From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932374AbZD3R1N (ORCPT ); Thu, 30 Apr 2009 13:27:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1764609AbZD3RIA (ORCPT ); Thu, 30 Apr 2009 13:08:00 -0400 Received: from kroah.org ([198.145.64.141]:56378 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1764591AbZD3RHw (ORCPT ); Thu, 30 Apr 2009 13:07:52 -0400 X-Mailbox-Line: From gregkh@mini.kroah.org Thu Apr 30 09:57:45 2009 Message-Id: <20090430165744.892174136@mini.kroah.org> User-Agent: quilt/0.48-1 Date: Thu, 30 Apr 2009 09:56:33 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , Willy Tarreau , Rodrigo Rubira Branco , Jake Edge , Eugene Teo , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, FUJITA Tomonori , Douglas Gilbert , James Bottomley , Chris Wright Subject: [patch 44/88] SCSI: sg: avoid blk_put_request/blk_rq_unmap_user in interrupt References: <20090430165549.117010404@mini.kroah.org> Content-Disposition: inline; filename=0074-SCSI-sg-avoid-blk_put_request-blk_rq_unmap_user-in.patch In-Reply-To: <20090430170122.GA16015@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.28-stable review patch. If anyone has any objections, please let us know. ------------------ From: FUJITA Tomonori upstream commit: c96952ed7031e7c576ecf90cf95b8ec099d5295a This fixes the following oops: http://marc.info/?l=linux-kernel&m=123316111415677&w=2 You can reproduce this bug by interrupting a program before a sg response completes. This leads to the special sg state (the orphan state), then sg calls blk_put_request in interrupt (rq->end_io). The above bug report shows the recursive lock problem because sg calls blk_put_request in interrupt. We could call __blk_put_request here instead however we also need to handle blk_rq_unmap_user here, which can't be called in interrupt too. In the orphan state, we don't need to care about the data transfer (the program revoked the command) so adding 'just free the resource' mode to blk_rq_unmap_user is a possible option. I prefer to avoid complicating the blk mapping API when possible. I change the orphan state to call sg_finish_rem_req via execute_in_process_context. We hold sg_fd->kref so sg_fd doesn't go away until keventd_wq finishes our work. copy_from_user/to_user fails so blk_rq_unmap_user just frees the resource without the data transfer. Signed-off-by: FUJITA Tomonori Acked-by: Douglas Gilbert Signed-off-by: James Bottomley Signed-off-by: Chris Wright Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/sg.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -138,6 +138,7 @@ typedef struct sg_request { /* SG_MAX_QU volatile char done; /* 0->before bh, 1->before read, 2->read */ struct request *rq; struct bio *bio; + struct execute_work ew; } Sg_request; typedef struct sg_fd { /* holds the state of a file descriptor */ @@ -1234,6 +1235,15 @@ sg_mmap(struct file *filp, struct vm_are return 0; } +static void sg_rq_end_io_usercontext(struct work_struct *work) +{ + struct sg_request *srp = container_of(work, struct sg_request, ew.work); + struct sg_fd *sfp = srp->parentfp; + + sg_finish_rem_req(srp); + kref_put(&sfp->f_ref, sg_remove_sfp); +} + /* * This function is a "bottom half" handler that is called by the mid * level when a command is completed (or has failed). @@ -1312,10 +1322,9 @@ static void sg_rq_end_io(struct request */ wake_up_interruptible(&sfp->read_wait); kill_fasync(&sfp->async_qp, SIGPOLL, POLL_IN); + kref_put(&sfp->f_ref, sg_remove_sfp); } else - sg_finish_rem_req(srp); /* call with srp->done == 0 */ - - kref_put(&sfp->f_ref, sg_remove_sfp); + execute_in_process_context(sg_rq_end_io_usercontext, &srp->ew); } static struct file_operations sg_fops = {