linux-kernel - Re: [PATCH] Fix resume on x86-32 machines

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Message-ID: <5321270.nZsYpZjJZb@aspire.rjw.lan>
Date:   Mon, 11 Dec 2017 15:43:28 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Andrew Lutomirski <luto@...nel.org>
Cc:     Pavel Machek <pavel@....cz>, Andy Lutomirski <luto@...capital.net>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        the arch/x86 maintainers <x86@...nel.org>
Subject: Re: [PATCH] Fix resume on x86-32 machines

On Monday, December 11, 2017 3:22:39 PM CET Rafael J. Wysocki wrote:
> On Sunday, December 10, 2017 10:58:23 PM CET Andy Lutomirski wrote:
> > 
> > > On Dec 10, 2017, at 1:38 PM, Pavel Machek <pavel@....cz> wrote:
> > > 
> > > 
> > > After 4.15-rc2, suspend stopped working on Thinkpad X60. 5b06bbc
> > > (unintentionally?) reordered stuff with respect to
> > > fix_processor_context() on 32-bit and 64-bit. We undo that change on
> > > 32-bit.
> > > 
> > 
> > Can you explain what was wrong with the reordering?  Your patch certainly *looks* incorrect.
> > 
> > I'm guessing that the real issue is that 32-bit needs %fs restored early for TLS.
> 
> I *think* you are right.

Hmm.  Don't we need to restore GS on 32-bit before doing the per_cpu() thing
in fix_processor_context()?