linux-kernel - [PATCH 4.8 62/92] svcrdma: Skip put_page() when send

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Message-Id: <20161117103226.876903315@linuxfoundation.org>
Date:   Thu, 17 Nov 2016 11:32:35 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Chuck Lever <chuck.lever@...cle.com>,
        "J. Bruce Fields" <bfields@...hat.com>
Subject: [PATCH 4.8 62/92] svcrdma: Skip put_page() when send_reply() fails

4.8-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chuck Lever <chuck.lever@...cle.com>

commit 9995237bba702281e0e8e677edd5bb225f4f6c30 upstream.

Message from syslogd@...mt at Aug 18 17:00:37 ...
 kernel:page:ffffea0020639b00 count:0 mapcount:0 mapping:          (null) index:0x0
Aug 18 17:00:37 klimt kernel: flags: 0x2fffff80000000()
Aug 18 17:00:37 klimt kernel: page dumped because: VM_BUG_ON_PAGE(page_ref_count(page) == 0)

Aug 18 17:00:37 klimt kernel: kernel BUG at /home/cel/src/linux/linux-2.6/include/linux/mm.h:445!
Aug 18 17:00:37 klimt kernel: RIP: 0010:[<ffffffffa05c21c1>] svc_rdma_sendto+0x641/0x820 [rpcrdma]

send_reply() assigns its page argument as the first page of ctxt. On
error, send_reply() already invokes svc_rdma_put_context(ctxt, 1);
which does a put_page() on that very page. No need to do that again
as svc_rdma_sendto exits.

Fixes: 3e1eeb980822 ("svcrdma: Close connection when a send error occurs")
Signed-off-by: Chuck Lever <chuck.lever@...cle.com>
Signed-off-by: J. Bruce Fields <bfields@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/sunrpc/xprtrdma/svc_rdma_sendto.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -635,7 +635,7 @@ int svc_rdma_sendto(struct svc_rqst *rqs
 	ret = send_reply(rdma, rqstp, res_page, rdma_resp, vec,
 			 inline_bytes);
 	if (ret < 0)
-		goto err1;
+		goto err0;

 	svc_rdma_put_req_map(rdma, vec);
 	dprintk("svcrdma: send_reply returns %d\n", ret);