On 12 Jul 2024, at 21:13, David Hildenbrand wrote:
> On 12.07.24 04:44, 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>
>> ---
>> 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)
>
> Reported-by: ...
Reported-by: David Hildenbrand <david@xxxxxxxxxx>
I suppose your email[1] reports the issue based on code inspection.
> Closes: ...
Closes: https://lore.kernel.org/linux-mm/9af34a6b-ca56-4a64-8aa6-ade65f109288@xxxxxxxxxx/
Will add them in the next version.
>
> If it applies ;)
>
> Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Thanks.
[1] https://lore.kernel.org/linux-mm/9af34a6b-ca56-4a64-8aa6-ade65f109288@xxxxxxxxxx/
--
Best Regards,
Yan, Zi
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