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Date:   Tue, 12 Dec 2023 08:25:35 -0400
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Mina Almasry <almasrymina@google.com>
Cc:     Shailend Chand <shailend@google.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
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        "David S. Miller" <davem@davemloft.net>,
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        Jesper Dangaard Brouer <hawk@kernel.org>,
        Ilias Apalodimas <ilias.apalodimas@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>,
        David Ahern <dsahern@kernel.org>,
        Willem de Bruijn <willemdebruijn.kernel@gmail.com>,
        Shuah Khan <shuah@kernel.org>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        Christian =?utf-8?B?S8O2bmln?= <christian.koenig@amd.com>,
        Yunsheng Lin <linyunsheng@huawei.com>,
        Harshitha Ramamurthy <hramamurthy@google.com>,
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        Willem de Bruijn <willemb@google.com>,
        Kaiyuan Zhang <kaiyuanz@google.com>,
        Christoph Hellwig <hch@infradead.org>
Subject: Re: [net-next v1 08/16] memory-provider: dmabuf devmem memory
 provider
Message-ID: <20231212122535.GA3029808@nvidia.com>
References: <20231208005250.2910004-1-almasrymina@google.com>
 <20231208005250.2910004-9-almasrymina@google.com>
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On Thu, Dec 07, 2023 at 04:52:39PM -0800, Mina Almasry wrote:

> +static inline struct page_pool_iov *page_to_page_pool_iov(struct page *page)
> +{
> +	if (page_is_page_pool_iov(page))
> +		return (struct page_pool_iov *)((unsigned long)page & ~PP_IOV);
> +
> +	DEBUG_NET_WARN_ON_ONCE(true);
> +	return NULL;
> +}

We already asked not to do this, please do not allocate weird things
can call them 'struct page' when they are not. It undermines the
maintainability of the mm to have things mis-typed like
this. Introduce a new type for your thing so the compiler can check it
properly.

Jason