Hi Alison,
Alison Schofield <alison.schofi...@intel.com> 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 <ts...@linux.ibm.com>
>> ---
>> 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
>>
