Re: [PATCH] x86/entry/64: Fix native_load_gs_index() SWAPGS handling with IRQ state tracing enabled

From: Thomas Gleixner <tglx@linutronix.de>
To: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH] x86/entry/64: Fix native_load_gs_index() SWAPGS handling with IRQ state tracing enabled
Date: Wed, 29 Nov 2017 10:28:30 +0100 (CET)	[thread overview]
Message-ID: <alpine.DEB.2.20.1711291027450.1825@nanos> (raw)
In-Reply-To: <17b6e0c8-db18-f63d-0118-52b85c0c2a7f@linux.intel.com>

On Wed, 29 Nov 2017, Jarkko Nikula wrote:

> On 11/29/2017 09:09 AM, Ingo Molnar wrote:
> > 
> > * Jarkko Nikula <jarkko.nikula@linux.intel.com> wrote:
> > 
> > > Hi
> > > 
> > > Suspend-to-ram and resume stopped working on v4.15-rc1 and I bisected it
> > > to commit ca37e57bbe0c ("x86/entry/64: Add missing irqflags tracing to
> > > native_load_gs_index()").
> > > 
> > > I noticed it on Intel Kabylake (core) and Apollolake (atom) based
> > > prototype machines. Symptoms are that machine appears to enter
> > > into suspend but resumes instantly and hangs. Unfortunately no
> > > logs.
> > > 
> > > If I revert ca37e57bbe0c on v4.15-rc1 it works as expected.
> > 
> > Hm, that commit looks broken with irq-tracing enabled. Does the
> > patch below fix it?
> > 
> No, it makes the machine not to boot at all :-(
> 
> Log below when I used my config (now attached). With x86_64_defconfig it
> booted twice but didn't survive suspend/resume. However several other boot
> attempts with x86_64_defconfig failed somewhat similarly. Not in the same
> place but hanging anyway. With my own config it seems to always end up failing
> in trace_hardirqs_off_caller.

Does it work when you disable all the tracing muck?

Thanks,

	tglx