Messages in this thread | | | Date | Mon, 14 Feb 2022 07:34:42 -1000 | From | Tejun Heo <> | Subject | Re: [syzbot] possible deadlock in worker_thread |
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Hello,
On Mon, Feb 14, 2022 at 10:36:57PM +0900, Tetsuo Handa wrote: > OK. Then, I propose below patch. If you are OK with this approach, I can > keep this via my tree as a linux-next only experimental patch for one or > two weeks, in order to see if someone complains.
I don't mind you testing that way but this and would much prefer this and related changes in the wq tree.
> +static void warn_if_flushing_global_workqueue(struct workqueue_struct *wq) > +{ > +#ifdef CONFIG_PROVE_LOCKING > + static DEFINE_RATELIMIT_STATE(flush_warn_rs, 600 * HZ, 1); > + const char *name; > + > + if (wq == system_wq) > + name = "system_wq"; > + else if (wq == system_highpri_wq) > + name = "system_highpri_wq"; > + else if (wq == system_long_wq) > + name = "system_long_wq"; > + else if (wq == system_unbound_wq) > + name = "system_unbound_wq"; > + else if (wq == system_freezable_wq) > + name = "system_freezable_wq"; > + else if (wq == system_power_efficient_wq) > + name = "system_power_efficient_wq"; > + else if (wq == system_freezable_power_efficient_wq) > + name = "system_freezable_power_efficient_wq"; > + else > + return; > + ratelimit_set_flags(&flush_warn_rs, RATELIMIT_MSG_ON_RELEASE); > + if (!__ratelimit(&flush_warn_rs)) > + return; > + pr_warn("Since system-wide WQ is shared, flushing system-wide WQ can introduce unexpected locking dependency. Please replace %s usage in your code with your local WQ.\n", > + name); > + dump_stack(); > +#endif
Instead of doing the above, please add a wq flag to mark system wqs and trigger the warning that way and I'd leave it regardless of PROVE_LOCKING.
Thanks.
-- tejun
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