Re: [workqueue] d5bff968ea: WARNING:at_kernel/workqueue.c:#process_one_work

[Paul E. McKenney]

On Thu, Jan 28, 2021 at 05:09:05PM +0800, Hillf Danton wrote:
> On Thu, 28 Jan 2021 15:52:40 +0800 Xing Zhengjun wrote:

[ . . . ]

> >I test the patch 4 times, no warning appears in the kernel log.
> 
> Thank you so much Zhengjun!
> 
> And the overall brain dump so far is
> 
> 1/ before and after d5bff968ea, changing the allowed ptr at online time
> is the key to quiesce the warning in process_one_work().
> 
> 2/ marking pcpu before changing aptr in rebind_workers() is mandatory in
> regards to cutting the risk of triggering such a warning.
> 
> 3/ we canot maintain such an order without quiescing the 508 warning for
> kworkers. And we have a couple of excuses to do so, a) the number of
> allowed CPUs is no longer checked in is_per_cpu_kthread() instead of
> PF_NO_SETAFFINITY, b) there is always a followup act to change the aptr
> in order to fix the number of aCPUs. 
> 
> 4/ same order is maintained also at rescue time.

Just out of curiosity, does this test still fail on current mainline?

							Thanx, Paul