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Date:   Fri, 17 Sep 2021 00:27:43 -0700
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Subject: Re: [PATCH] mm/debug: sync up latest migrate_reason to
 migrate_reason_names
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To:     "Huang, Ying" <ying.huang@intel.com>,
        Weizhao Ouyang <o451686892@gmail.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Pavel Tatashin <pasha.tatashin@soleen.com>,
        Oscar Salvador <osalvador@suse.de>,
        Yang Shi <shy828301@gmail.com>, Zi Yan <ziy@nvidia.com>,
        Dave Hansen <dave.hansen@linux.intel.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
References: <20210917061432.323777-1-o451686892@gmail.com>
 <871r5nptt7.fsf@yhuang6-desk2.ccr.corp.intel.com>
From:   John Hubbard <jhubbard@nvidia.com>
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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