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.
IIUC, I don't see any crash/panic 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];
}
Incorrect zone will be returned here, which in later time might cause bigger
problem.
Fixes: eedf634aac3b ("dax/kmem: use a single static memory group for a single probed unit")
Signed-off-by: Tarun Sahu <[email protected]>
Reviewed-by: Vishal Verma <[email protected]>
---
V3<-V2
1. Removed skip characters.
V2<-V1
1. Added more details to commit message
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,
This is just a gentle reminder, If any other information is needed.
Tarun Sahu <[email protected]> writes:
> 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.
>
> IIUC, I don't see any crash/panic 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];
> }
>
> Incorrect zone will be returned here, which in later time might cause bigger
> problem.
>
> Fixes: eedf634aac3b ("dax/kmem: use a single static memory group for a single probed unit")
> Signed-off-by: Tarun Sahu <[email protected]>
> Reviewed-by: Vishal Verma <[email protected]>
> ---
> V3<-V2
> 1. Removed skip characters.
>
> V2<-V1
> 1. Added more details to commit message
>
>
> 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
~Tarun