Re: [LKP] [blk_mq_register_hctx] 29dee3c03a WARNING: CPU: 0 PID: 5 at lib/refcount.c:114 refcount_inc

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.