From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E434614C59B for ; Thu, 22 Feb 2024 15:17:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708615044; cv=none; b=QcOrM2tWdJ8cQlxWoZofTyDEOSQv3gUdpipYI9AjZrqHeu2FINvQmB3RrfJ6pjqTQ4g0GX8pWoo20s+imlEgBr8JpZj5u0ryZVrOGTAHRrQa0ojQmx/+okp/KKdAqKPZniTw2nlAloczP18B+XDK97MsgfokBRG+Tmir5veuHq8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708615044; c=relaxed/simple; bh=rNZr/qFbvQHD7VbWILK52ET8FPFhOj9+F1CVqYpT9f0=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=DyCNJXQThFRg3KfScPhWFAvMZa0XZ+Vuxvcp9bmrPWefeYIuT77Nj2Gc2DTK/4zgifjjdsb2rsgnHS7jOMzMNhdgy6PdoN8RyV1LAuSAxZc1+WZl6uT/9DNbpe4Hnm5d2l+GbW42OUrLWP6ZJLDpBYcUliDs+vabIHI0VPwHmX0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=AtRvhUD2; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=2ZFYFNdm; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="AtRvhUD2"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="2ZFYFNdm" From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1708615041; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=JqXgMEODvPqPWYehMT24n8azEjHEKTzJ7cm4bihqX5A=; b=AtRvhUD2TcijhmJTc2X2hbKB5Qiw5lbsMzLyZSv3kYjk6+Ek+7o0Rhd3/c391N+BwFtmeP OgXY4RiLCjegmvreLavnTKvPx5Ftre63el61eNLf0Z/pRdCcJtGp1LO73ypE7uBSq0vbTF r4XOAL9AN/zgAkaaAWhSKHbmrnybcqlEjNRL9784LpmM27NnHPpyoHcRl263XT9Rsuc1ZB p/Pl+cU0UZL6h+7L29nadqdDEeoGWCbHl4cYAHhiubfdNAZ+MvQvBA59WwIPPe0T9kZoZ+ QaJfDH6dzH1+Rk480UNdoDKy6XAo+Xfg21jttdh/AlIAFFRvnoM2UDbu8bun9g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1708615041; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=JqXgMEODvPqPWYehMT24n8azEjHEKTzJ7cm4bihqX5A=; b=2ZFYFNdmrBhxKjlPD+VSEjVhYQRF7PKVsIHqOr4x3DFyvOAhNySXWUnlmIk5zOcj7LW8Ee AfiaE5DBj/sUTODw== To: John Stultz , LKML Cc: John Stultz , Frederic Weisbecker , Steven Rostedt , kernel-team@android.com, John Ogness Subject: Re: [RFC][PATCH] hrtimer: Use printk_deferred_once for hrtimer_interrupt message In-Reply-To: <20240222051253.1361002-1-jstultz@google.com> References: <20240222051253.1361002-1-jstultz@google.com> Date: Thu, 22 Feb 2024 16:17:20 +0100 Message-ID: <8734tkfrzz.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Wed, Feb 21 2024 at 21:12, John Stultz wrote: Cc+ John. Keeping context intact, > With qemu, I constantly see lockdep warnings after the > hrimter_interrupt message is printed: > > [ 43.434557] hrtimer: interrupt took 6517564 ns > [ 43.435000] > [ 43.435000] ============================= > [ 43.435000] [ BUG: Invalid wait context ] Do you have PROVE_RAW_LOCK_NESTING enabled? > [ 43.435000] 6.8.0-rc5-00002-g28763ef29a5b #3743 Not tainted > [ 43.435000] ----------------------------- > [ 43.435000] lock_torture_wr/605 is trying to lock: > [ 43.435000] ffffffffbdcdc6f8 (&port_lock_key){-...}-{3:3}, at: serial8250_console_write+0xdd/0x710 > [ 43.435000] other info that might help us debug this: > [ 43.435000] context-{2:2} > [ 43.435000] 4 locks held by lock_torture_wr/605: > [ 43.435000] #0: ffffffffbd6f1de8 (torture_mutex_init#4){+.+.}-{4:4}, at: torture_mutex_nested_lock+0x4b/0x70 > [ 43.435000] #1: ffffffffbb557260 (console_lock){+.+.}-{0:0}, at: vprintk_emit+0xd3/0x330 > [ 43.435000] #2: ffffffffbb5572d0 (console_srcu){....}-{0:0}, at: console_flush_all+0xd6/0x6b0 > [ 43.435000] #3: ffffffffbb396e20 (console_owner){-...}-{0:0}, at: console_flush_all+0x2a0/0x6b0 > [ 43.435000] stack backtrace: > [ 43.435000] CPU: 36 PID: 605 Comm: lock_torture_wr Not tainted 6.8.0-rc5-00002-g28763ef29a5b #3743 > [ 43.435000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 > [ 43.435000] Call Trace: > [ 43.435000] > [ 43.435000] dump_stack_lvl+0x57/0x90 > [ 43.435000] __lock_acquire+0xd07/0x3260 > [ 43.435000] ? __pfx___lock_acquire+0x10/0x10 > [ 43.435000] ? memchr+0x1e/0x50 > [ 43.435000] lock_acquire+0x159/0x3b0 > [ 43.435000] ? serial8250_console_write+0xdd/0x710 > [ 43.435000] ? __pfx_lock_acquire+0x10/0x10 > [ 43.435000] ? __pfx___lock_acquire+0x10/0x10 > [ 43.435000] _raw_spin_lock_irqsave+0x42/0x60 > [ 43.435000] ? serial8250_console_write+0xdd/0x710 > [ 43.435000] serial8250_console_write+0xdd/0x710 > [ 43.435000] ? __pfx_serial8250_console_write+0x10/0x10 > [ 43.435000] ? __pfx_lock_release+0x10/0x10 > [ 43.435000] ? do_raw_spin_lock+0x104/0x180 > [ 43.435000] ? __pfx_do_raw_spin_lock+0x10/0x10 > [ 43.435000] ? console_flush_all+0x2a0/0x6b0 > [ 43.435000] console_flush_all+0x2ea/0x6b0 > [ 43.435000] ? console_flush_all+0x2a0/0x6b0 > [ 43.435000] ? __pfx_console_flush_all+0x10/0x10 > [ 43.435000] ? __pfx_lock_acquire+0x10/0x10 > [ 43.435000] console_unlock+0x9d/0x150 > [ 43.435000] ? __pfx_console_unlock+0x10/0x10 > [ 43.435000] ? vprintk_emit+0xd3/0x330 > [ 43.435000] ? __down_trylock_console_sem+0x62/0xa0 > [ 43.435000] ? vprintk_emit+0xd3/0x330 > [ 43.435000] vprintk_emit+0xdc/0x330 > [ 43.435000] _printk+0x92/0xb0 > [ 43.435000] ? __pfx__printk+0x10/0x10 > [ 43.435000] ? hrtimer_interrupt+0x2f0/0x360 > [ 43.439262] __sysvec_apic_timer_interrupt+0xb8/0x290 > [ 43.439345] sysvec_apic_timer_interrupt+0x8a/0xb0 > [ 43.439345] > [ 43.439345] > [ 43.439345] asm_sysvec_apic_timer_interrupt+0x16/0x20 > > I thought the new printk work was going to resolve this, but > apparently not, so to avoid trying to printk in this problematic > context, lets use prink_deferred_once() instead. > > Cc: Thomas Gleixner > Cc: Frederic Weisbecker > Cc: Steven Rostedt > Cc: kernel-team@android.com > Signed-off-by: John Stultz > --- > kernel/time/hrtimer.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c > index edb0f821dcea..e6b060403384 100644 > --- a/kernel/time/hrtimer.c > +++ b/kernel/time/hrtimer.c > @@ -1870,7 +1870,8 @@ void hrtimer_interrupt(struct clock_event_device *dev) > else > expires_next = ktime_add(now, delta); > tick_program_event(expires_next, 1); > - pr_warn_once("hrtimer: interrupt took %llu ns\n", ktime_to_ns(delta)); > + printk_deferred_once(KERN_WARNING "hrtimer: interrupt took %llu ns\n", > + ktime_to_ns(delta)); > } > > /* called with interrupts disabled */