From patchwork Tue Apr 12 06:29:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 560761 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 454E8C433EF for ; Tue, 12 Apr 2022 06:43:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350274AbiDLGpi (ORCPT ); Tue, 12 Apr 2022 02:45:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38916 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350683AbiDLGm6 (ORCPT ); Tue, 12 Apr 2022 02:42:58 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E829617E36; Mon, 11 Apr 2022 23:36:38 -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 68446B81B49; Tue, 12 Apr 2022 06:36:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AE089C385A6; Tue, 12 Apr 2022 06:36:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649745396; bh=ybLqq2JlpuKJF04INgQ7dIq+Q8rNuZfr5+6uW8wlq4g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ihxuRtlzzty2LMA5XAgKbgWzzVhsw+MvTlgM6X+z4nGXbz73JaCLzAr+23p2ilRRp GdrUnVwYAZiCLwsshsEhPEMrLwt8FT7pBIZWrWto7o9lqa0PR4NrVi2GymF0GaGF+Z HaiiG3GletRZDbSnOrnOXxd4iUT4vfuPGwMOR02g= 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 5.10 083/171] SUNRPC/xprt: async tasks mustnt block waiting for memory Date: Tue, 12 Apr 2022 08:29:34 +0200 Message-Id: <20220412062930.289655419@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 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: NeilBrown [ Upstream commit a721035477fb5fb8abc738fbe410b07c12af3dc5 ] 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. xprt_dynamic_alloc_slot can block indefinitely. This can tie up all workqueue threads and NFS can deadlock. So when called from a workqueue, set __GFP_NORETRY. The rdma alloc_slot already does not block. However it sets the error to -EAGAIN suggesting this will trigger a sleep. It does not. As we can see in call_reserveresult(), only -ENOMEM causes a sleep. -EAGAIN causes immediate retry. Signed-off-by: NeilBrown Signed-off-by: Trond Myklebust Signed-off-by: Sasha Levin --- net/sunrpc/xprt.c | 5 ++++- net/sunrpc/xprtrdma/transport.c | 2 +- 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index 46304e647c49..441a8604c060 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -1635,12 +1635,15 @@ static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt) { struct rpc_rqst *req = ERR_PTR(-EAGAIN); + gfp_t gfp_mask = GFP_KERNEL; if (xprt->num_reqs >= xprt->max_reqs) goto out; ++xprt->num_reqs; spin_unlock(&xprt->reserve_lock); - req = kzalloc(sizeof(struct rpc_rqst), GFP_NOFS); + if (current->flags & PF_WQ_WORKER) + gfp_mask |= __GFP_NORETRY | __GFP_NOWARN; + req = kzalloc(sizeof(*req), gfp_mask); spin_lock(&xprt->reserve_lock); if (req != NULL) goto out; diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c index fb7a0ab27899..9cf10cfb85c6 100644 --- a/net/sunrpc/xprtrdma/transport.c +++ b/net/sunrpc/xprtrdma/transport.c @@ -519,7 +519,7 @@ xprt_rdma_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task) return; out_sleep: - task->tk_status = -EAGAIN; + task->tk_status = -ENOMEM; xprt_add_backlog(xprt, task); }