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Subject: Re: [PATCH 1/1] net/rds: Track user mapped pages through special API
To:     John Hubbard <jhubbard@nvidia.com>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     Hans Westgaard Ry <hans.westgaard.ry@oracle.com>,
        Leon Romanovsky <leonro@mellanox.com>,
        "David S . Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, netdev@vger.kernel.org,
        rds-devel@oss.oracle.com, linux-rdma@vger.kernel.org,
        linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
References: <20200212030355.1600749-1-jhubbard@nvidia.com>
 <20200212030355.1600749-2-jhubbard@nvidia.com>
From:   santosh.shilimkar@oracle.com
Organization: Oracle Corporation
Message-ID: <c0d8d04e-08d1-60ff-ea4c-e6c71f3e118a@oracle.com>
Date:   Wed, 12 Feb 2020 09:31:51 -0800
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On 2/11/20 7:03 PM, John Hubbard wrote:
> From: Leon Romanovsky <leonro@mellanox.com>
> 
> Convert net/rds to use the newly introduces pin_user_pages() API,
> which properly sets FOLL_PIN. Setting FOLL_PIN is now required for
> code that requires tracking of pinned pages.
> 
> Note that this effectively changes the code's behavior: it now
> ultimately calls set_page_dirty_lock(), instead of set_page_dirty().
> This is probably more accurate.
> 
> As Christoph Hellwig put it, "set_page_dirty() is only safe if we are
> dealing with a file backed page where we have reference on the inode it
> hangs off." [1]
> 
> [1] https://urldefense.com/v3/__https://lore.kernel.org/r/20190723153640.GB720@lst.de__;!!GqivPVa7Brio!OJHuecs9Iup5ig3kQBi_423uMMuskWhBQAdOICrY3UQ_ZfEaxt9ySY7E8y32Q7pk5tByyA$
> 
> Cc: Hans Westgaard Ry <hans.westgaard.ry@oracle.com>
> Cc: Santosh Shilimkar <santosh.shilimkar@oracle.com>
> Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>
> ---
Change looks fine to me. Just on safer side, we will try
to test this change with regression suite to make sure it
works as expected.

For patch itself,

Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>