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=-5.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_MUTT 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 1D224C04AAD for ; Wed, 8 May 2019 09:19:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E0D5620656 for ; Wed, 8 May 2019 09:19:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kroah.com header.i=@kroah.com header.b="Jf905llr"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="Z2Fg2iDE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726685AbfEHJT3 (ORCPT ); Wed, 8 May 2019 05:19:29 -0400 Received: from wout1-smtp.messagingengine.com ([64.147.123.24]:43633 "EHLO wout1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726589AbfEHJT2 (ORCPT ); Wed, 8 May 2019 05:19:28 -0400 Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailout.west.internal (Postfix) with ESMTP id 63B634A3; Wed, 8 May 2019 05:19:25 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute6.internal (MEProxy); Wed, 08 May 2019 05:19:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kroah.com; h= date:from:to:cc:subject:message-id:references:mime-version :content-type:in-reply-to; s=fm3; bh=Qx5s+3gMk23EZhvj8bdaljTEiFo MwLGd3Y7gAN+zmYA=; b=Jf905llrUndvCGe7u6vbkIzRIWRHn9DVBqaGx6I+zwI mq6OCGsQg9PFDDC5NJI1Bv/QjFHDQ6Ah0hUMNAKVram3DcbVVybABxkHxLAYS4VY vP+7nzyHuUiZojYC5pwNNLVPEM/nmpky7D+SW0DdPO3seIhE9Fv0NQfTUSxiZYX4 7uerxXz1fz8wHf3HG+n2ro50s0PPFOczYBzrLSM206xnOrEAgwES0LPspiE72j92 3Marm/mXznypKW3I3wd5QiPooW54Ei38RJmdymZR0OTbEhCRBqqzVasLPnL3//3y 23GtgdaO8qMEsO0/QOzsexlGNr+x/IFEYk9nAd4vSog== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=Qx5s+3 gMk23EZhvj8bdaljTEiFoMwLGd3Y7gAN+zmYA=; b=Z2Fg2iDEYzwRFzX/PBxUeN Z4o8I0CUEuqz11R0tgEPQUpWx3GpqLO2bhAd0fL6ISqakYxbk6JZNvuaVNnSJbU4 s6OCyCgS65QciXAe6a5eKYjUGiDmy+4TrzT3kLsst2jvq4fVm8SU5hVJ7dR+wnhF P0mnhilzFxtRZ7AiwoWvPb9EhNUTptudWRj4wLJsK2XMbJ/HhJonlvTZ5T4W4O1C YGSBHtHGlzL7NDVPD33ZUmB4dNrvcA30RGeKEXgiYDlB/Cr8f7bKeL9DHgdrJdPI ZrwX7QUg/mG9LL1rNkBxcZNlP8PnEQLnoHMnfE7weJQ8xqaz0bbRvUm9qJJDAayA == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduuddrkeefgdduvdcutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenuc fjughrpeffhffvuffkfhggtggujggfsehttdertddtredvnecuhfhrohhmpefirhgvghcu mffjuceoghhrvghgsehkrhhorghhrdgtohhmqeenucffohhmrghinhepkhgvrhhnvghlrd horhhgnecukfhppeekgedrvdeguddrudeliedrleeinecurfgrrhgrmhepmhgrihhlfhhr ohhmpehgrhgvgheskhhrohgrhhdrtghomhenucevlhhushhtvghrufhiiigvpedt X-ME-Proxy: Received: from localhost (unknown [84.241.196.96]) by mail.messagingengine.com (Postfix) with ESMTPA id 83B641037C; Wed, 8 May 2019 05:19:23 -0400 (EDT) Date: Wed, 8 May 2019 11:19:21 +0200 From: Greg KH To: Yihao Wu Cc: linux-nfs@vger.kernel.org, Jeff Layton , "J. Bruce Fields" , stable@vger.kernel.org, Joseph Qi , caspar@linux.alibaba.com Subject: Re: [PATCH 1/2] NFSv4.1: Again fix a race where CB_NOTIFY_LOCK fails to wake a waiter Message-ID: <20190508091921.GA1968@kroah.com> References: <2a1cebca-1efb-1686-475b-a581e50e61b4@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2a1cebca-1efb-1686-475b-a581e50e61b4@linux.alibaba.com> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-nfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org On Wed, May 08, 2019 at 05:13:25PM +0800, Yihao Wu wrote: > Commit b7dbcc0e433f ""NFSv4.1: Fix a race where CB_NOTIFY_LOCK fails > to wake a waiter" found this bug. However it didn't fix it. This can > be fixed by adding memory barrier pair. > > Specifically, if any CB_NOTIFY_LOCK should be handled between unlocking > the wait queue and freezable_schedule_timeout, only two cases are > possible. So CB_NOTIFY_LOCK will not be dropped unexpectly. > > 1. The callback thread marks the NFS client as waked. Then NFS client > noticed that itself is waked, so it don't goes to sleep. And it cleans > its wake mark. > > 2. The NFS client noticed that itself is not waked yet, so it goes to > sleep. No modification will ever happen to the wake mark in between. > > Fixes: a1d617d ("nfs: allow blocking locks to be awoken by lock callbacks") > Signed-off-by: Yihao Wu > --- > fs/nfs/nfs4proc.c | 21 +++++---------------- > 1 file changed, 5 insertions(+), 16 deletions(-) This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.