From patchwork Sat Jun 26 07:50:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhang Xiaoxu X-Patchwork-Id: 12346275 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 9A2BEC49EA6 for ; Sat, 26 Jun 2021 07:44:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 82A1F6191B for ; Sat, 26 Jun 2021 07:44:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229952AbhFZHrI (ORCPT ); Sat, 26 Jun 2021 03:47:08 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:5085 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229573AbhFZHrF (ORCPT ); Sat, 26 Jun 2021 03:47:05 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.53]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4GBm3M1KVYzXlMQ; Sat, 26 Jun 2021 15:39:27 +0800 (CST) Received: from dggpeml500023.china.huawei.com (7.185.36.114) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Sat, 26 Jun 2021 15:44:41 +0800 Received: from localhost.localdomain (10.175.101.6) by dggpeml500023.china.huawei.com (7.185.36.114) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Sat, 26 Jun 2021 15:44:41 +0800 From: Zhang Xiaoxu To: , , , , , Subject: [PATCH 1/2] SUNRPC: Fix the batch tasks count wraparound. Date: Sat, 26 Jun 2021 15:50:41 +0800 Message-ID: <20210626075042.805548-2-zhangxiaoxu5@huawei.com> X-Mailer: git-send-email 2.25.4 In-Reply-To: <20210626075042.805548-1-zhangxiaoxu5@huawei.com> References: <20210626075042.805548-1-zhangxiaoxu5@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.101.6] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpeml500023.china.huawei.com (7.185.36.114) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org The 'queue->nr' will wraparound from 0 to 255 when only current priority queue has tasks. 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. When non-privileged task complete and release the slot, a non-privileged maybe picked out. It maybe allocate slot failed when the session on draining. If the 'queue->nr' has wraparound to 255, and no enough slot to service it, then the privileged delegreturn will lost to wake up. So we should avoid the wraparound on 'queue->nr'. Reported-by: Hulk Robot Fixes: 5fcdfacc01f3 ("NFSv4: Return delegations synchronously in evict_inode") Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Zhang Xiaoxu --- net/sunrpc/sched.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index 39ed0e0afe6d..37cd09574628 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -595,7 +595,8 @@ static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *q * Service a batch of tasks from a single owner. */ q = &queue->tasks[queue->priority]; - if (!list_empty(q) && --queue->nr) { + if (!list_empty(q) && queue->nr) { + queue->nr -= 1; task = list_first_entry(q, struct rpc_task, u.tk_wait.list); goto out; } From patchwork Sat Jun 26 07:50:42 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhang Xiaoxu X-Patchwork-Id: 12346277 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 8401CC49EA5 for ; Sat, 26 Jun 2021 07:44:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 688A36186A for ; Sat, 26 Jun 2021 07:44:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229573AbhFZHrI (ORCPT ); Sat, 26 Jun 2021 03:47:08 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:5438 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229948AbhFZHrF (ORCPT ); Sat, 26 Jun 2021 03:47:05 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.56]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4GBm5b5ws8z71Rl; Sat, 26 Jun 2021 15:41:23 +0800 (CST) Received: from dggpeml500023.china.huawei.com (7.185.36.114) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Sat, 26 Jun 2021 15:44:41 +0800 Received: from localhost.localdomain (10.175.101.6) by dggpeml500023.china.huawei.com (7.185.36.114) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Sat, 26 Jun 2021 15:44:41 +0800 From: Zhang Xiaoxu To: , , , , , Subject: [PATCH 2/2] SUNRPC: Should wake up the privileged task firstly. Date: Sat, 26 Jun 2021 15:50:42 +0800 Message-ID: <20210626075042.805548-3-zhangxiaoxu5@huawei.com> X-Mailer: git-send-email 2.25.4 In-Reply-To: <20210626075042.805548-1-zhangxiaoxu5@huawei.com> References: <20210626075042.805548-1-zhangxiaoxu5@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.101.6] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggpeml500023.china.huawei.com (7.185.36.114) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org 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 --- net/sunrpc/sched.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index 37cd09574628..e08ce3b791fd 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -591,6 +591,15 @@ static struct rpc_task *__rpc_find_next_queued_priority(struct rpc_wait_queue *q struct list_head *q; 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. */