On Wed, Aug 04, 2021 at 01:00:57PM +0200, Sebastian Andrzej Siewior wrote:
> On 2021-08-04 12:48:05 [+0200], To Daniel Wagner wrote:
> > On 2021-08-04 12:43:42 [+0200], To Daniel Wagner wrote:
> > > Odd. Do you have a config for that, please?
> >
> > No need.
> > | [ 90.202543] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:35
> > | [ 90.202549] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 2047, name: iou-wrk-2041
> > | [ 90.202555] CPU: 5 PID: 2047 Comm: iou-wrk-2041 Tainted: G W 5.14.0-rc4-rt4+ #89
> > | [ 90.202561] Call Trace:
> …
> > | [ 90.202588] rt_spin_lock+0x19/0x70
> > | [ 90.202593] ___slab_alloc+0xcb/0x7d0
> …
> > | [ 90.202618] kmem_cache_alloc_trace+0x79/0x1f0
> > | [ 90.202621] io_wqe_dec_running.isra.0+0x98/0xe0
> > | [ 90.202625] io_wq_worker_sleeping+0x37/0x50
> > | [ 90.202628] schedule+0x30/0xd0
> >
> > le look.
>
> So this is due to commit
> 685fe7feedb96 ("io-wq: eliminate the need for a manager thread")
>
> introduced in the v5.13-rc1 merge window. The call chain is
> schedule()
> sched_submit_work()
> preempt_disable();
> io_wq_worker_sleeping()
> raw_spin_lock_irq(&worker->wqe->lock);
> io_wqe_dec_running(worker);
> io_queue_worker_create()
> kmalloc(sizeof(*cwd), GFP_ATOMIC);
>
> The lock wqe::lock has been turned into a raw_spinlock_t in commit
> 95da84659226d ("io_wq: Make io_wqe::lock a raw_spinlock_t")
>
> after a careful analysis of the code at that time. This commit breaks
> things. Is this really needed?
Urgh, doing allocs from schedule seems really yuck. Can we please not do
this?
