On 2024/7/12 10:44, Zi Yan wrote:
From: Zi Yan <ziy@xxxxxxxxxx>
last_cpupid is only available when memory tiering is off or the folio
is in toptier node. Complete the check to read last_cpupid when it is
available.
Before the fix, the default last_cpupid will be used even if memory
tiering mode is turned off at runtime instead of the actual value. This
can prevent task_numa_fault() from getting right numa fault stats, but
should not cause any crash. User might see performance changes after the
fix.
Fixes: 33024536bafd ("memory tiering: hot page selection with hint page fault latency")
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
LGTM.
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index d7c84480f1a4..07d9dde4ca33 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1705,7 +1705,8 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf)
* For memory tiering mode, cpupid of slow memory page is used
* to record page access time. So use default value.
*/
- if (node_is_toptier(nid))
+ if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) ||
+ node_is_toptier(nid))
last_cpupid = folio_last_cpupid(folio);
target_nid = numa_migrate_prep(folio, vmf, haddr, nid, &flags);
if (target_nid == NUMA_NO_NODE)
