Received: by 2002:ac0:a5a6:0:0:0:0:0 with SMTP id m35-v6csp1377075imm; Thu, 6 Sep 2018 22:19:22 -0700 (PDT) X-Google-Smtp-Source: ANB0VdZdPiTphd3/zXUjh5tTh7kofF+D0lcGvAwbH5dpTQMGaknc0tH1umb1KpmEy9ZTZ4tz92u2 X-Received: by 2002:a63:b705:: with SMTP id t5-v6mr5982777pgf.366.1536297562632; Thu, 06 Sep 2018 22:19:22 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1536297562; cv=none; d=google.com; s=arc-20160816; b=hLt5EUb7xk84qk81NYMtGkOhKxN8CtNM3ci+ybW/hYjq5OdsztjGF9ESi2CU65yBo6 arnk9crbY2BftTQasgcOv1vH0CM8Vrs4W+1QNxQcfYvmLMZy1yX/CzTEVi4JddmpmL/y PV0/sHVUbDDC6ytsQDFFGw9PqABqKnYvO21c/KZLbXbjtY80Ly8pVhSSIi9ZeW5J+z5/ 5HgO4kKgyDKgjDV/PBKqd8sfjXEpxeBjnxz3b8aNDqbKtxIaMiHahlY2kSXx1YN7tkzj JErVclZxqLqB/nKRbmCl3D8SLGkzrIqTzipCd+ul33E7Y/rsKwiNodIkS5VYQZLAvQ9X HCww== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding :content-language:in-reply-to:mime-version:user-agent:date :message-id:autocrypt:openpgp:from:references:cc:to:subject; bh=GRQm1bkRca14tI+ALzhosWb+mSjusjdYoKZPUw7RzPI=; b=N1QVFdWkgr1m/TsWGsXC4BkoQ1oTiJVoSvgd2HdD6XZ+MoNVaSbU2taOy0S9ETbcCH F7Pz9K2W7VAwUfLXRLqibx/bJVKsBjC5g62kHLByeF3Hp9sz98Dr7Ic2ZZeaiUvqAgbU C3mBJXyNYTaNB0PzgwYnd8ywT+9iWIt3bsGe8cAh8uJlD5/ygJHXELwrzLt77HnPP27I dmPlvRma1sw5DHP9GAdBINShKVmISZNw8RNE++9hO2S18zWrzEmdx+OWSAbl5HX86hqo MrT7XM3VCvshqLeWBl1t0rhNSepGdV5OQj2YGOWZpIDqINLfcgPeA3GR2ozggvsvxfA+ wcuA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id q197-v6si7446930pgq.526.2018.09.06.22.19.07; Thu, 06 Sep 2018 22:19:22 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727618AbeIGJyh (ORCPT + 99 others); Fri, 7 Sep 2018 05:54:37 -0400 Received: from mx2.suse.de ([195.135.220.15]:56882 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725831AbeIGJyh (ORCPT ); Fri, 7 Sep 2018 05:54:37 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id CFCE4AEBA; Fri, 7 Sep 2018 05:15:23 +0000 (UTC) Subject: Re: [PATCH v2] xen: avoid crash in disable_hotplug_cpu To: Olaf Hering , Boris Ostrovsky Cc: xen-devel@lists.xenproject.org, open list References: <20180906063712.28639-1-olaf@aepfle.de> <20180906223145.37f7009b.olaf@aepfle.de> From: Juergen Gross Openpgp: preference=signencrypt Autocrypt: addr=jgross@suse.com; prefer-encrypt=mutual; keydata= xsBNBFOMcBYBCACgGjqjoGvbEouQZw/ToiBg9W98AlM2QHV+iNHsEs7kxWhKMjrioyspZKOB ycWxw3ie3j9uvg9EOB3aN4xiTv4qbnGiTr3oJhkB1gsb6ToJQZ8uxGq2kaV2KL9650I1SJve dYm8Of8Zd621lSmoKOwlNClALZNew72NjJLEzTalU1OdT7/i1TXkH09XSSI8mEQ/ouNcMvIJ NwQpd369y9bfIhWUiVXEK7MlRgUG6MvIj6Y3Am/BBLUVbDa4+gmzDC9ezlZkTZG2t14zWPvx XP3FAp2pkW0xqG7/377qptDmrk42GlSKN4z76ELnLxussxc7I2hx18NUcbP8+uty4bMxABEB AAHNHkp1ZXJnZW4gR3Jvc3MgPGpncm9zc0BzdXNlLmRlPsLAeQQTAQIAIwUCU4xw6wIbAwcL CQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJELDendYovxMvi4UH/Ri+OXlObzqMANruTd4N zmVBAZgx1VW6jLc8JZjQuJPSsd/a+bNr3BZeLV6lu4Pf1Yl2Log129EX1KWYiFFvPbIiq5M5 kOXTO8Eas4CaScCvAZ9jCMQCgK3pFqYgirwTgfwnPtxFxO/F3ZcS8jovza5khkSKL9JGq8Nk czDTruQ/oy0WUHdUr9uwEfiD9yPFOGqp4S6cISuzBMvaAiC5YGdUGXuPZKXLpnGSjkZswUzY d9BVSitRL5ldsQCg6GhDoEAeIhUC4SQnT9SOWkoDOSFRXZ+7+WIBGLiWMd+yKDdRG5RyP/8f 3tgGiB6cyuYfPDRGsELGjUaTUq3H2xZgIPfOwE0EU4xwFgEIAMsx+gDjgzAY4H1hPVXgoLK8 B93sTQFN9oC6tsb46VpxyLPfJ3T1A6Z6MVkLoCejKTJ3K9MUsBZhxIJ0hIyvzwI6aYJsnOew cCiCN7FeKJ/oA1RSUemPGUcIJwQuZlTOiY0OcQ5PFkV5YxMUX1F/aTYXROXgTmSaw0aC1Jpo w7Ss1mg4SIP/tR88/d1+HwkJDVW1RSxC1PWzGizwRv8eauImGdpNnseneO2BNWRXTJumAWDD pYxpGSsGHXuZXTPZqOOZpsHtInFyi5KRHSFyk2Xigzvh3b9WqhbgHHHE4PUVw0I5sIQt8hJq 5nH5dPqz4ITtCL9zjiJsExHuHKN3NZsAEQEAAcLAXwQYAQIACQUCU4xwFgIbDAAKCRCw3p3W KL8TL0P4B/9YWver5uD/y/m0KScK2f3Z3mXJhME23vGBbMNlfwbr+meDMrJZ950CuWWnQ+d+ Ahe0w1X7e3wuLVODzjcReQ/v7b4JD3wwHxe+88tgB9byc0NXzlPJWBaWV01yB2/uefVKryAf AHYEd0gCRhx7eESgNBe3+YqWAQawunMlycsqKa09dBDL1PFRosF708ic9346GLHRc6Vj5SRA UTHnQqLetIOXZm3a2eQ1gpQK9MmruO86Vo93p39bS1mqnLLspVrL4rhoyhsOyh0Hd28QCzpJ wKeHTd0MAWAirmewHXWPco8p1Wg+V+5xfZzuQY0f4tQxvOpXpt4gQ1817GQ5/Ed/wsDtBBgB CAAgFiEEhRJncuj2BJSl0Jf3sN6d1ii/Ey8FAlrd8NACGwIAgQkQsN6d1ii/Ey92IAQZFggA HRYhBFMtsHpB9jjzHji4HoBcYbtP2GO+BQJa3fDQAAoJEIBcYbtP2GO+TYsA/30H/0V6cr/W V+J/FCayg6uNtm3MJLo4rE+o4sdpjjsGAQCooqffpgA+luTT13YZNV62hAnCLKXH9n3+ZAgJ RtAyDWk1B/0SMDVs1wxufMkKC3Q/1D3BYIvBlrTVKdBYXPxngcRoqV2J77lscEvkLNUGsu/z W2pf7+P3mWWlrPMJdlbax00vevyBeqtqNKjHstHatgMZ2W0CFC4hJ3YEetuRBURYPiGzuJXU pAd7a7BdsqWC4o+GTm5tnGrCyD+4gfDSpkOT53S/GNO07YkPkm/8J4OBoFfgSaCnQ1izwgJQ jIpcG2fPCI2/hxf2oqXPYbKr1v4Z1wthmoyUgGN0LPTIm+B5vdY82wI5qe9uN6UOGyTH2B3p hRQUWqCwu2sqkI3LLbTdrnyDZaixT2T0f4tyF5Lfs+Ha8xVMhIyzNb1byDI5FKCb Message-ID: Date: Fri, 7 Sep 2018 07:15:22 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180906223145.37f7009b.olaf@aepfle.de> Content-Type: text/plain; charset=windows-1252 Content-Language: de-DE Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/09/18 22:31, Olaf Hering wrote: > Am Thu, 6 Sep 2018 14:45:57 -0400 > schrieb Boris Ostrovsky : > >> On 09/06/2018 02:37 AM, Olaf Hering wrote: >>> The command 'xl vcpu-set 0 0', issued in dom0, will crash dom0: > >>> This happens because handle_vcpu_hotplug_event is called twice. In the >>> first iteration cpu_present is still true, in the second iteration >>> cpu_present is false which causes get_cpu_device to return NULL. >>> In case of cpu#0, cpu_online is apparently always true. > >> I think we should check both this and num_online_cpus() != 0. > > This can not possibly help. cpu#0 is the first one that goes offline. > IF cpu0_hotpluggable is broken, then only "if (!cpu) return;" can help. We should add the Xen PV guest test to arch_register_cpu() and switch cpu0_hotpluggable off. Juergen