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Subject: Re: [PATCH] mm/debug: sync up latest migrate_reason to
 migrate_reason_names
To:     "Huang, Ying" <ying.huang@intel.com>,
        John Hubbard <jhubbard@nvidia.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:   Weizhao Ouyang <o451686892@gmail.com>
Message-ID: <89a06743-b37a-b85a-1c04-5d863a1d2cb4@gmail.com>
Date:   Fri, 17 Sep 2021 17:48:53 +0800
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Thank you both.
On 2021/9/17 下午3:03, 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?

How about move migrate_reason_names into mm/page_owner.c and make it size uninitialized(get rid of MR_TYPES).
Then use BUILD_BUG_ON(ARRAY_SIZE(migrate_reason_names != MR_TYPES)) to check it?

>
> Best Regards,
> Huang, Ying