From 7d4194abfc4de13a2663c7fee6891de8360f7a52 Mon Sep 17 00:00:00 2001
From: Coly Li <colyli@suse.de>
Date: Fri, 2 Oct 2020 16:27:30 +0800
Subject: [PATCH] nvme-tcp: check page by sendpage_ok() before calling
 kernel_sendpage()
Git-commit: 7d4194abfc4de13a2663c7fee6891de8360f7a52
Patch-mainline: v5.9
References: bsc#1172873

Currently nvme_tcp_try_send_data() doesn't use kernel_sendpage() to
send slab pages. But for pages allocated by __get_free_pages() without
__GFP_COMP, which also have refcount as 0, they are still sent by
kernel_sendpage() to remote end, this is problematic.

The new introduced helper sendpage_ok() checks both PageSlab tag and
page_count counter, and returns true if the checking page is OK to be
sent by kernel_sendpage().

This patch fixes the page checking issue of nvme_tcp_try_send_data()
with sendpage_ok(). If sendpage_ok() returns true, send this page by
kernel_sendpage(), otherwise use sock_no_sendpage to handle this page.

(Coly Li: rebase for 4.12 based SUSE kernel)

Signed-off-by: Coly Li <colyli@suse.de>
Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Jan Kara <jack@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Mikhail Skorzhinskii <mskorzhinskiy@solarflare.com>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Vlastimil Babka <vbabka@suse.com>
Cc: stable@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

---
 drivers/nvme/host/tcp.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -861,7 +861,13 @@ static int nvme_tcp_try_send_data(struct
 		else
 			flags |= MSG_MORE;
 
-		ret = kernel_sendpage(queue->sock, page, offset, len, flags);
+		if (sendpage_ok(page)) {
+			ret = kernel_sendpage(queue->sock, page, offset, len,
+					flags);
+		} else {
+			ret = sock_no_sendpage(queue->sock, page, offset, len,
+					flags);
+		}
 		if (ret <= 0)
 			return ret;