Re: [PATCH v2 2/2] mm/debug: sync up latest migrate_reason to migrate_reason_names

[Weizhao Ouyang]

On 2021/9/21 15:07, Huang, Ying wrote:
> Weizhao Ouyang <o451686892@xxxxxxxxx> writes:
>
>> Sync up MR_DEMOTION to migrate_reason_names and add a synch prompt.
>>
>> Fixes: 26aa2d199d6f ("mm/migrate: demote pages during reclaim")
>> Signed-off-by: Weizhao Ouyang <o451686892@xxxxxxxxx>
>> Reviewed-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
>> ---
>>  include/linux/migrate.h | 6 +++++-
>>  mm/debug.c              | 1 +
>>  2 files changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/migrate.h b/include/linux/migrate.h
>> index 326250996b4e..c8077e936691 100644
>> --- a/include/linux/migrate.h
>> +++ b/include/linux/migrate.h
>> @@ -19,6 +19,11 @@ struct migration_target_control;
>>   */
>>  #define MIGRATEPAGE_SUCCESS		0
>>  
>> +/*
>> + * Keep sync with:
>> + * - macro MIGRATE_REASON in include/trace/events/migrate.h
>> + * - migrate_reason_names[MR_TYPES] in mm/debug.c
>> + */
>>  enum migrate_reason {
>>  	MR_COMPACTION,
>>  	MR_MEMORY_FAILURE,
>> @@ -32,7 +37,6 @@ enum migrate_reason {
>>  	MR_TYPES
>>  };
>>  
>> -/* In mm/debug.c; also keep sync with include/trace/events/migrate.h */
>>  extern const char *migrate_reason_names[MR_TYPES];
>>  
>>  #ifdef CONFIG_MIGRATION
>> diff --git a/mm/debug.c b/mm/debug.c
>> index e61037cded98..fae0f81ad831 100644
>> --- a/mm/debug.c
>> +++ b/mm/debug.c
>> @@ -26,6 +26,7 @@ const char *migrate_reason_names[MR_TYPES] = {
>>  	"numa_misplaced",
>>  	"contig_range",
>>  	"longterm_pin",
>> +	"demotion",
>>  };
>>  
>>  const struct trace_print_flags pageflag_names[] = {
> Can we add BUILD_BUG_ON() somewhere to capture at least some
> synchronization issue?

Hi Huang, we discussed this in the v1 thread with you and John, seems you
missed it. Now we just add a comment to do the synchronization, and we can
figure out a more general way to use strings which in trace_events straight.

Thanks,
Weizhao