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 56848C433F5 for ; Mon, 18 Apr 2022 13:58:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245083AbiDROBU (ORCPT ); Mon, 18 Apr 2022 10:01:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57376 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242302AbiDRNjO (ORCPT ); Mon, 18 Apr 2022 09:39:14 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 062892E6AB; Mon, 18 Apr 2022 05:58:59 -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 ams.source.kernel.org (Postfix) with ESMTPS id CD674B80EC3; Mon, 18 Apr 2022 12:58:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 27BD3C385A7; Mon, 18 Apr 2022 12:58:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650286734; bh=wtfqNst6K4hfexhqxmxSOroEH8SOUtlwIWYGv2Z1h3M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O7CcXwUBXkmE3ejF1tyDWEZ5KoLWqFdLlWD431medZEl4ktrlIFG1NtWNiHyq5U/d +YVfarrqNA+bkFWN+J3I9YXrEZuK2SbHZKpfcxvrxyxsnq5YUdcRHl6JpoVFyloE5z d4oIHbzXslWtiqXqvn/R2WeJGJZTmCiVq9Dk5AgI= 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 4.14 229/284] SUNRPC/call_alloc: async tasks mustnt block waiting for memory Date: Mon, 18 Apr 2022 14:13:30 +0200 Message-Id: <20220418121218.227245899@linuxfoundation.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220418121210.689577360@linuxfoundation.org> References: <20220418121210.689577360@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: linux-kernel@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 253132130c42..4e0ebb4780df 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 ead20e6754ab..90c99919ea30 100644 --- a/net/sunrpc/xprtrdma/transport.c +++ b/net/sunrpc/xprtrdma/transport.c @@ -645,8 +645,10 @@ 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