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 X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE70AC11F6C for ; Mon, 12 Jul 2021 08:15:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B551861440 for ; Mon, 12 Jul 2021 08:15:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356986AbhGLIQz (ORCPT ); Mon, 12 Jul 2021 04:16:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:51592 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241622AbhGLHc4 (ORCPT ); Mon, 12 Jul 2021 03:32:56 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id DA0F861132; Mon, 12 Jul 2021 07:29:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626074998; bh=tWmbKHy71o7Kx6rKGktj+eUE7fNRCejxrtQ2YTbOhOY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=B9b7tFX/3azL6EhPA6m8bRJzwHJm6iLjOWQfSokN7BoPWnJTQ1WY1n+7+i8ftRqaK mP7S4KodV9y7T9LNxYosMqGPa7Ne8a4JJfTHdOaGd0nBkMxxg+ILOQOHuG6RB67ofk LL6YP6IwlTmzMTquJ1lItldYIacxXag26+nrl1LE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hulk Robot , Zhang Xiaoxu , Trond Myklebust Subject: [PATCH 5.13 068/800] SUNRPC: Should wake up the privileged task firstly. Date: Mon, 12 Jul 2021 08:01:31 +0200 Message-Id: <20210712060922.803540307@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060912.995381202@linuxfoundation.org> References: <20210712060912.995381202@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: Zhang Xiaoxu commit 5483b904bf336948826594610af4c9bbb0d9e3aa upstream. When find a task from wait queue to wake up, a non-privileged task may be found out, rather than the privileged. This maybe lead a deadlock same as commit dfe1fe75e00e ("NFSv4: Fix deadlock between nfs4_evict_inode() and nfs4_opendata_get_inode()"): Privileged delegreturn task is queued to privileged list because all the slots are assigned. If there has no enough slot to wake up the non-privileged batch tasks(session less than 8 slot), then the privileged delegreturn task maybe lost waked up because the found out task can't get slot since the session is on draining. So we should treate the privileged task as the emergency task, and execute it as for as we can. Reported-by: Hulk Robot Fixes: 5fcdfacc01f3 ("NFSv4: Return delegations synchronously in evict_inode") Cc: stable@vger.kernel.org Signed-off-by: Zhang Xiaoxu Signed-off-by: Trond Myklebust Signed-off-by: Greg Kroah-Hartman --- net/sunrpc/sched.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -592,6 +592,15 @@ static struct rpc_task *__rpc_find_next_ struct rpc_task *task; /* + * Service the privileged queue. + */ + q = &queue->tasks[RPC_NR_PRIORITY - 1]; + if (queue->maxpriority > RPC_PRIORITY_PRIVILEGED && !list_empty(q)) { + task = list_first_entry(q, struct rpc_task, u.tk_wait.list); + goto out; + } + + /* * Service a batch of tasks from a single owner. */ q = &queue->tasks[queue->priority];