Messages in this thread | | | Date | Tue, 26 Jan 2021 17:23:43 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 0/2] Fix BUG: Invalid wait context in hrtimer_interrupt() |
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On Wed, Jan 27, 2021 at 12:58:33AM +0900, Sergey Senozhatsky wrote: > On (21/01/26 14:59), Qais Yousef wrote:
> > # [67628.388606] hrtimer: interrupt took 304720 ns > > [67628.393546] > > [67628.393550] ============================= > > [67628.393554] [ BUG: Invalid wait context ] > > [67628.393557] 5.11.0-rc3-00019-g86be331946f7 #37 Not tainted > > [67628.393560] ----------------------------- > > [67628.393563] sugov:0/192 is trying to lock: > > [67628.393566] ffff000800b1d898 (&port_lock_key){-.-.}-{3:3}, at: pl011_console_write+0x138/0x218 > > [67628.393581] other info that might help us debug this: > > [67628.393584] context-{2:2} > > [67628.393586] 4 locks held by sugov:0/192: > > [67628.393589] #0: ffff0008059cb720 (&sg_policy->work_lock){+.+.}-{4:4}, at: sugov_work+0x58/0x88 > > [67628.393603] #1: ffff800015446f20 (prepare_lock){+.+.}-{4:4}, at: clk_prepare_lock+0x34/0xb0 > > [67628.393618] #2: ffff8000152aaa60 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0x12c/0x310 > > [67628.393632] #3: ffff8000152aab88 (console_owner){-.-.}-{0:0}, at: console_unlock+0x190/0x6d8
> > Did I miss something? > > printk() is not permitted to sleep/schedule/etc and it never does. > Generally it should be OK to call it from IRQ (module recursion paths).
The report is that it is trying to acquire spin_lock() while holding raw_spin_lock(), which is an invalid lock nesting.
Note that this is CONFIG_PROVE_RAW_LOCK_NESTING=y which specifically checks for this.
On current (mainline) kernel configs this is not yet a problem, but the moment we do land PREEMPT_RT this order will be problematic.
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