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

[John Hubbard <jhubbard@nvidia.com>]

On 9/17/21 00:03, Huang, Ying wrote:
> Weizhao Ouyang <o451686892@gmail.com> writes:
> 
>> After related migrate page updates, sync up latest migrate_reason to
>> migrate_reason_names, page_owner use it to parse the page migrate
>> reason.
>>
>> Fixes: d1e153fea2a8 ("mm/gup: migrate pinned pages out of movable zone")
>> Fixes: 26aa2d199d6f ("mm/migrate: demote pages during reclaim")
>> Signed-off-by: Weizhao Ouyang <o451686892@gmail.com>
>> ---
>>   mm/debug.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/mm/debug.c b/mm/debug.c
>> index e73fe0a8ec3d..733770b0ed0c 100644
>> --- a/mm/debug.c
>> +++ b/mm/debug.c
>> @@ -25,6 +25,8 @@ const char *migrate_reason_names[MR_TYPES] = {
>>   	"mempolicy_mbind",
>>   	"numa_misplaced",
>>   	"cma",
>> +	"longterm_pin",
>> +	"demotion",
>>   };
>>   
>>   const struct trace_print_flags pageflag_names[] = {
> 
> Good catch!  Thanks!
> 
> Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
> 
> It may be better to use BUILD_BUG_ON() to capture similar issue earlier?

Yes! Or if BUILD_BUG_ON() can't work here, then at least a comment in the
various locations, explaining that these must be kept in sync. But
BUILD_BUG_ON() should work, I think.


thanks,
-- 
John Hubbard
NVIDIA