Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752486Ab0D1Mo6 (ORCPT ); Wed, 28 Apr 2010 08:44:58 -0400 Received: from mail-bw0-f219.google.com ([209.85.218.219]:44942 "EHLO mail-bw0-f219.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750788Ab0D1Mo5 (ORCPT ); Wed, 28 Apr 2010 08:44:57 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:from:to:subject:cc:date:message-id:user-agent:mime-version :content-type; b=POrTUQJl7ipQVbSGUpzx+VPDFXP7mPwMLRqUS/SPp1/jS06FNFcQQHx/Ih0xVbHxak qApKOm9l30bL8CNwfm5+AWyHV+enukaXuRJtCOudPEOAzQ/2D+3InrvjgCNoSKeaEHtL JE8VXhSwRDfGnotf1Jkn9GfXt5AaHDkjvSvW8= From: Dmitry Monakhov To: linux-kernel@vger.kernel.org Subject: CFQ is broken for CONFIG_BLK_CGROUP=y, CFQ_GROUP_IOSCHED=n CC: jens.axboe@oracle.com, Vivek Goyal Date: Wed, 28 Apr 2010 16:44:51 +0400 Message-ID: <877hnrg30c.fsf@openvz.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1089 Lines: 28 I've had an oops on kernel boot due to NULL pointer deference linux-2.6-block/for-next HEAD:7eaed1226ab411ee5dc8c34fc0d8034e4c98e3c6 I've enabled CONFIG_BLK_CGROUP, but not CFQ_GROUP_IOSCHED In this case cfq_ref_get_cfqg() defined as static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) { return NULL; } So following call trace is simply NOOP cfq_set_request() rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg); Which later result in OOPS on bio insertion cfq_insert_request -> blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,...) -> spin_lock_irqsave(&blkg->stats_lock, flags); Bad commit. >From 7f1dc8a2d2f45fc557b27fd56115338b1d34fc24 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Wed, 21 Apr 2010 17:44:16 +0200 Subject: [PATCH] blkio: Fix blkio crash during rq stat update -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/