Michal Hocko]

On Mon 30-05-16 16:45:51, Wenwei Tao wrote:
> From: Wenwei Tao 
> 
> The mem_cgroup_tree_per_node allocation might fail,
> check that before continue the memcg init. Since it
> is in the init phase, trigger the panic if that failure
> happens.

We would blow up in the very same function so what is the point of the
explicit BUG_ON?

> Signed-off-by: Wenwei Tao 
> ---
>  mm/memcontrol.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 925b431..6385c62 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -5712,6 +5712,7 @@ static int __init mem_cgroup_init(void)
>  
>   rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
>   node_online(node) ? node : NUMA_NO_NODE);
> + BUG_ON(!rtpn);
>  
>   for (zone = 0; zone < MAX_NR_ZONES; zone++) {
>   struct mem_cgroup_tree_per_zone *rtpz;
> -- 
> 1.8.3.1
> 
> 
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majord...@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: mailto:"d...@kvack.org;> em...@kvack.org 

-- 
Michal Hocko
SUSE Labs

[PATCH] mm/memcontrol.c: add memory allocation result check

[Wenwei Tao]

From: Wenwei Tao 

The mem_cgroup_tree_per_node allocation might fail,
check that before continue the memcg init. Since it
is in the init phase, trigger the panic if that failure
happens.

Signed-off-by: Wenwei Tao 
---
 mm/memcontrol.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 925b431..6385c62 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5712,6 +5712,7 @@ static int __init mem_cgroup_init(void)
 
rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
node_online(node) ? node : NUMA_NO_NODE);
+   BUG_ON(!rtpn);
 
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
struct mem_cgroup_tree_per_zone *rtpz;
-- 
1.8.3.1

[PATCH] mm/memcontrol.c: add memory allocation result check

[Wenwei Tao]

From: Wenwei Tao 

The mem_cgroup_tree_per_node allocation might fail,
check that before continue the memcg init. Since it
is in the init phase, trigger the panic if that failure
happens.

Signed-off-by: Wenwei Tao 
---
 mm/memcontrol.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 925b431..6385c62 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5712,6 +5712,7 @@ static int __init mem_cgroup_init(void)
 
rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
node_online(node) ? node : NUMA_NO_NODE);
+   BUG_ON(!rtpn);
 
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
struct mem_cgroup_tree_per_zone *rtpz;
-- 
1.8.3.1