On 09/07/2015 07:10 PM, Julien Grall wrote: > On 07/09/15 07:07, Bob Liu wrote: >> Hi Julien, > > Hi Bob, > >> On 09/04/2015 09:51 PM, Julien Grall wrote: >>> Hi Roger, >>> >>> On 04/09/15 11:08, Roger Pau Monne wrote: >>>> 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.gr...@citrix.com> >>>> Signed-off-by: Roger Pau Monné <roger....@citrix.com> >>>> Cc: Julien Grall <julien.gr...@citrix.com> >>>> Cc: Konrad Rzeszutek Wilk <konrad.w...@oracle.com> >>>> Cc: Boris Ostrovsky <boris.ostrov...@oracle.com> >>>> Cc: David Vrabel <david.vra...@citrix.com> >>>> Cc: xen-de...@lists.xenproject.org >>> >>> The patch is fixing my problem when using UEFI in the guest. Thank you! >>> >> >> Could you please explain the problem you met a bit more? >> So that I can know back port this patch if met similar issue. > > This is related to commit 86839c56dee28c315a4c19b7bfee450ccd84cd25 > "xen/block: add multi-page ring support" (Roger, it may be worth to > indicate the offending commit in you commit message). > > When starting a guest using UEFI. After the domain is destroyed I get > the following warning 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 ]--- > > This is because the allocation of the requests are done during the > connection but the free is done when the domain is destroyed. Therefore > if the domain is re-initializing the connection (because UEFI or PV Grub > is used), the request won't be free and kept until the end. >
Thank you! Roger, I think it's better to have this information in your commit message too. -- Regards, -Bob _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
