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=-14.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,T_DKIMWL_WL_MED,USER_IN_DEF_DKIM_WL 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 E3A95C04AAB for ; Mon, 6 May 2019 20:20:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB8252087F for ; Mon, 6 May 2019 20:20:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="cmUNiJ98" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726544AbfEFUUL (ORCPT ); Mon, 6 May 2019 16:20:11 -0400 Received: from mail-wm1-f67.google.com ([209.85.128.67]:51555 "EHLO mail-wm1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726346AbfEFUUK (ORCPT ); Mon, 6 May 2019 16:20:10 -0400 Received: by mail-wm1-f67.google.com with SMTP id o189so6461654wmb.1 for ; Mon, 06 May 2019 13:20:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=5KVj2cIFo4sf42IOvLasjrLGxhKPAN71ZeOyGOXbgEg=; b=cmUNiJ98WYG7sItDJoJr3sz3tx87o4/cseKFyRTB6KPblTqcD6p2X4Cl9Dt7uhRrbX hwg3vsZ07HYU/TiXZVulJMltTrF/i8J+DlWJ8kYkqKoW3peDCioHiWUYbjftKe6qPglk +yDK+zpMcVMUEQBzOIhOI3WfpIT6a5+4NO1/0EUR7vAT5tyU2DdWvP3oWcTcWKXeX+YG C6Q7Hq5oLAY6JvccnQw8frAjd7/cZts981BUwUlJrmEuKmxiAeJ9UADewVtE7o06DJu9 8etmdNoNdE/3u5DC1DPp9fes9/FTjtks4PT0YKvOg69TSeWpiw1vKegIHhwPwDgriAPk EYsw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=5KVj2cIFo4sf42IOvLasjrLGxhKPAN71ZeOyGOXbgEg=; b=bURqFuzKnwqYxkAES3gajhry6AvFbCGB5FPhrbjcIMFf22qz3a7uSY4Y+kJo2Fh5qP 3inAAfj89DU5Jb0mVh17XcUvZZZ5CvOHaJ4e5tJTTU5jm7//F4GTETRobAy7qlSlLjpo gKQcacyj9Ltg2LXpuwGmZZrqODHkeKlaPfx7PTuZZAmXAG9F4JBUDlfjzubcN1+JTwyZ MEeHfD8zY4iTgZNBDVjyePHBlEJ1+ug1PaM+DBfr06Apg4K4RSfLhoGEaI+3RSeDucEu 3KvhGtRxD5cw0BG93qFM2fYpXvNlwqIi0aGSKR//fQkuBRRR7FiEUq9BVFbAvhU+ejXK Dx3w== X-Gm-Message-State: APjAAAVDW61RMIfuXT801EvAhLDJIQDk/BR0BH7ebLBMGSS/smJg6dIT 7KA99vr1ikev2Cw1MXLYRfY6PqUdpz82i/6haqeQvQ== X-Google-Smtp-Source: APXvYqw6YN+mxes4KsRlBEwg0TxslCYp4jV8sOumNLnEbdftzDK/6jIQfDvI0cZj8kywJzf8b7wnJVv8SPDDt1cLFo8= X-Received: by 2002:a05:600c:2248:: with SMTP id a8mr18696267wmm.75.1557174006447; Mon, 06 May 2019 13:20:06 -0700 (PDT) MIME-Version: 1.0 References: <20190501003001.186239-1-jemoreira@google.com> <20190501190831.GF22391@stefanha-x1.localdomain> <20190502082045.u3xypjbac5npbhtc@steredhat.homenet.telecomitalia.it> In-Reply-To: <20190502082045.u3xypjbac5npbhtc@steredhat.homenet.telecomitalia.it> From: Jorge Moreira Broche Date: Mon, 6 May 2019 13:19:55 -0700 Message-ID: Subject: Re: [PATCH] vsock/virtio: Initialize core virtio vsock before registering the driver To: Stefano Garzarella Cc: Stefan Hajnoczi , linux-kernel@vger.kernel.org, "David S. Miller" , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, kernel-team@android.com, stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Wed, May 01, 2019 at 03:08:31PM -0400, Stefan Hajnoczi wrote: > > On Tue, Apr 30, 2019 at 05:30:01PM -0700, Jorge E. Moreira wrote: > > > Avoid a race in which static variables in net/vmw_vsock/af_vsock.c are > > > accessed (while handling interrupts) before they are initialized. > > > > > > > > > [ 4.201410] BUG: unable to handle kernel paging request at ffffffffffffffe8 > > > [ 4.207829] IP: vsock_addr_equals_addr+0x3/0x20 > > > [ 4.211379] PGD 28210067 P4D 28210067 PUD 28212067 PMD 0 > > > [ 4.211379] Oops: 0000 [#1] PREEMPT SMP PTI > > > [ 4.211379] Modules linked in: > > > [ 4.211379] CPU: 1 PID: 30 Comm: kworker/1:1 Not tainted 4.14.106-419297-gd7e28cc1f241 #1 > > > [ 4.211379] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 > > > [ 4.211379] Workqueue: virtio_vsock virtio_transport_rx_work > > > [ 4.211379] task: ffffa3273d175280 task.stack: ffffaea1800e8000 > > > [ 4.211379] RIP: 0010:vsock_addr_equals_addr+0x3/0x20 > > > [ 4.211379] RSP: 0000:ffffaea1800ebd28 EFLAGS: 00010286 > > > [ 4.211379] RAX: 0000000000000002 RBX: 0000000000000000 RCX: ffffffffb94e42f0 > > > [ 4.211379] RDX: 0000000000000400 RSI: ffffffffffffffe0 RDI: ffffaea1800ebdd0 > > > [ 4.211379] RBP: ffffaea1800ebd58 R08: 0000000000000001 R09: 0000000000000001 > > > [ 4.211379] R10: 0000000000000000 R11: ffffffffb89d5d60 R12: ffffaea1800ebdd0 > > > [ 4.211379] R13: 00000000828cbfbf R14: 0000000000000000 R15: ffffaea1800ebdc0 > > > [ 4.211379] FS: 0000000000000000(0000) GS:ffffa3273fd00000(0000) knlGS:0000000000000000 > > > [ 4.211379] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > [ 4.211379] CR2: ffffffffffffffe8 CR3: 000000002820e001 CR4: 00000000001606e0 > > > [ 4.211379] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > > [ 4.211379] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > > [ 4.211379] Call Trace: > > > [ 4.211379] ? vsock_find_connected_socket+0x6c/0xe0 > > > [ 4.211379] virtio_transport_recv_pkt+0x15f/0x740 > > > [ 4.211379] ? detach_buf+0x1b5/0x210 > > > [ 4.211379] virtio_transport_rx_work+0xb7/0x140 > > > [ 4.211379] process_one_work+0x1ef/0x480 > > > [ 4.211379] worker_thread+0x312/0x460 > > > [ 4.211379] kthread+0x132/0x140 > > > [ 4.211379] ? process_one_work+0x480/0x480 > > > [ 4.211379] ? kthread_destroy_worker+0xd0/0xd0 > > > [ 4.211379] ret_from_fork+0x35/0x40 > > > [ 4.211379] Code: c7 47 08 00 00 00 00 66 c7 07 28 00 c7 47 08 ff ff ff ff c7 47 04 ff ff ff ff c3 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 8b 47 08 <3b> 46 08 75 0a 8b 47 04 3b 46 04 0f 94 c0 c3 31 c0 c3 90 66 2e > > > [ 4.211379] RIP: vsock_addr_equals_addr+0x3/0x20 RSP: ffffaea1800ebd28 > > > [ 4.211379] CR2: ffffffffffffffe8 > > > [ 4.211379] ---[ end trace f31cc4a2e6df3689 ]--- > > > [ 4.211379] Kernel panic - not syncing: Fatal exception in interrupt > > > [ 4.211379] Kernel Offset: 0x37000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) > > > [ 4.211379] Rebooting in 5 seconds.. > > > > > > Fixes: 22b5c0b63f32 ("vsock/virtio: fix kernel panic after device hot-unplug") > > > Cc: Stefan Hajnoczi > > > Cc: "David S. Miller" > > > Cc: kvm@vger.kernel.org > > > Cc: virtualization@lists.linux-foundation.org > > > Cc: netdev@vger.kernel.org > > > Cc: kernel-team@android.com > > > Cc: stable@vger.kernel.org [4.9+] > > > Signed-off-by: Jorge E. Moreira > > > --- > > > net/vmw_vsock/virtio_transport.c | 13 ++++++------- > > > 1 file changed, 6 insertions(+), 7 deletions(-) > > > > > > diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c > > > index 15eb5d3d4750..96ab344f17bb 100644 > > > --- a/net/vmw_vsock/virtio_transport.c > > > +++ b/net/vmw_vsock/virtio_transport.c > > > @@ -702,28 +702,27 @@ static int __init virtio_vsock_init(void) > > > if (!virtio_vsock_workqueue) > > > return -ENOMEM; > > > > > > - ret = register_virtio_driver(&virtio_vsock_driver); > > > + ret = vsock_core_init(&virtio_transport.transport); > > > > Have you checked that all transport callbacks are safe even if another > > CPU calls them while virtio_vsock_probe() is executing on another CPU? > > > > I have the same doubt. > > What do you think to take the 'the_virtio_vsock_mutex' in the > virtio_vsock_init(), keeping the previous order? > > This should prevent this issue because the virtio_vsock_probe() remains > blocked in the mutex until the end of vsock_core_init(). > > Cheers, > Stefano Hi Stefan, Stefano, Sorry for the late reply. @Stefan The order of vsock_core_exit() does not need to be changed to fix the bug I found, but not changing it means the exit function is not symmetric to the init function. @Stefano Taking the mutex from virtio_vsock_init() could work too (I haven't tried it yet), but it's unnecessary, all that needs to be done is properly initialize vsock_core before attempting to use it. I would prefer to change the order in virtio_vsock_init, while leaving virtio_vsock_exit unchanged, but I'll leave the final decision to you since I am not very familiar with the inner workings of these modules.