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From: Christoph Hellwig <hch@lst.de>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Josh Boyer <jwboyer@fedoraproject.org>,
	Rusty Russell <rusty@rustcorp.com.au>,
	virtualization@lists.linux-foundation.org,
	"Linux-Kernel@Vger. Kernel. Org" <linux-kernel@vger.kernel.org>,
	Brian Lane <bcl@redhat.com>, Jens Axboe <axboe@kernel.dk>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: virt_blk BUG: sleeping function called from invalid context
Date: Sun, 29 Jun 2014 21:32:22 +0200	[thread overview]
Message-ID: <20140629193222.GA7030@lst.de> (raw)
In-Reply-To: <20140629082637.GA23942@redhat.com>

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.


  reply	other threads:[~2014-06-29 19:32 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-06-27 11:57 virt_blk BUG: sleeping function called from invalid context Josh Boyer
2014-06-29  8:26 ` Michael S. Tsirkin
2014-06-29 19:32   ` Christoph Hellwig [this message]
2014-06-29 20:47     ` Michael S. Tsirkin
2014-06-29 20:55       ` Jens Axboe
2014-06-30 20:17         ` Tejun Heo
2014-07-01 20:41           ` [PATCH driver-core-linus] kernfs: kernfs_notify() must be useable from non-sleepable contexts Tejun Heo
2014-07-01 20:51             ` Greg Kroah-Hartman
2014-07-02 14:14               ` Tejun Heo
2014-07-02 16:31                 ` Greg Kroah-Hartman
2014-07-02  5:53             ` Michael S. Tsirkin

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