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=-8.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 76258C07E96 for ; Thu, 15 Jul 2021 09:51:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 59ED1611AB for ; Thu, 15 Jul 2021 09:51:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240485AbhGOJyb (ORCPT ); Thu, 15 Jul 2021 05:54:31 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:20162 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232473AbhGOJyb (ORCPT ); Thu, 15 Jul 2021 05:54:31 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1626342697; 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=dR8uPancX/qqeTPCBjElsarS+8BXPFXgvmywV29J+tI=; b=BdakbEAJ8MAATnMejq7Zt0BjtVcr8Iv9C39kjg0ImXGkxIFHI7RoG65aHMVo/B8Ge88wiY WqjiYprr5v8lgNVE+4824+D/VcOEZkIpphC/DYiIdHdU2Rm82iRTTIIgfeMa7TK3DnSU5e LathBIvoWoPchxx66K84cgiq8xByToU= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-382-51R01BeJOKetsMC0hx08YA-1; Thu, 15 Jul 2021 05:51:36 -0400 X-MC-Unique: 51R01BeJOKetsMC0hx08YA-1 Received: by mail-wr1-f71.google.com with SMTP id m4-20020adffa040000b02901404c442853so3066601wrr.12 for ; Thu, 15 Jul 2021 02:51:36 -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=dR8uPancX/qqeTPCBjElsarS+8BXPFXgvmywV29J+tI=; b=emK+NooPYIcOkmDgoTr36t9ep+5Xoj/w2uE+LcP/Li3Rn1OcrCC5edWX6Bn6FmXEhk gnDth4BI2Of7dmBqXwYp57+Acy4DqWlEs6B+oZCrzemK7AHPXnZiTqEInuOlrT1hAHx/ 0cScduuZEBK7NlycEEtH6fCQY6eYKm5QdfafFyJR6vQ2pixcl71nlDD0oLmzcOaVKXXB mrWABK0CIrml2cA9EtM4hWB2OkrMxbSV+YzgeF3nlRvSIXEAalrfxxiuBSFYCVOHCN8v CUmH+vEvWu4tNyUoeU305GmjzyOuqFD7yzHeJcztPzBYZNnC2KCbqo7o55XXJON+lRTF pYNA== X-Gm-Message-State: AOAM532OIGRx4i4ts9LcR1m85eerEJZXTlCVXZGut5QbJ+1UFJYtbbjV ec2b+j/hBKPmQt5x1jtZh9wxURhHOrPNugvQs3BBcOplKw1zynt/200qqb7R0b2W59k9R6O5xhg BtG8S/oFwm3QI9X06iYBifo5J X-Received: by 2002:a1c:493:: with SMTP id 141mr3682735wme.172.1626342695232; Thu, 15 Jul 2021 02:51:35 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwxHnBTQd8EBvDvE+fh/H5JOd3n98Hv/0MLO3UGlbOtPJQDckheenHBNWf8+fW1YAIvzkbM/w== X-Received: by 2002:a1c:493:: with SMTP id 141mr3682713wme.172.1626342695002; Thu, 15 Jul 2021 02:51:35 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:5e2c:eb9a:a8b6:fd3e? ([2001:b07:6468:f312:5e2c:eb9a:a8b6:fd3e]) by smtp.gmail.com with ESMTPSA id b9sm7137793wrh.81.2021.07.15.02.51.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 15 Jul 2021 02:51:34 -0700 (PDT) Subject: Re: 5.13-rt1 + KVM = WARNING: at fs/eventfd.c:74 eventfd_signal() To: He Zhe , Daniel Bristot de Oliveira , Jason Wang , Thomas Gleixner , Sebastian Andrzej Siewior , "Michael S. Tsirkin" , Juri Lelli Cc: LKML , Al Viro References: <8dfc0ee9-b97a-8ca8-d057-31c8cad3f5b6@redhat.com> <475f84e2-78ee-1a24-ef57-b16c1f2651ed@redhat.com> From: Paolo Bonzini Message-ID: Date: Thu, 15 Jul 2021 11:51:32 +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 15/07/21 10:44, He Zhe wrote: > It was to increase the recursion depth to 2 so that vhost_worker and > kvm_vcpu_ioctl syscall could work in parallel The count is per-CPU, so parallel operations cannot cause it to become 2. Your patch might fix calls from ioeventfd to vhost_worker to another eventfd, but not *parallel* operation of KVM and vhost (except on PREEMPT_RT). You should identify the exact callstack that caused the warning for vDUSE, and document that one in the commit message, so that reviewers can understand the issue. Paolo