From: Peter Zijlstra <peterz@infradead.org>
To: John Ogness <john.ogness@linutronix.de>
Cc: Qais Yousef <qais.yousef@arm.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Petr Mladek <pmladek@suse.com>,
Thomas Gleixner <tglx@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/2] Fix BUG: Invalid wait context in hrtimer_interrupt()
Date: Tue, 26 Jan 2021 17:18:59 +0100 [thread overview]
Message-ID: <YBBA81osV7cHN2fb@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <874kj3lo3h.fsf@jogness.linutronix.de>
On Tue, Jan 26, 2021 at 04:28:42PM +0106, John Ogness wrote:
> On 2021-01-26, Qais Yousef <qais.yousef@arm.com> wrote:
> > [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
> pl011_console_write() does:
>
> local_irq_save(flags);
> spin_lock(&uap->port.lock);
>
> This needs to be:
>
> spin_lock_irqsave(&uap->port.lock, flags);
>
> Of course, it will be a trickier than that because of the
> @oops_in_progress madness. This bug has been around for quite a while.
Well yes, but that's not going to be fixing anything.
The problem is that sugov_work() is holding a raw_spin_lock, and you're
trying to acquire a spin_lock.
That's an invalid lock nesting.
next prev parent reply other threads:[~2021-01-26 16:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-23 23:37 Qais Yousef
2021-01-23 23:37 ` [PATCH 1/2] printk: Add new pr_*_deferred_once() variants Qais Yousef
2021-01-25 10:37 ` Peter Zijlstra
2021-01-25 10:58 ` John Ogness
2021-01-25 19:46 ` Qais Yousef
2022-01-11 13:40 ` Andy Shevchenko
2022-01-13 11:20 ` Qais Yousef
2021-01-23 23:37 ` [PATCH 2/2] hrtimer: Use pr_warn_deferred_once() in hrtimer_interrupt() Qais Yousef
2021-01-26 4:46 ` [PATCH 0/2] Fix BUG: Invalid wait context " Sergey Senozhatsky
2021-01-26 14:59 ` Qais Yousef
2021-01-26 15:22 ` John Ogness
2021-01-26 16:18 ` Peter Zijlstra [this message]
2021-01-26 15:58 ` Sergey Senozhatsky
2021-01-26 16:23 ` Peter Zijlstra
2021-01-26 18:08 ` Qais Yousef
2021-01-26 16:58 ` Petr Mladek
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