Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [stabe-rc 5.9 ] sched: core.c:7270 Illegal context switch in RCU-bh read-side critical section! | Date | Wed, 16 Dec 2020 16:21:12 +0100 |
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On Wed, Dec 16 2020 at 15:55, Naresh Kamboju wrote: > On Tue, 15 Dec 2020 at 23:52, Jakub Kicinski <kuba@kernel.org> wrote: >> > Or you could place checks for being in a BH-disable further up in >> > the code. Or build with CONFIG_DEBUG_INFO=y to allow more precise >> > interpretation of this stack trace. > > I will try to reproduce this warning with DEBUG_INFO=y enabled kernel and > get back to you with a better crash log. > >> >> My money would be on the option that whatever run on this workqueue >> before forgot to re-enable BH, but we already have a check for that... >> Naresh, do you have the full log? Is there nothing like "BUG: workqueue >> leaked lock" above the splat?
No, because it's in the middle of the work. The workqueue bug triggers when the work has finished.
So cleanup_up() net does
.... synchronize_rcu(); <- might sleep. So up to here it should be fine.
list_for_each_entry_continue_reverse(ops, &pernet_list, list) ops_exit_list(ops, &net_exit_list);
ops_exit_list() is called for each ops which then either invokes ops->exit() or ops->exit_batch().
So one of those callbacks fails to reenable BH, so adding a check after each invocation of ops->exit() and ops->exit_batch() for !local_bh_disabled() should be able to identify the buggy callback.
Thanks,
tglx
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