Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753535AbaF2UrH (ORCPT ); Sun, 29 Jun 2014 16:47:07 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43341 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751017AbaF2UrF (ORCPT ); Sun, 29 Jun 2014 16:47:05 -0400 Date: Sun, 29 Jun 2014 23:47:10 +0300 From: "Michael S. Tsirkin" To: Christoph Hellwig Cc: Josh Boyer , Rusty Russell , virtualization@lists.linux-foundation.org, "Linux-Kernel@Vger. Kernel. Org" , Brian Lane , Jens Axboe , Tejun Heo , John McCutchan , Robert Love , Eric Paris , Greg Kroah-Hartman Subject: Re: virt_blk BUG: sleeping function called from invalid context Message-ID: <20140629204710.GB11100@redhat.com> References: <20140629082637.GA23942@redhat.com> <20140629193222.GA7030@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140629193222.GA7030@lst.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jun 29, 2014 at 09:32:22PM +0200, Christoph Hellwig wrote: > On Sun, Jun 29, 2014 at 11:26:37AM +0300, Michael S. Tsirkin wrote: > > On Fri, Jun 27, 2014 at 07:57:38AM -0400, Josh Boyer wrote: > > > Hi All, > > > > > > We've had a report[1] of the virt_blk driver causing a lot of spew > > > because it's calling a sleeping function from an invalid context. The > > > backtrace is below. This is with kernel v3.16-rc2-69-gd91d66e88ea9. > > > > Hi Jens, pls see below - it looks like the call to blk_mq_end_io > > from IRQ context is causing the issue. > > IIUC you switched virtio to this from __blk_end_request_all in > > > > commit 1cf7e9c68fe84248174e998922b39e508375e7c1 > > virtio_blk: blk-mq support > > > > Is this always safe? > > I note that at least one other driver is doing this: > > drivers/block/mtip32xx/mtip32xx.c > > Just like __blk_end_request_all blk_mq_end_io is supposed to be called > from irq context. The problem is that the MD bio end_io handler is calling > a sleeping function. Not sure if that's a bug in MD though given the > kernfs symbols in the all trace and the recent churn in that area. My understanding is this: bitmap_endwrite -> calls sysfs_notify_dirent_safe under spinlock -> calls kernfs_notify which takes a mutex. So I am guessing it is this commit: commit d911d98748018f7c8facc035ba39c30f5cce6f9c Author: Tejun Heo Date: Wed Apr 9 11:07:31 2014 -0400 kernfs: make kernfs_notify() trigger inotify events too Tejun, what do you think? Josh, Brian, could you try reverting that commit to see if it helps? -- MST -- 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/