From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v3 01/22] hardirq/nmi: Allow nested nmi_enter() Date: Wed, 19 Feb 2020 18:07:25 +0100 Message-ID: <20200219170725.GO18400@hirez.programming.kicks-ass.net> References: <20200219144724.800607165@infradead.org> <20200219150744.428764577@infradead.org> <20200219103126.33f67cf3@gandalf.local.home> <20200219165650.GB32346@zn.tnic> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from bombadil.infradead.org ([198.137.202.133]:37136 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726598AbgBSRHy (ORCPT ); Wed, 19 Feb 2020 12:07:54 -0500 Content-Disposition: inline In-Reply-To: <20200219165650.GB32346@zn.tnic> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Borislav Petkov Cc: Steven Rostedt , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, mingo@kernel.org, joel@joelfernandes.org, gregkh@linuxfoundation.org, gustavo@embeddedor.com, tglx@linutronix.de, paulmck@kernel.org, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, luto@kernel.org, tony.luck@intel.com, frederic@kernel.org, dan.carpenter@oracle.com, mhiramat@kernel.org, Will Deacon , Marc Zyngier , Michael Ellerman , Petr Mladek On Wed, Feb 19, 2020 at 05:56:50PM +0100, Borislav Petkov wrote: > On Wed, Feb 19, 2020 at 10:31:26AM -0500, Steven Rostedt wrote: > > Probably should document somewhere (in a comment above nmi_enter()?) > > that we allow nmi_enter() to nest up to 15 times. > > Yah, and can we make the BUG_ON() WARN_ON or so instead, so that there's > at least a chance to be able to catch it for debugging. Or is the box > going to be irreparably wedged after the 4 bits overflow? It's going to be fairly buggered, because at that point in_nmi() is going to be false again. It might survive for a little, it might not.