memory_group_register_static takes maximum number of pages as the argument
while dev_dax_kmem_probe passes total_len (in bytes) as the argument.
Signed-off-by: Tarun Sahu <[email protected]>
---
drivers/dax/kmem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
index 7b36db6f1cbd..898ca9505754 100644
--- a/drivers/dax/kmem.c
+++ b/drivers/dax/kmem.c
@@ -99,7 +99,7 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
if (!data->res_name)
goto err_res_name;
- rc = memory_group_register_static(numa_node, total_len);
+ rc = memory_group_register_static(numa_node, PFN_UP(total_len));
if (rc < 0)
goto err_reg_mgid;
data->mgid = rc;
--
2.31.1
On Tue, Jun 20, 2023 at 07:33:32PM +0530, Tarun Sahu wrote:
> memory_group_register_static takes maximum number of pages as the argument
> while dev_dax_kmem_probe passes total_len (in bytes) as the argument.
This sounds like a fix. An explanation of the impact and a fixes tag
may be needed. Also, wondering how you found it.
Alison
>
> Signed-off-by: Tarun Sahu <[email protected]>
> ---
> drivers/dax/kmem.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
> index 7b36db6f1cbd..898ca9505754 100644
> --- a/drivers/dax/kmem.c
> +++ b/drivers/dax/kmem.c
> @@ -99,7 +99,7 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
> if (!data->res_name)
> goto err_res_name;
>
> - rc = memory_group_register_static(numa_node, total_len);
> + rc = memory_group_register_static(numa_node, PFN_UP(total_len));
> if (rc < 0)
> goto err_reg_mgid;
> data->mgid = rc;
> --
> 2.31.1
>
Hi Alison,
Alison Schofield <[email protected]> writes:
> On Tue, Jun 20, 2023 at 07:33:32PM +0530, Tarun Sahu wrote:
>> memory_group_register_static takes maximum number of pages as the argument
>> while dev_dax_kmem_probe passes total_len (in bytes) as the argument.
>
> This sounds like a fix. An explanation of the impact and a fixes tag
> may be needed. Also, wondering how you found it.
>
Yes, it is a fix, I found it during dry code walk-through.
There is not any impact as such. As,
memory_group_register_static just set the max_pages limit which
is used in auto_movable_zone_for_pfn to determine the zone.
which might cause these condition to behave differently,
This will be true always so jump will happen to kernel_zone
if (!auto_movable_can_online_movable(NUMA_NO_NODE, group, nr_pages))
goto kernel_zone;
---
kernel_zone:
return default_kernel_zone_for_pfn(nid, pfn, nr_pages);
---
Here, In below, zone_intersects compare range will be larger as nr_pages
will be higher (derived from total_len passed in dev_dax_kmem_probe).
static struct zone *default_kernel_zone_for_pfn(int nid, unsigned long start_pfn,
unsigned long nr_pages)
{
struct pglist_data *pgdat = NODE_DATA(nid);
int zid;
for (zid = 0; zid < ZONE_NORMAL; zid++) {
struct zone *zone = &pgdat->node_zones[zid];
if (zone_intersects(zone, start_pfn, nr_pages))
return zone;
}
return &pgdat->node_zones[ZONE_NORMAL];
}
In Mostly cases, ZONE_NORMAL will be returned. But there is no
crash/panic issues involved here, only decision making on selecting zone
is affected.
> Alison
>
>>
>> Signed-off-by: Tarun Sahu <[email protected]>
>> ---
>> drivers/dax/kmem.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c
>> index 7b36db6f1cbd..898ca9505754 100644
>> --- a/drivers/dax/kmem.c
>> +++ b/drivers/dax/kmem.c
>> @@ -99,7 +99,7 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
>> if (!data->res_name)
>> goto err_res_name;
>>
>> - rc = memory_group_register_static(numa_node, total_len);
>> + rc = memory_group_register_static(numa_node, PFN_UP(total_len));
>> if (rc < 0)
>> goto err_reg_mgid;
>> data->mgid = rc;
>> --
>> 2.31.1
>>
On Wed, 2023-06-21 at 11:36 +0530, Tarun Sahu wrote:
> Hi Alison,
>
> Alison Schofield <[email protected]> writes:
>
> > On Tue, Jun 20, 2023 at 07:33:32PM +0530, Tarun Sahu wrote:
> > > memory_group_register_static takes maximum number of pages as the argument
> > > while dev_dax_kmem_probe passes total_len (in bytes) as the argument.
> >
> > This sounds like a fix. An explanation of the impact and a fixes tag
> > may be needed. Also, wondering how you found it.
> >
> Yes, it is a fix, I found it during dry code walk-through.
> There is not any impact as such. As,
> memory_group_register_static just set the max_pages limit which
> is used in auto_movable_zone_for_pfn to determine the zone.
>
> which might cause these condition to behave differently,
>
> This will be true always so jump will happen to kernel_zone
> if (!auto_movable_can_online_movable(NUMA_NO_NODE, group, nr_pages))
> goto kernel_zone;
> ---
> kernel_zone:
> return default_kernel_zone_for_pfn(nid, pfn, nr_pages);
>
> ---
>
> Here, In below, zone_intersects compare range will be larger as nr_pages
> will be higher (derived from total_len passed in dev_dax_kmem_probe).
>
> static struct zone *default_kernel_zone_for_pfn(int nid, unsigned long start_pfn,
> unsigned long nr_pages)
> {
> struct pglist_data *pgdat = NODE_DATA(nid);
> int zid;
>
> for (zid = 0; zid < ZONE_NORMAL; zid++) {
> struct zone *zone = &pgdat->node_zones[zid];
>
> if (zone_intersects(zone, start_pfn, nr_pages))
> return zone;
> }
>
> return &pgdat->node_zones[ZONE_NORMAL];
> }
>
> In Mostly cases, ZONE_NORMAL will be returned. But there is no
> crash/panic issues involved here, only decision making on selecting zone
> is affected.
>
Hi Tarun,
Good find! With a Fixes tag, and perhaps inclusion of a bit more of
this detail described in the commit message, feel free to add:
Reviewed-by: Vishal Verma <[email protected]>
Hi Vishal,
"Verma, Vishal L" <[email protected]> writes:
> On Wed, 2023-06-21 at 11:36 +0530, Tarun Sahu wrote:
>> Hi Alison,
>>
>> Alison Schofield <[email protected]> writes:
>>
>> > On Tue, Jun 20, 2023 at 07:33:32PM +0530, Tarun Sahu wrote:
>> > > memory_group_register_static takes maximum number of pages as the argument
>> > > while dev_dax_kmem_probe passes total_len (in bytes) as the argument.
>> >
>> > This sounds like a fix. An explanation of the impact and a fixes tag
>> > may be needed. Also, wondering how you found it.
>> >
>> Yes, it is a fix, I found it during dry code walk-through.
>> There is not any impact as such. As,
>> memory_group_register_static just set the max_pages limit which
>> is used in auto_movable_zone_for_pfn to determine the zone.
>>
>> which might cause these condition to behave differently,
>>
>> This will be true always so jump will happen to kernel_zone
>> if (!auto_movable_can_online_movable(NUMA_NO_NODE, group, nr_pages))
>> goto kernel_zone;
>> ---
>> kernel_zone:
>> return default_kernel_zone_for_pfn(nid, pfn, nr_pages);
>>
>> ---
>>
>> Here, In below, zone_intersects compare range will be larger as nr_pages
>> will be higher (derived from total_len passed in dev_dax_kmem_probe).
>>
>> static struct zone *default_kernel_zone_for_pfn(int nid, unsigned long start_pfn,
>> unsigned long nr_pages)
>> {
>> struct pglist_data *pgdat = NODE_DATA(nid);
>> int zid;
>>
>> for (zid = 0; zid < ZONE_NORMAL; zid++) {
>> struct zone *zone = &pgdat->node_zones[zid];
>>
>> if (zone_intersects(zone, start_pfn, nr_pages))
>> return zone;
>> }
>>
>> return &pgdat->node_zones[ZONE_NORMAL];
>> }
>>
>> In Mostly cases, ZONE_NORMAL will be returned. But there is no
>> crash/panic issues involved here, only decision making on selecting zone
>> is affected.
>>
>
> Hi Tarun,
>
> Good find! With a Fixes tag, and perhaps inclusion of a bit more of
> this detail described in the commit message, feel free to add:
>
Thanks for reviewing, sent the updated version.
> Reviewed-by: Vishal Verma <[email protected]>