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 13F72C433EF for ; Tue, 12 Apr 2022 06:48:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350788AbiDLGug (ORCPT ); Tue, 12 Apr 2022 02:50:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37760 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350637AbiDLGmk (ORCPT ); Tue, 12 Apr 2022 02:42:40 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8CFA337A84; Mon, 11 Apr 2022 23:36:34 -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 CBC0C618FF; Tue, 12 Apr 2022 06:36:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DA017C385A1; Tue, 12 Apr 2022 06:36:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649745393; bh=eXCTnhBMDSi9LGLaJX4Otpaaqm7MtAtgKEfyeEd7b9M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ev+fynPqvlvPGuErqaX12CXmM8ODR2RPeFZs7b10m+5dPNcvfdaKdN+qm5YJjPid4 DJgX++SLBeZ1pw1Jhkfani28KotIxZCPZE/MXUBlRoSLiAndbbYOv6YQDrIILJEkPf OKsb1LCkwgY/eLIbZxGlqxjMGQD1lIu21zM7n0VY= 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 5.10 082/171] SUNRPC/call_alloc: async tasks mustnt block waiting for memory Date: Tue, 12 Apr 2022 08:29:33 +0200 Message-Id: <20220412062930.259731583@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220412062927.870347203@linuxfoundation.org> References: <20220412062927.870347203@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 c045f63d11fa..6e4d476c6324 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -1012,8 +1012,10 @@ int rpc_malloc(struct rpc_task *task) struct rpc_buffer *buf; gfp_t gfp = GFP_NOFS; + 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 8e2368a0c2a2..fb7a0ab27899 100644 --- a/net/sunrpc/xprtrdma/transport.c +++ b/net/sunrpc/xprtrdma/transport.c @@ -572,8 +572,10 @@ xprt_rdma_allocate(struct rpc_task *task) gfp_t flags; 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_check_regbuf(r_xprt, req->rl_sendbuf, rqst->rq_callsize, flags)) -- 2.35.1