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[209.132.180.67]) by mx.google.com with ESMTP id 88-v6si1987654plb.57.2018.10.30.00.05.36; Tue, 30 Oct 2018 00:05:51 -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 S1727065AbeJ3P5C (ORCPT + 99 others); Tue, 30 Oct 2018 11:57:02 -0400 Received: from mx2.suse.de ([195.135.220.15]:56814 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726222AbeJ3P5B (ORCPT ); Tue, 30 Oct 2018 11:57:01 -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 1B153AF04; Tue, 30 Oct 2018 07:04:44 +0000 (UTC) Subject: Re: [PATCH] xen-blkfront: fix kernel panic with negotiate_mq error path To: Manjunath Patil , boris.ostrovsky@oracle.com, konrad.wilk@oracle.com, roger.pau@citrix.com Cc: axboe@kernel.dk, xen-devel@lists.xenproject.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <1540837916-14356-1-git-send-email-manjunath.b.patil@oracle.com> 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: <65b5d648-d9dc-9248-751c-b6e15109b52e@suse.com> Date: Tue, 30 Oct 2018 08:04:42 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <1540837916-14356-1-git-send-email-manjunath.b.patil@oracle.com> Content-Type: text/plain; charset=utf-8 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 29/10/2018 19:31, Manjunath Patil wrote: > info->nr_rings isn't adjusted in case of ENOMEM error from > negotiate_mq(). This leads to kernel panic in error path. > > Typical call stack involving panic - > #8 page_fault at ffffffff8175936f > [exception RIP: blkif_free_ring+33] > RIP: ffffffffa0149491 RSP: ffff8804f7673c08 RFLAGS: 00010292 > ... > #9 blkif_free at ffffffffa0149aaa [xen_blkfront] > #10 talk_to_blkback at ffffffffa014c8cd [xen_blkfront] > #11 blkback_changed at ffffffffa014ea8b [xen_blkfront] > #12 xenbus_otherend_changed at ffffffff81424670 > #13 backend_changed at ffffffff81426dc3 > #14 xenwatch_thread at ffffffff81422f29 > #15 kthread at ffffffff810abe6a > #16 ret_from_fork at ffffffff81754078 > > Though either of my changes avoid the panic, I included both the > changes. This issue got introduced with "7ed8ce1 xen-blkfront: move > negotiate_mq to cover all cases of new VBDs" Please us the correct format for specifying another commit. > Signed-off-by: Manjunath Patil Can you please add a "Fixes:" tag and "Cc: stable@vger.kernel.org" ? > --- > drivers/block/xen-blkfront.c | 7 +++++-- > 1 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c > index 429d201..dc8fe25 100644 > --- a/drivers/block/xen-blkfront.c > +++ b/drivers/block/xen-blkfront.c > @@ -1350,8 +1350,10 @@ static void blkif_free(struct blkfront_info *info, int suspend) > if (info->rq) > blk_mq_stop_hw_queues(info->rq); > > - for (i = 0; i < info->nr_rings; i++) > - blkif_free_ring(&info->rinfo[i]); > + if (info->rinfo) { > + for (i = 0; i < info->nr_rings; i++) > + blkif_free_ring(&info->rinfo[i]); > + } I'd drop this change. > > kfree(info->rinfo); > info->rinfo = NULL; > @@ -1919,6 +1921,7 @@ static int negotiate_mq(struct blkfront_info *info) > GFP_KERNEL); > if (!info->rinfo) { > xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure"); > + info->nr_rings = 0; > return -ENOMEM; > } Juergen