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. So I think this should be backported in Linux 4.2 where the patch has been introduced. Regards, -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
