The patch titled
Subject: memory tiering: read last_cpupid correctly in do_huge_pmd_numa_page()
has been added to the -mm mm-unstable branch. Its filename is
memory-tiering-read-last_cpupid-correctly-in-do_huge_pmd_numa_page.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/memory-tiering-read-last_cpupid-correctly-in-do_huge_pmd_numa_page.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Zi Yan <ziy@xxxxxxxxxx>
Subject: memory tiering: read last_cpupid correctly in do_huge_pmd_numa_page()
Date: Mon, 22 Jul 2024 13:29:15 -0400
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.
Link: https://lkml.kernel.org/r/20240722172917.503370-1-ziy@xxxxxxxxxx
Fixes: 33024536bafd ("memory tiering: hot page selection with hint page fault latency")
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Reported-by: David Hildenbrand <david@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-mm/9af34a6b-ca56-4a64-8aa6-ade65f109288@xxxxxxxxxx/
Reviewed-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/mm/huge_memory.c~memory-tiering-read-last_cpupid-correctly-in-do_huge_pmd_numa_page
+++ a/mm/huge_memory.c
@@ -1712,7 +1712,8 @@ vm_fault_t do_huge_pmd_numa_page(struct
* 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)
_
Patches currently in -mm which might be from ziy@xxxxxxxxxx are
memory-tiering-read-last_cpupid-correctly-in-do_huge_pmd_numa_page.patch
memory-tiering-introduce-folio_has_cpupid-check.patch
memory-tiering-count-pgpromote_success-when-mem-tiering-is-enabled.patch
