linux-kernel - [PATCH AUTOSEL for 4.14 40/60] sctp: silence warns on sctp_stream

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Date:   Wed, 13 Dec 2017 01:55:21 +0000
From:   alexander.levin@...izon.com
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        alexander.levin@...izon.com
Subject: [PATCH AUTOSEL for 4.14 40/60] sctp: silence warns on
 sctp_stream_init allocations

From: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>

[ Upstream commit 1ae2eaaa229bc350b6f38fbf4ab9c873532aecfb ]

As SCTP supports up to 65535 streams, that can lead to very large
allocations in sctp_stream_init(). As Xin Long noticed, systems with
small amounts of memory are more prone to not have enough memory and
dump warnings on dmesg initiated by user actions. Thus, silence them.

Also, if the reallocation of stream->out is not necessary, skip it and
keep the memory we already have.

Reported-by: Xin Long <lucien.xin@...il.com>
Tested-by: Xin Long <lucien.xin@...il.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 net/sctp/stream.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/net/sctp/stream.c b/net/sctp/stream.c
index fa8371ff05c4..724adf2786a2 100644
--- a/net/sctp/stream.c
+++ b/net/sctp/stream.c
@@ -40,9 +40,14 @@ int sctp_stream_init(struct sctp_stream *stream, __u16 outcnt, __u16 incnt,
 {
 	int i;
 
+	gfp |= __GFP_NOWARN;
+
 	/* Initial stream->out size may be very big, so free it and alloc
-	 * a new one with new outcnt to save memory.
+	 * a new one with new outcnt to save memory if needed.
 	 */
+	if (outcnt == stream->outcnt)
+		goto in;
+
 	kfree(stream->out);
 
 	stream->out = kcalloc(outcnt, sizeof(*stream->out), gfp);
@@ -53,6 +58,7 @@ int sctp_stream_init(struct sctp_stream *stream, __u16 outcnt, __u16 incnt,
 	for (i = 0; i < stream->outcnt; i++)
 		stream->out[i].state = SCTP_STREAM_OPEN;
 
+in:
 	if (!incnt)
 		return 0;
 
-- 
2.11.0