Roger Pau Monne f929d42ceb xen/blkback: free requests on disconnection ... This is due to commit 86839c56de "xen/block: add multi-page ring support" When using an guest under UEFI - after the domain is destroyed the following warning comes from blkback. ------------[ cut here ]------------ WARNING: CPU: 2 PID: 95 at /home/julien/works/linux/drivers/block/xen-blkback/xenbus.c:274 xen_blkif_deferred_free+0x1f4/0x1f8() Modules linked in: CPU: 2 PID: 95 Comm: kworker/2:1 Tainted: G W 4.2.0 #85 Hardware name: APM X-Gene Mustang board (DT) Workqueue: events xen_blkif_deferred_free Call trace: [<ffff8000000890a8>] dump_backtrace+0x0/0x124 [<ffff8000000891dc>] show_stack+0x10/0x1c [<ffff8000007653bc>] dump_stack+0x78/0x98 [<ffff800000097e88>] warn_slowpath_common+0x9c/0xd4 [<ffff800000097f80>] warn_slowpath_null+0x14/0x20 [<ffff800000557a0c>] xen_blkif_deferred_free+0x1f0/0x1f8 [<ffff8000000ad020>] process_one_work+0x160/0x3b4 [<ffff8000000ad3b4>] worker_thread+0x140/0x494 [<ffff8000000b2e34>] kthread+0xd8/0xf0 ---[ end trace 6f859b7883c88cdd ]--- Request allocation has been moved to connect_ring, which is called every time blkback connects to the frontend (this can happen multiple times during a blkback instance life cycle). On the other hand, request freeing has not been moved, so it's only called when destroying the backend instance. Due to this mismatch, blkback can allocate the request pool multiple times, without freeing it. In order to fix it, move the freeing of requests to xen_blkif_disconnect to restore the symmetry between request allocation and freeing. Reported-by: Julien Grall <julien.grall@citrix.com> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com> Tested-by: Julien Grall <julien.grall@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: xen-devel@lists.xenproject.org CC: stable@vger.kernel.org # 4.2 Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>		2015-09-23 12:09:19 -04:00
..
blkback.c	xen: features and cleanups for 4.2-rc0	2015-07-01 11:53:46 -07:00
common.h	xen: features and cleanups for 4.2-rc0	2015-07-01 11:53:46 -07:00
Makefile	xen/blkback: Squash vbd.c,interface.c in blkback.c and xenbus.c respectivly.	2011-04-20 11:57:59 -04:00
xenbus.c	xen/blkback: free requests on disconnection	2015-09-23 12:09:19 -04:00