From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757850AbbE3MDu (ORCPT ); Sat, 30 May 2015 08:03:50 -0400 Received: from mail-wi0-f169.google.com ([209.85.212.169]:37344 "EHLO mail-wi0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757807AbbE3MDl (ORCPT ); Sat, 30 May 2015 08:03:41 -0400 From: Jeff Layton X-Google-Original-From: Jeff Layton To: trond.myklebust@primarydata.com Cc: linux-nfs@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Mel Gorman , Jerome Marchand Subject: [PATCH 4/4] sunrpc: lock xprt before trying to set memalloc on the sockets Date: Sat, 30 May 2015 08:03:13 -0400 Message-Id: <1432987393-15604-5-git-send-email-jeff.layton@primarydata.com> X-Mailer: git-send-email 2.4.1 In-Reply-To: <1432987393-15604-1-git-send-email-jeff.layton@primarydata.com> References: <1432987393-15604-1-git-send-email-jeff.layton@primarydata.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index 359446442112..91770ccab608 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) } #ifdef 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); } @@ -1986,8 +1997,11 @@ xs_swapper_enable(struct rpc_xprt *xprt) struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt); + if (wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_KILLABLE)) + return -ERESTARTSYS; if (atomic_inc_return(&xprt->swapper) == 1) sk_set_memalloc(transport->inet); + xprt_release_xprt(xprt, NULL); return 0; } @@ -2004,8 +2018,11 @@ xs_swapper_disable(struct rpc_xprt *xprt) struct sock_xprt *transport = container_of(xprt, struct sock_xprt, xprt); + if (wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE)) + return; if (atomic_dec_and_test(&xprt->swapper)) sk_clear_memalloc(transport->inet); + xprt_release_xprt(xprt, NULL); } #else static void xs_set_memalloc(struct rpc_xprt *xprt) -- 2.4.1