Messages in this thread | | | Date | Thu, 1 Dec 2022 13:56:50 -0800 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH printk v5 03/40] printk: Prepare for SRCU console list protection |
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On Thu, Dec 01, 2022 at 10:42:25PM +0106, John Ogness wrote: > Hi Nathan, > > Thanks for reporting this. Patch below. > > @paulmck: Please also take a look below. > > On 2022-12-01, Nathan Chancellor <nathan@kernel.org> wrote: > > bad: scheduling from the idle thread! > > CPU: 0 PID: 0 Comm: swapper Not tainted 6.1.0-rc1+ #1 > > Hardware name: PowerMac3,1 7400 0xc0209 PowerMac > > Call Trace: > > [c0bc1db0] [c07f07e0] dump_stack_lvl+0x34/0x50 (unreliable) > > [c0bc1dd0] [c008429c] dequeue_task_idle+0x34/0x5c > > [c0bc1df0] [c0820924] __schedule+0x56c/0x5c4 > > [c0bc1e40] [c08209d0] schedule+0x54/0xfc > > [c0bc1e60] [c0826034] schedule_timeout+0x13c/0x194 > > [c0bc1ea0] [c082134c] __wait_for_common+0xcc/0x1f4 > > [c0bc1ee0] [c00ac8ac] synchronize_srcu+0xc8/0x12c > > [c0bc1f20] [c00a0230] unregister_console+0xc8/0x10c > > [c0bc1f40] [c009e314] register_console+0x2f4/0x390 > > [c0bc1f60] [c0a17510] pmz_console_init+0x34/0x48 > > [c0bc1f70] [c0a0491c] console_init+0x9c/0xf0 > > [c0bc1fa0] [c09f5584] start_kernel+0x588/0x6ac > > [c0bc1ff0] [00003540] 0x3540 > > This config is using TINY_RCU. Its srcu_synchronize() implementation > does not check if it called before scheduling is ready. The following > patch will fix it. > > @paulmck: Should it check (system_state < SYSTEM_SCHEDULING) instead > since TINY_RCU does not use @rcu_scheduler_active?
Thank you for chasing this down, John!
You are exactly right, and I therefore need to pull this into the pile for the upcoming merge window:
dbc6ca150842 ("srcu: Make Tiny synchronize_srcu() check for readers")
And kudos to Zqiang for a proactive fix! ;-)
I will add your (John's) Tested-by, but please let me know if this is inappropriate.
Thanx, Paul
> John Ogness > > diff --git a/kernel/rcu/srcutiny.c b/kernel/rcu/srcutiny.c > index 33adafdad261..35338e6e37e7 100644 > --- a/kernel/rcu/srcutiny.c > +++ b/kernel/rcu/srcutiny.c > @@ -197,6 +197,9 @@ void synchronize_srcu(struct srcu_struct *ssp) > { > struct rcu_synchronize rs; > > + if (rcu_scheduler_active == RCU_SCHEDULER_INACTIVE) > + return; > + > init_rcu_head_on_stack(&rs.head); > init_completion(&rs.completion); > call_srcu(ssp, &rs.head, wakeme_after_rcu);
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