From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7CC7253BE for ; Wed, 4 Dec 2024 01:39:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733276396; cv=none; b=cN0LJpCjXgMuQn9QMfD94SXpVlHOXUCzqQZtT5gzHDkwL8nn8iRWc+7L4o92NwWEkH5dv2z7eJ+WQD+NfBs+Nz7AuYxiXm25/+6nMkaF/9YT9aEp0SO6IhqfLt/7KygHkawnwtuYxn18ND2Trscvvv2yP3RiI4jSZrCcR8uYbyo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733276396; c=relaxed/simple; bh=5Ol0rnel7frJYPWxR6WOOs6MvPTLmEjvI5btrLgxu5Q=; h=From:Message-ID:Date:MIME-Version:Subject:To:Cc:References: In-Reply-To:Content-Type; b=pmwfIbkrlB3iKRe8WmJorqfsjqgbtgSgPlKagruzfliubrU/RmFnPCzhOxRRKBY/1wkp4yIiwovZbklTiFjNtExxygcnRzdPcQ4E81ztWh3AvkviH2nglFd4IZN7KCAbC7zIu3lFveU5DVotEpLfR5X5F7W9Yw7HGG2QQGNLXjw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=IyajlRYL; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="IyajlRYL" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1733276391; 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=5Ol0rnel7frJYPWxR6WOOs6MvPTLmEjvI5btrLgxu5Q=; b=IyajlRYLmvSD3xlCbyEnn4e8941l2CmZKUonJ/09IFnkOPFWJ0lW7QVUCKZ0M7EfYOTHLJ bBU9HwpY+QYm9uHFEmUe+vwiuHVQW8CBCGFtUnRZPMYLmeosP7rcgOX1JoPPEJGZs9s9dn Pps7+lYyc0EOcQQR1ZAgJ9s7Ub9Bh/4= Received: from mail-io1-f72.google.com (mail-io1-f72.google.com [209.85.166.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-627-vSmc8fhTM-CmzRiPBBRO7A-1; Tue, 03 Dec 2024 20:39:50 -0500 X-MC-Unique: vSmc8fhTM-CmzRiPBBRO7A-1 X-Mimecast-MFC-AGG-ID: vSmc8fhTM-CmzRiPBBRO7A Received: by mail-io1-f72.google.com with SMTP id ca18e2360f4ac-843dd952aa7so601918239f.2 for ; Tue, 03 Dec 2024 17:39:50 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1733276389; x=1733881189; h=content-transfer-encoding:in-reply-to:content-language:references :cc:to:subject:user-agent:mime-version:date:message-id:from :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=5Ol0rnel7frJYPWxR6WOOs6MvPTLmEjvI5btrLgxu5Q=; b=TsHNYnAm+0fH9hsvbjdttiMM4N5F1MyG/0i7louhiQnheJqlyBTMI7br5LBKpKo4Hh bYtNxROgsjqrSocGVwwY4SXivzIwiPrPfMoLHTc2VeFsAKIZM7eqWJOpNuiuNhBJv1rF J+FFHsQIoe+D5cW0mO0biCR3fBKJnIm+N6y900oSTNHRVUMtXMB4Mvf4T/HWieKK6OS8 ayLtcdIkafgnAXGIngOQAbpPMV+26xqQkhM2rq7NQHcaouJNPi2nFZYqrZyiSsl61xpW smk5bwDaABRteQ3afbuP95e/g+kS/sgfEszzBVKDwFyJf9go8U4KkzcK3T0Zp7JL1OHk y5yQ== X-Forwarded-Encrypted: i=1; AJvYcCVaRHn5VJtNJB02JCwtF9A6cGY0n9O45eV6Qzy7o+foRzVd4hN6Y/glkdBik6UtSWyuQQXLYh+9Osok01Y=@vger.kernel.org X-Gm-Message-State: AOJu0Yx6lxp4Xk5hTChJQQkfK+L9ZQ/sErCA8G48FHqVqB3lnV8eySl+ 6TzKNpz4f5nVF46+yoAcVezMcmEywoUFmQN3I7vdOcOc1dgbOc21I2RtI0UcKHgL8UzfBWHcW7b 5T2s0eij6FhUBCbNxuIkNeYDVpg8zQAiD0WIAG/3fqf1w2dPYfcxDmYHRfosSYw== X-Gm-Gg: ASbGncs7TD9x6/9G82YTDc1h30t10Uc4xjentMudITQnGLrNB+QdU59j/tJsp/nG/P+ iqbasfSCrYnKA4jESVJzCO+sDCx6sUN8VH0Y2cBRFRXa1t5ripULiOBE+1nhOBQRiPedNHCxrEz sUJ6wTklgbUTNPr1HpupT13M16wK8QsQAZvUWru7M3v+RCqoDK8wFEyRtX/e/o/YrJH3NJId3G4 KX/w+PnOuYNdSFD+VrRKMh1Y35otY4SCEhjIvYWUUagfjK/RlgdGZFk8uk9WIyNu5ggbmMAcJdd qh7/sE15jcakIfXQMw== X-Received: by 2002:a05:6602:6c0a:b0:83a:9f64:6c75 with SMTP id ca18e2360f4ac-8445b53ee22mr672219339f.3.1733276389465; Tue, 03 Dec 2024 17:39:49 -0800 (PST) X-Google-Smtp-Source: AGHT+IErCvEkrixCbhbL7MtaDL5770KrUB2GnE5McK3ptHue31aNm1KT+phjOo8E4QiNVeG2NpNz/w== X-Received: by 2002:a05:6602:6c0a:b0:83a:9f64:6c75 with SMTP id ca18e2360f4ac-8445b53ee22mr672218239f.3.1733276389188; Tue, 03 Dec 2024 17:39:49 -0800 (PST) Received: from ?IPV6:2601:188:ca00:a00:f844:fad5:7984:7bd7? ([2601:188:ca00:a00:f844:fad5:7984:7bd7]) by smtp.gmail.com with ESMTPSA id 8926c6da1cb9f-4e230e908b4sm2771705173.158.2024.12.03.17.39.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 03 Dec 2024 17:39:48 -0800 (PST) From: Waiman Long X-Google-Original-From: Waiman Long Message-ID: <0467ac99-dd3d-410a-8326-df4396d0cabb@redhat.com> Date: Tue, 3 Dec 2024 20:39:45 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] x86/nmi: Add an emergency handler in nmi_desc & use it in nmi_shootdown_cpus() To: Rik van Riel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Peter Zijlstra Cc: x86@kernel.org, linux-kernel@vger.kernel.org, "H. Peter Anvin" References: <20241203150732.182065-1-longman@redhat.com> Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 12/3/24 8:00 PM, Rik van Riel wrote: > On Tue, 2024-12-03 at 10:07 -0500, Waiman Long wrote: >> Another way to fix this problem while allowing panic() calls from >> NMI context is by adding a new emergency NMI handler to the nmi_desc >> structure and provide a new set_emergency_nmi_handler() helper to >> atomically set crash_nmi_callback() in any context. The new emergency >> handler will be invoked first before other handlers in the linked >> list. That will eliminate the need to take any lock and serve the >> panic >> in NMI use case. >> >> Signed-off-by: Waiman Long > I've seen that panic come by a number of times, but > never came up with a good fix. > > Your idea certainly looks like it should work, and > avoid all the issues along the way. > > Acked-by: Rik van Riel Thanks for the review. Cheers, Longman