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From:   Olga Kornievskaia <aglo@umich.edu>
Date:   Mon, 30 Nov 2020 14:33:04 -0500
Message-ID: <CAN-5tyFP6F1Q+gGBLwfwazuaw7WYu-UGfd=Bb0nOmxgU0e_uxw@mail.gmail.com>
Subject: Re: [PATCH v1] SUNRPC: Remove XDRBUF_SPARSE_PAGES flag in gss_proxy upcall
To:     Chuck Lever <chuck.lever@oracle.com>
Cc:     linux-nfs <linux-nfs@vger.kernel.org>,
        Trond Myklebust <trond.myklebust@primarydata.com>,
        Simo Sorce <simo@redhat.com>,
        "J. Bruce Fields" <bfields@fieldses.org>
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On Tue, Nov 24, 2020 at 7:04 PM Chuck Lever <chuck.lever@oracle.com> wrote:
>
> Commit 9dfd87da1aeb ("rpc: fix huge kmalloc's in gss-proxy") added
> gssp_alloc_receive_pages() to fully allocate the receive buffer
> for gss_proxy upcalls.
>
> However, later, 431f6eb3570f ("SUNRPC: Add a label for RPC calls
> that require allocation on receive") sets the XDRBUF_SPARSE_PAGES
> flag for this receive buffer anyway. That doesn't appear to have
> been necessary, since gssp_alloc_receive_pages() still exists.

But the gssp_alloc_receive_pages() only allocates the array of page
pointers not the actual pages, so I believe the flag is still needed
to have those pages allocated by something? What is allocating those
pages if not the SPARSE_PAGES method, what am I missing?


> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>  net/sunrpc/auth_gss/gss_rpc_xdr.c |    1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/net/sunrpc/auth_gss/gss_rpc_xdr.c b/net/sunrpc/auth_gss/gss_rpc_xdr.c
> index 2ff7b7083eba..44838f6ea25e 100644
> --- a/net/sunrpc/auth_gss/gss_rpc_xdr.c
> +++ b/net/sunrpc/auth_gss/gss_rpc_xdr.c
> @@ -771,7 +771,6 @@ void gssx_enc_accept_sec_context(struct rpc_rqst *req,
>         xdr_inline_pages(&req->rq_rcv_buf,
>                 PAGE_SIZE/2 /* pretty arbitrary */,
>                 arg->pages, 0 /* page base */, arg->npages * PAGE_SIZE);
> -       req->rq_rcv_buf.flags |= XDRBUF_SPARSE_PAGES;
>  done:
>         if (err)
>                 dprintk("RPC:       gssx_enc_accept_sec_context: %d\n", err);
>
>