From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f181.google.com (mail-ie0-f181.google.com [209.85.223.181]) by kanga.kvack.org (Postfix) with ESMTP id 05859900016 for ; Wed, 3 Jun 2015 16:14:47 -0400 (EDT) Received: by iesa3 with SMTP id a3so21845510ies.2 for ; Wed, 03 Jun 2015 13:14:46 -0700 (PDT) Received: from mail-ig0-f180.google.com (mail-ig0-f180.google.com. [209.85.213.180]) by mx.google.com with ESMTPS id b18si14534324igr.17.2015.06.03.13.14.46 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 03 Jun 2015 13:14:46 -0700 (PDT) Received: by igblz2 with SMTP id lz2so23751574igb.1 for ; Wed, 03 Jun 2015 13:14:46 -0700 (PDT) From: Jeff Layton Subject: [PATCH v3 4/5] sunrpc: lock xprt before trying to set memalloc on the sockets Date: Wed, 3 Jun 2015 16:14:28 -0400 Message-Id: <1433362469-2615-5-git-send-email-jeff.layton@primarydata.com> In-Reply-To: <1433362469-2615-1-git-send-email-jeff.layton@primarydata.com> References: <1433362469-2615-1-git-send-email-jeff.layton@primarydata.com> Sender: owner-linux-mm@kvack.org List-ID: To: Trond Myklebust Cc: linux-nfs@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman , Jerome Marchand , Chuck Lever It's possible that we could race with a call to xs_reset_transport, in which case the xprt->inet pointer could be zeroed out while we're accessing it. Lock the xprt before we try to set memalloc on it. Cc: Mel Gorman Signed-off-by: Jeff Layton --- net/sunrpc/xprtsock.c | 35 +++++++++++++++++++++++++++-------- 1 file changed, 27 insertions(+), 8 deletions(-) diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index cb928ae4e8f4..e3596fe184a0 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -1964,11 +1964,22 @@ static void xs_local_connect(struct rpc_xprt *xprt, struct rpc_task *task) } #if IS_ENABLED(CONFIG_SUNRPC_SWAP) +/* + * Note that this should be called with XPRT_LOCKED held (or when we otherwise + * know that we have exclusive access to the socket), to guard against + * races with xs_reset_transport. + */ static void xs_set_memalloc(struct rpc_xprt *xprt) { struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt); + /* + * If there's no sock, then we have nothing to set. The + * reconnecting process will get it for us. + */ + if (!transport->inet) + return; if (atomic_read(&xprt->swapper)) sk_set_memalloc(transport->inet); } @@ -1983,11 +1994,15 @@ static void xs_set_memalloc(struct rpc_xprt *xprt) int xs_swapper_enable(struct rpc_xprt *xprt) { - struct sock_xprt *transport = container_of(xprt, struct sock_xprt, - xprt); + struct sock_xprt *xs = container_of(xprt, struct sock_xprt, xprt); - if (atomic_inc_return(&xprt->swapper) == 1) - sk_set_memalloc(transport->inet); + if (atomic_inc_return(&xprt->swapper) != 1) + return 0; + if (wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_KILLABLE)) + return -ERESTARTSYS; + if (xs->inet) + sk_set_memalloc(xs->inet); + xprt_release_xprt(xprt, NULL); return 0; } @@ -2001,11 +2016,15 @@ xs_swapper_enable(struct rpc_xprt *xprt) void xs_swapper_disable(struct rpc_xprt *xprt) { - struct sock_xprt *transport = container_of(xprt, struct sock_xprt, - xprt); + struct sock_xprt *xs = container_of(xprt, struct sock_xprt, xprt); - if (atomic_dec_and_test(&xprt->swapper)) - sk_clear_memalloc(transport->inet); + if (!atomic_dec_and_test(&xprt->swapper)) + return; + if (wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_KILLABLE)) + return; + if (xs->inet) + sk_clear_memalloc(xs->inet); + xprt_release_xprt(xprt, NULL); } #else static void xs_set_memalloc(struct rpc_xprt *xprt) -- 2.4.2 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org