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Date:   Mon, 17 May 2021 16:30:44 +0100
From:   Mel Gorman <mgorman@suse.de>
To:     Yang Shi <shy828301@gmail.com>
Cc:     kirill.shutemov@linux.intel.com, ziy@nvidia.com, mhocko@suse.com,
        ying.huang@intel.com, hughd@google.com,
        gerald.schaefer@linux.ibm.com, hca@linux.ibm.com,
        gor@linux.ibm.com, borntraeger@de.ibm.com,
        akpm@linux-foundation.org, linux-mm@kvack.org,
        linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [v2 PATCH 7/7] mm: thp: skip make PMD PROT_NONE if THP migration
 is not supported
Message-ID: <20210517153044.GZ3672@suse.de>
References: <20210413212416.3273-1-shy828301@gmail.com>
 <20210413212416.3273-8-shy828301@gmail.com>
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On Tue, Apr 13, 2021 at 02:24:16PM -0700, Yang Shi wrote:
> A quick grep shows x86_64, PowerPC (book3s), ARM64 and S390 support both
> NUMA balancing and THP.  But S390 doesn't support THP migration so NUMA
> balancing actually can't migrate any misplaced pages.
> 
> Skip make PMD PROT_NONE for such case otherwise CPU cycles may be wasted
> by pointless NUMA hinting faults on S390.
> 
> Signed-off-by: Yang Shi <shy828301@gmail.com>

Acked-by: Mel Gorman <mgorman@suse.de>

-- 
Mel Gorman
SUSE Labs