From: Tarun Sahu tsahu@linux.ibm.com
[ Upstream commit 46e66dab8565f742374e9cc4ff7d35f344d774e2 ]
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 tsahu@linux.ibm.com Link: https://lore.kernel.org/r/20230621155025.370672-1-tsahu@linux.ibm.com Reviewed-by: Vishal Verma vishal.l.verma@intel.com Signed-off-by: Vishal Verma vishal.l.verma@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 7b36db6f1cbdc..898ca95057547 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;