Received: by 2002:a05:6a10:f3d0:0:0:0:0 with SMTP id a16csp178813pxv; Wed, 14 Jul 2021 01:11:52 -0700 (PDT) X-Google-Smtp-Source: ABdhPJx4Lqn6t3uqP/pYTtHHtX0YAYD7+Cj3gV573r4vWbcgLEJmMEhwO8Brp4uLFxa+xhBxQkvi X-Received: by 2002:a02:7348:: with SMTP id a8mr7728026jae.116.1626250312013; Wed, 14 Jul 2021 01:11:52 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1626250312; cv=none; d=google.com; s=arc-20160816; b=Y/RsdwpPjKijHxOKhg8PFMKkD6RWtTOJqmxCmykUjCR5lyEPyw5i1bkAQ34OAYiNiR uKJCeXf4N5hM421CxoGpQgCC1JSt3e876BL3+a7Uvz/GyMOLOttz4CSq1NKU0/yM5eT3 A/9Xah+xu1TaI3c7167UTntfiiD9oOiPn+O71VkbnOF49JVuttrPF5u5YEyU94XeQj1R eorIZJ5spdx7sT6CzF7/qa/PoJa3DsVb7gw9n8o+i3P7XBWLfOHGAyJ9TSRcQRqHULvr /SWgP61fR26JkUFd2oeD2Z8qedpaeFePbz6QeAaZRft70y2Kd6Y75vHyY33JGn0Lx5T2 ZHzA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:content-language :in-reply-to:mime-version:user-agent:date:message-id:from:references :cc:to:subject:dkim-signature; bh=J8UM8qKhd8lVsw4YNA+FXQlest2HKWswEUdYrUZ85lM=; b=z30hqjxw6xKRCBMPlXX3SWdy/UOcuwXPd3f5moosElOqdKsv74IZWt5YKRt3RDBYXP xHd1QHgBdu9lVPIDzbhVN4jQo//pLbXXklnRssKI3jW2vS5o4avkLvGByZpTuE8Vky3L bph9W4moLx7SjUiJbANfbV6WKhFhLfhApdb1wMFKI+xWICo5UPbl1AtJBOQJ2tnqjnS7 ma0BRcYoiViLJZOw/bvHjjqaRl6GYzlI0HBPKkd4MtKhVvUhd9iAT3YGuoMVksDjJOrA p31kivmfWtk4c6McBRN4KdLbWOsY30B14FDUy9gkccNZXPmVsqie07FEiBzcktLRzMqC M7bw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=YqvZWYKB; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id x6si1942002ilv.67.2021.07.14.01.11.39; Wed, 14 Jul 2021 01:11:52 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=YqvZWYKB; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238421AbhGNINE (ORCPT + 99 others); Wed, 14 Jul 2021 04:13:04 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:38130 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238378AbhGNINE (ORCPT ); Wed, 14 Jul 2021 04:13:04 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1626250212; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=J8UM8qKhd8lVsw4YNA+FXQlest2HKWswEUdYrUZ85lM=; b=YqvZWYKBI2YUJde5gj1bqKggNwNh5QRvd0bu9Hn3mklgfr/iOI1fHdEIFSi7UZpiYAa6Kw sszwEGjGcuPAwvQlxcuklpoa/o8GP1sbOJHi2678EsgvSmvHgLNvmMhsZ4aQANwPZXpsb3 +CsMGgbh228g4pI+hf7u/PoJ+wdrOt8= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-125-OXFoNnDtMbqL0ZNXiXwhIg-1; Wed, 14 Jul 2021 04:10:11 -0400 X-MC-Unique: OXFoNnDtMbqL0ZNXiXwhIg-1 Received: by mail-wm1-f70.google.com with SMTP id l3-20020a1c79030000b029021ecdaeeafaso204451wme.7 for ; Wed, 14 Jul 2021 01:10:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=J8UM8qKhd8lVsw4YNA+FXQlest2HKWswEUdYrUZ85lM=; b=VRTJ/nnSYxVWOovGyx2VbSR52tZKco/Ut/yBc4ibS7+CAOjXEts3BC5+n3GkeuvmX8 enzppQC+VAtIFtX+dWMOy3KInMClRPI7oa5/Pr5/cEO+OGztsrar+nEPAKwlLHrcK6f7 6tpXzR8k7B/gxb4CG/C9tqF48jdOgTxfpLsdIUshpGx/Z3M/OHdxvRKLeFQpN/yhjCE4 yrOOOnLNNTxBZMTMbi3QlchzxGD+4G0rYanePo6NqpP5RSX7BrXVpM2KrHxAb2g1JkEt 5xmO4QS8BA9kdOzzBti5dwZ90vIFNzZwtIyeilKvbf5071pF5LmD9XrKWMX+ORHRMryE koog== X-Gm-Message-State: AOAM5318A7rYrT6ttBW9yJd6RxtnNClnIN0knUfJ3gUUtQTgl2Z1QMDZ Dqgfn/9eYkVSLZHXGzukeEvScUE1XasPy4VNVSxcdSjQjewhIy+/FZDTKfPFT/qQmX6XoLPwkFs TIREI0sH94Butd2hV1EyulLHB X-Received: by 2002:a5d:457b:: with SMTP id a27mr11044874wrc.280.1626250210355; Wed, 14 Jul 2021 01:10:10 -0700 (PDT) X-Received: by 2002:a5d:457b:: with SMTP id a27mr11044847wrc.280.1626250210094; Wed, 14 Jul 2021 01:10:10 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:c8dd:75d4:99ab:290a? ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id c15sm1292998wmr.28.2021.07.14.01.10.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 14 Jul 2021 01:10:09 -0700 (PDT) Subject: Re: 5.13-rt1 + KVM = WARNING: at fs/eventfd.c:74 eventfd_signal() To: Daniel Bristot de Oliveira , Thomas Gleixner , Sebastian Andrzej Siewior , "Jason Wang (jasowang@redhat.com)" , "Michael S. Tsirkin" Cc: LKML , Al Viro References: From: Paolo Bonzini Message-ID: <8dfc0ee9-b97a-8ca8-d057-31c8cad3f5b6@redhat.com> Date: Wed, 14 Jul 2021 10:10:08 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14/07/21 10:01, Daniel Bristot de Oliveira wrote: > Hey > > I use kvm-vm for regular development, and while using the kernel-rt v5.13-rt1 > (the latest) on the host, and a regular kernel on the guest, after a while, > this happens: > > [ 1723.404979] ------------[ cut here ]------------ > [ 1723.404981] WARNING: CPU: 12 PID: 2554 at fs/eventfd.c:74 eventfd_signal+0x7e/0x90 > [ 1723.405055] RIP: 0010:eventfd_signal+0x7e/0x90 > [ 1723.405059] Code: 01 00 00 00 be 03 00 00 00 4c 89 ef e8 5b ec d9 ff 65 ff 0d e4 34 c9 5a 4c 89 ef e8 ec a8 86 00 4c 89 e0 5b 5d 41 5c 41 5d c3 <0f> 0b 45 31 e4 5b 5d 4c 89 e0 41 5c 41 5d c3 0f 1f 00 0f 1f 44 00 > [ 1723.405078] vhost_tx_batch.constprop.0+0x7d/0xc0 [vhost_net] > [ 1723.405083] handle_tx_copy+0x15b/0x5c0 [vhost_net] > [ 1723.405088] ? __vhost_add_used_n+0x200/0x200 [vhost] > [ 1723.405092] handle_tx+0xa5/0xe0 [vhost_net] > [ 1723.405095] vhost_worker+0x93/0xd0 [vhost] > [ 1723.405099] kthread+0x186/0x1a0 > [ 1723.405103] ? __kthread_parkme+0xa0/0xa0 > [ 1723.405105] ret_from_fork+0x22/0x30 > [ 1723.405110] ---[ end trace 0000000000000002 ]--- The WARN has this comment above: /* * Deadlock or stack overflow issues can happen if we recurse here * through waitqueue wakeup handlers. If the caller users potentially * nested waitqueues with custom wakeup handlers, then it should * check eventfd_signal_count() before calling this function. If * it returns true, the eventfd_signal() call should be deferred to a * safe context. */ This was added in 2020, so it's unlikely to be the direct cause of the change. What is a known-good version for the host? Since it is not KVM stuff, I'm CCing Michael and Jason. Paolo