From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Linux 3.0 oopses when pulling a USB CDROM Date: Fri, 1 Jul 2011 10:05:31 -0700 Message-ID: <20110701170531.GA3693@tassilo.jf.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mga01.intel.com ([192.55.52.88]:29879 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753516Ab1GARGy (ORCPT ); Fri, 1 Jul 2011 13:06:54 -0400 Content-Disposition: inline Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Cc: axboe@kernel.dk, rjw@sisk.pl Hi, I found I can reliably crash a 3.0 system by pulling the USB cable of a mounted USB cdrom (or rather a USB device which has a builtin fake CD-ROM) I suspect it's a regression too. It ends with a NULL pointer reference on a NULL sdev in scsi_prep_state_check. Here's a somewhat incomplete backtrace (written down by hand) scsi_prep_state_check scsi_setup_blk_pc_cmnd blk_peek_request ... scsi_request_fn ... ioctl_internal_command ... scsi_set_medium_removal sr_lock_door cdrom_release ... umount I tried adding a if (!sdev) return BLKPREP_KILL; to scsi_prep_state_check, but that caused a RCU CPU stall and a generally unhappy system instead. The sdev must be still there in scsi_set_medium_removal because it's referenced, so it must get lost somewhere in SCSI or in the block layer. Any ideas how to fix this? -Andi -- ak@linux.intel.com -- Speaking for myself only