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Subject: Re: [RFC PATCH v1 13/13] mm: splice local lists onto the front of the
 LRU
To:     Laurent Dufour <ldufour@linux.vnet.ibm.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Cc:     aaron.lu@intel.com, ak@linux.intel.com, akpm@linux-foundation.org,
        Dave.Dice@oracle.com, dave@stgolabs.net,
        khandual@linux.vnet.ibm.com, mgorman@suse.de, mhocko@kernel.org,
        pasha.tatashin@oracle.com, steven.sistare@oracle.com,
        yossi.lev@oracle.com
References: <20180131230413.27653-1-daniel.m.jordan@oracle.com>
 <20180131230413.27653-14-daniel.m.jordan@oracle.com>
 <765238a2-8970-e05d-4fe3-cdcb796aa399@linux.vnet.ibm.com>
From:   Daniel Jordan <daniel.m.jordan@oracle.com>
Organization: Oracle Corporation
Message-ID: <a9518500-cc2a-ce15-76a4-73a31b744852@oracle.com>
Date:   Tue, 6 Feb 2018 13:18:53 -0500
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On 02/02/2018 10:22 AM, Laurent Dufour wrote:
> On 01/02/2018 00:04, daniel.m.jordan@oracle.com wrote:
...snip...
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 99a54df760e3..6911626f29b2 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -2077,6 +2077,7 @@ static void lock_page_lru(struct page *page, int *isolated)
>>
>>   		lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat);
>>   		ClearPageLRU(page);
>> +		smp_rmb(); /* Pairs with smp_wmb in __pagevec_lru_add */
> 
> Why not include the call to smp_rmb() in del_page_from_lru_list() instead
> of spreading smp_rmb() before calls to del_page_from_lru_list() ?

Yes, this is what I should have done.  The memory barriers came from 
another patch I squashed in and I didn't look back to see how obvious 
the encapsulation was.