linux-kernel - Re: [PATCH 1/1] infiniband/mm: convert put_page() to put_user

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Message-ID: <708b9fc4-9afd-345e-83f7-2ceae673a4fd@nvidia.com>
Date:   Thu, 23 May 2019 10:56:56 -0700
From:   John Hubbard <jhubbard@...dia.com>
To:     Jerome Glisse <jglisse@...hat.com>
CC:     Andrew Morton <akpm@...ux-foundation.org>, <linux-mm@...ck.org>,
        "Jason Gunthorpe" <jgg@...pe.ca>,
        LKML <linux-kernel@...r.kernel.org>,
        <linux-rdma@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>,
        Doug Ledford <dledford@...hat.com>,
        Mike Marciniszyn <mike.marciniszyn@...el.com>,
        "Dennis Dalessandro" <dennis.dalessandro@...el.com>,
        Christian Benvenuti <benve@...co.com>, Jan Kara <jack@...e.cz>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Ira Weiny <ira.weiny@...el.com>
Subject: Re: [PATCH 1/1] infiniband/mm: convert put_page() to put_user_page*()

On 5/23/19 8:31 AM, Jerome Glisse wrote:
[...]
> 
> Reviewed-by: Jérôme Glisse <jglisse@...hat.com>
> 

Thanks for the review!

> Between i have a wishlist see below
[...]
>> diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
>> index e7ea819fcb11..673f0d240b3e 100644
>> --- a/drivers/infiniband/core/umem.c
>> +++ b/drivers/infiniband/core/umem.c
>> @@ -54,9 +54,10 @@ static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int d
>>   
>>   	for_each_sg_page(umem->sg_head.sgl, &sg_iter, umem->sg_nents, 0) {
>>   		page = sg_page_iter_page(&sg_iter);
>> -		if (!PageDirty(page) && umem->writable && dirty)
>> -			set_page_dirty_lock(page);
>> -		put_page(page);
>> +		if (umem->writable && dirty)
>> +			put_user_pages_dirty_lock(&page, 1);
>> +		else
>> +			put_user_page(page);
> 
> Can we get a put_user_page_dirty(struct page 8*pages, bool dirty, npages) ?
> 
> It is a common pattern that we might have to conditionaly dirty the pages
> and i feel it would look cleaner if we could move the branch within the
> put_user_page*() function.
> 

This sounds reasonable to me, do others have a preference on this? Last time
we discussed it, I recall there was interest in trying to handle the sg lists,
which was where a lot of focus was. I'm not sure if there was a preference one 
way or the other, on adding more of these helpers.


thanks,
-- 
John Hubbard
NVIDIA