On Tue, Feb 28, 2017 at 04:35:08PM +0800, Fengguang Wu wrote: > On Tue, Feb 28, 2017 at 09:17:11AM +0100, Peter Zijlstra wrote: > > On Tue, Feb 28, 2017 at 12:11:17PM +0800, Fengguang Wu wrote: > > > Hello, > > > > > > FYI, an old blk_mq bug triggers new warnings on this commit. It's very > > > reproducible and you may try the attached reproduce-* script. > > > > > [ 4.447772] kobject (ffff88001c041f10): tried to init an initialized object, something is seriously wrong. > > > [ 4.453395] CPU: 0 PID: 5 Comm: kworker/u2:0 Not tainted 4.10.0-01216-g29dee3c #2 > > > [ 4.455534] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-20161025_171302-gandalf 04/01/2014 > > > [ 4.458252] Workqueue: events_unbound async_run_entry_fn > > > [ 4.459708] Call Trace: > > > [ 4.460611] dump_stack+0x19/0x27 > > > [ 4.461652] kobject_init+0xda/0xf0 > > > [ 4.462731] blk_mq_register_dev+0x31/0x150 > > > [ 4.463990] blk_register_queue+0x205/0x250 > > > [ 4.465217] device_add_disk+0x1ab/0x710 > > > [ 4.466384] sd_probe_async+0x11c/0x1e0 > > > [ 4.467544] async_run_entry_fn+0xbd/0x220 > > > [ 4.468760] process_one_work+0x4a7/0x990 > > > [ 4.469938] ? process_one_work+0x348/0x990 > > > [ 4.471168] worker_thread+0x342/0x8a0 > > > [ 4.472300] ? process_one_work+0x990/0x990 > > > [ 4.473540] kthread+0x188/0x190 > > > [ 4.474557] ? kthread_create_on_node+0x40/0x40 > > > [ 4.475850] ret_from_fork+0x31/0x40 > > > > So this was pre-existing wreckage? If so, that needs to be sorted first. > > Because if the kobject stuff is broken, there's no way the refcount > > stuff can begin to work. > > Yeah it's old bug that should have existed for quite some time. > It's not quite related to the refcount work, just hoping the new > warning might serve as new clues to help debugging the blk_mq bug. > > Thanks, > Fengguang Ming Lei posted a series to fix this here [1]. I haven't gotten around to testing it, but it'd be great if you could try it, too. http://marc.info/?l=linux-block&m=148775846217069&w=2
