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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A23D2C4332F for ; Fri, 2 Dec 2022 18:28:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234405AbiLBS2G (ORCPT ); Fri, 2 Dec 2022 13:28:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234327AbiLBS2C (ORCPT ); Fri, 2 Dec 2022 13:28:02 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C65ECD9697 for ; Fri, 2 Dec 2022 10:27:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1670005623; 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=33ZyAUYenMjlLRX8QFd49i1YF8RHArF5TDtZ248qOZs=; b=hq6HTZ0dTxE3uQ3mmJXJsfUB6Wp2mHuJQZ1sUl84HnooBw4WZzk/Rj00MXoYClMlSrBMYd 7CPOWnFNsRGbLIB/z7WHvf+7445EpQ54cj0462hYEZG7ok7YUv6Qj510FJaFpI+4gTxqKo Joh1sLaI7fJXiRgvaQ9YjXeiLXFwoa0= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-492-hJbUHyphOtiXi1ev0jQyDg-1; Fri, 02 Dec 2022 13:27:02 -0500 X-MC-Unique: hJbUHyphOtiXi1ev0jQyDg-1 Received: by mail-wm1-f69.google.com with SMTP id c187-20020a1c35c4000000b003cfee3c91cdso2865595wma.6 for ; Fri, 02 Dec 2022 10:27:02 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=33ZyAUYenMjlLRX8QFd49i1YF8RHArF5TDtZ248qOZs=; b=akJjDuLk6ebpE8IhBv2n0phHeKc7nwpALR+OO4qOH8091f+9/1PUlhcirl6+28/2fB 9GvsDekEHX9gGWppLftuy173vtCFDzY9QmIpZtqhbyiO4VMEqKAUBdWgVXh0NvPK6w6h pTT+rs3Xbhth0fWp7Mpv9YxXdd9bWeeRylTKYTPuNSoqRFXwbfgM+jYN6Kmnhs/4NnKq +44YROU4fBgbhw5TxvsJn2SPjaIo2sPINHWg+pFE1LSZitOpMQCJ/d4BUED6UtNanYDy J/djaucu1n1gEVIjsf4Q9Xu6aumHk5J3NvkkFNX9voU3KqhHL4nJcdTP3Ew8Nsuw49tR 12wg== X-Gm-Message-State: ANoB5pkPVriY1b1Go8V2Laeu1FIdGdb3PvNBvI4ef0PwH6rzkUqSQjvP iX83JVdVkBF+ZLs3zY3tex10AzXhPks7DQn3NnSqigTCcZywvZ3YEKwqzWoC4xpj3M1d3PRXBA/ w7MCGNHvmNYFXmQo/+WAQHv9d X-Received: by 2002:a05:600c:4e4b:b0:3cf:7624:5fcd with SMTP id e11-20020a05600c4e4b00b003cf76245fcdmr52102166wmq.195.1670005621430; Fri, 02 Dec 2022 10:27:01 -0800 (PST) X-Google-Smtp-Source: AA0mqf7yV3q4cofRV+TOuSntrtid+pPem3DasxYocHnzyyHvYi0JJq2f7eoPijhRXyKG/bNkn/lg7g== X-Received: by 2002:a05:600c:4e4b:b0:3cf:7624:5fcd with SMTP id e11-20020a05600c4e4b00b003cf76245fcdmr52102158wmq.195.1670005621205; Fri, 02 Dec 2022 10:27:01 -0800 (PST) Received: from ?IPV6:2001:b07:6468:f312:9af8:e5f5:7516:fa89? ([2001:b07:6468:f312:9af8:e5f5:7516:fa89]) by smtp.googlemail.com with ESMTPSA id n10-20020adffe0a000000b00241bd7a7165sm7382927wrr.82.2022.12.02.10.27.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 02 Dec 2022 10:27:00 -0800 (PST) Message-ID: <8e8217f6-4eec-4793-637d-436a429c9aad@redhat.com> Date: Fri, 2 Dec 2022 19:26:59 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Subject: Re: [PATCH] KVM: Deal with nested sleeps in kvm_vcpu_block() Content-Language: en-US To: Space Meyer Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, kpsingh@kernel.org References: <20221130161946.3254953-1-spm@google.com> From: Paolo Bonzini In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/2/22 16:52, Space Meyer wrote: > The bug doesn't seem to be easily reproducible, but looking at the > code this should also be applicable for the upstream 6.0, 5.15, 5.10, > 5.4, 4.19 and 4.14 branches, which have not received a backport of > 26844fe. > > Do you think this is all we should do? My conclusion from the LWN > article was, that we should avoid the set_current_state -> > conditional -> schedule pattern when possible as well. Yes, the bug is there but unfortunately the backport is not easy. I don't really feel confident backporting the fix to older kernels; even if it is apparently just a couple lines of code, event handling is very delicate and has had a lot of changes recently. Paolo