From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53EDEC433EF for ; Mon, 18 Apr 2022 14:11:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245728AbiDROO3 (ORCPT ); Mon, 18 Apr 2022 10:14:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51740 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245681AbiDROMW (ORCPT ); Mon, 18 Apr 2022 10:12:22 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 294AC38196; Mon, 18 Apr 2022 06:11:45 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id B863E60EFC; Mon, 18 Apr 2022 13:11:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BD37EC385A7; Mon, 18 Apr 2022 13:11:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650287504; bh=o3Y4MUM+DNhjUjNVPBgOfK2l3qJrVw3f+XAyqWVhVyE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xe7zgu+iF9L6XClbPNW2piycnCtfOeDJYnUy38Ddg8tdaHddW0merwUaKYiZSPqgi q9fkM7G4OWAopisTXPE7e6HIpnCP8C7V35QJXgx4WkSebEIZ6xJAcCdqWaEhnmIIN8 mZ9JDxB4yN0ZU87FBMFe8kAQ0dfNkD/fRAR+hylg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, NeilBrown , Trond Myklebust , Sasha Levin Subject: [PATCH 4.9 183/218] SUNRPC/call_alloc: async tasks mustnt block waiting for memory Date: Mon, 18 Apr 2022 14:14:09 +0200 Message-Id: <20220418121206.237161544@linuxfoundation.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220418121158.636999985@linuxfoundation.org> References: <20220418121158.636999985@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: NeilBrown [ Upstream commit c487216bec83b0c5a8803e5c61433d33ad7b104d ] When memory is short, new worker threads cannot be created and we depend on the minimum one rpciod thread to be able to handle everything. So it must not block waiting for memory. mempools are particularly a problem as memory can only be released back to the mempool by an async rpc task running. If all available workqueue threads are waiting on the mempool, no thread is available to return anything. rpc_malloc() can block, and this might cause deadlocks. So check RPC_IS_ASYNC(), rather than RPC_IS_SWAPPER() to determine if blocking is acceptable. Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin --- net/sunrpc/sched.c | 4 +++- net/sunrpc/xprtrdma/transport.c | 4 +++- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index 00d95fefdc6f..ccb9fa5812d8 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -883,8 +883,10 @@ int rpc_malloc(struct rpc_task *task) struct rpc_buffer *buf; gfp_t gfp = GFP_NOIO | __GFP_NOWARN; + if (RPC_IS_ASYNC(task)) + gfp = GFP_NOWAIT | __GFP_NOWARN; if (RPC_IS_SWAPPER(task)) - gfp = __GFP_MEMALLOC | GFP_NOWAIT | __GFP_NOWARN; + gfp |= __GFP_MEMALLOC; size += sizeof(struct rpc_buffer); if (size <= RPC_BUFFER_MAXSIZE) diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c index 3ea3bb64b6d5..f308f286e9aa 100644 --- a/net/sunrpc/xprtrdma/transport.c +++ b/net/sunrpc/xprtrdma/transport.c @@ -577,8 +577,10 @@ xprt_rdma_allocate(struct rpc_task *task) return -ENOMEM; flags = RPCRDMA_DEF_GFP; + if (RPC_IS_ASYNC(task)) + flags = GFP_NOWAIT | __GFP_NOWARN; if (RPC_IS_SWAPPER(task)) - flags = __GFP_MEMALLOC | GFP_NOWAIT | __GFP_NOWARN; + flags |= __GFP_MEMALLOC; if (!rpcrdma_get_rdmabuf(r_xprt, req, flags)) goto out_fail; -- 2.35.1