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Subject: Re: [PATCH] s390x/mm: avoid taking the table lock in
 gmap_pmd_op_walk()
To:     Janosch Frank <frankja@linux.ibm.com>, linux-kernel@vger.kernel.org
Cc:     linux-s390@vger.kernel.org,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Cornelia Huck <cohuck@redhat.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>
References: <20180806155407.15252-1-david@redhat.com>
 <d3e543bc-d0ff-c8ef-f097-eeba2bde6971@linux.ibm.com>
From:   David Hildenbrand <david@redhat.com>
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Organization: Red Hat GmbH
Message-ID: <85e72251-fa72-9a3f-e2b0-6bc7d9482908@redhat.com>
Date:   Tue, 7 Aug 2018 10:35:56 +0200
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On 07.08.2018 09:26, Janosch Frank wrote:
> On 06.08.2018 17:54, David Hildenbrand wrote:
>> Right now we temporarily take the page table lock in gmap_pmd_op_walk()
>> even though we know we won't need it (if we can never have 1mb pages
>> mapped into the gmap).
>>
>> So let's special case this, so
>> gmap_protect_range()/gmap_sync_dirty_log_pmd() will not take the lock in
>> case huge pages are not allowed.
> 
> So, let's make this a special case
> 
>>
>> gmap_protect_range() is called quite frequently for managing shadow
>> page tables in vSIE environments.
>>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
> 
> If you make the patch title more specific:
> Reviewed-by: Janosch Frank <frankja@linux.ibm.com>


"s390/mm: optimize locking without huge pages in gmap_pmd_op_walk()"

Thanks!

-- 

Thanks,

David / dhildenb