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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 EFC6DC433E6 for ; Mon, 28 Dec 2020 15:39:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BEDF122472 for ; Mon, 28 Dec 2020 15:39:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2632900AbgL1PjC (ORCPT ); Mon, 28 Dec 2020 10:39:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:51310 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406201AbgL1Ntp (ORCPT ); Mon, 28 Dec 2020 08:49:45 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id CF6B9208BA; Mon, 28 Dec 2020 13:49:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1609163344; bh=x3l4fW3BSwnZ31oyFfPlfxoebzrzZsMzNpf79VmZLqA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=09wT2tqCW4yd5ab5BJPuu+uTWvXWQY0kj2HLVRr/bZKmb0Vpk9kmv5Lh4jDOZgS3u v9zSKLcOaFB2mk8LNmnyvas6YOLbAZOiThM4YmQmxLdiGGmvUOBLPetJ5w32myOaY/ uHFtm8Rv0FMUpONciLXp9q9nXZvXasQH6fE1phWo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?=C2=A0Cheng=C2=A0Lin=C2=A0?= , =?UTF-8?q?=C2=A0Yi=C2=A0Wang=C2=A0?= , Chuck Lever , Sasha Levin Subject: [PATCH 5.4 254/453] nfs_common: need lock during iterate through the list Date: Mon, 28 Dec 2020 13:48:10 +0100 Message-Id: <20201228124949.449796028@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201228124937.240114599@linuxfoundation.org> References: <20201228124937.240114599@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: Cheng Lin [ Upstream commit 4a9d81caf841cd2c0ae36abec9c2963bf21d0284 ] If the elem is deleted during be iterated on it, the iteration process will fall into an endless loop. kernel: NMI watchdog: BUG: soft lockup - CPU#4 stuck for 22s! [nfsd:17137] PID: 17137  TASK: ffff8818d93c0000  CPU: 4   COMMAND: "nfsd"     [exception RIP: __state_in_grace+76]     RIP: ffffffffc00e817c  RSP: ffff8818d3aefc98  RFLAGS: 00000246     RAX: ffff881dc0c38298  RBX: ffffffff81b03580  RCX: ffff881dc02c9f50     RDX: ffff881e3fce8500  RSI: 0000000000000001  RDI: ffffffff81b03580     RBP: ffff8818d3aefca0   R8: 0000000000000020   R9: ffff8818d3aefd40     R10: ffff88017fc03800  R11: ffff8818e83933c0  R12: ffff8818d3aefd40     R13: 0000000000000000  R14: ffff8818e8391068  R15: ffff8818fa6e4000     CS: 0010  SS: 0018  #0 [ffff8818d3aefc98] opens_in_grace at ffffffffc00e81e3 [grace]  #1 [ffff8818d3aefca8] nfs4_preprocess_stateid_op at ffffffffc02a3e6c [nfsd]  #2 [ffff8818d3aefd18] nfsd4_write at ffffffffc028ed5b [nfsd]  #3 [ffff8818d3aefd80] nfsd4_proc_compound at ffffffffc0290a0d [nfsd]  #4 [ffff8818d3aefdd0] nfsd_dispatch at ffffffffc027b800 [nfsd]  #5 [ffff8818d3aefe08] svc_process_common at ffffffffc02017f3 [sunrpc]  #6 [ffff8818d3aefe70] svc_process at ffffffffc0201ce3 [sunrpc]  #7 [ffff8818d3aefe98] nfsd at ffffffffc027b117 [nfsd]  #8 [ffff8818d3aefec8] kthread at ffffffff810b88c1  #9 [ffff8818d3aeff50] ret_from_fork at ffffffff816d1607 The troublemake elem: crash> lock_manager ffff881dc0c38298 struct lock_manager {   list = {     next = 0xffff881dc0c38298,     prev = 0xffff881dc0c38298   },   block_opens = false } Fixes: c87fb4a378f9 ("lockd: NLM grace period shouldn't block NFSv4 opens") Signed-off-by: Cheng Lin  Signed-off-by: Yi Wang  Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/nfs_common/grace.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/fs/nfs_common/grace.c b/fs/nfs_common/grace.c index b73d9dd37f73c..26f2a50eceac9 100644 --- a/fs/nfs_common/grace.c +++ b/fs/nfs_common/grace.c @@ -69,10 +69,14 @@ __state_in_grace(struct net *net, bool open) if (!open) return !list_empty(grace_list); + spin_lock(&grace_lock); list_for_each_entry(lm, grace_list, list) { - if (lm->block_opens) + if (lm->block_opens) { + spin_unlock(&grace_lock); return true; + } } + spin_unlock(&grace_lock); return false; } -- 2.27.0