linux-kernel - Re: 174cc7187e6f ACPICA: Tables: Back port acpi_get_table_with_size() and early_acpi_os_unmap

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Date:   Wed, 11 Jan 2017 11:03:23 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:     "Zheng, Lv" <lv.zheng@...el.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        "Moore, Robert" <robert.moore@...el.com>,
        J?rg R?del <joro@...tes.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Linux ACPI <linux-acpi@...r.kernel.org>
Subject: Re: 174cc7187e6f ACPICA: Tables: Back port
 acpi_get_table_with_size() and early_acpi_os_unmap_memory() from Linux
 kernel

On Wed, Jan 11, 2017 at 01:51:56AM -0800, Paul E. McKenney wrote:
> Yes, you could make RCU expedited grace periods go back to using the
> requesting task, and that would allow expedited grace periods to run early
> in the boot process.  But that causes problems with signals and the like
> unless you revert a few other patches.  The bugzilla is interesting --
> it looks like ACPI was in some cases doing early-boot grace-period waits
> some time back?

I think this and https://bugzilla.suse.com/show_bug.cgi?id=1017783 is an
example of a bunch of toshiba schlaptops which cause the issue. So it
looks like ACPI is doing something very early on those which tickles the
issue to happen.

But this is ACPI - anything can happen!

> I have a limping prototype RCU patch that should avoid this problem.
>
> If all goes well, I will send it out late tomorrow evening, Pacific Time.

Attach it to the bugzilla too, pls, because the people there trigger the
issue.

I have the respective(?) SUSE bug and I can ask people there to run it
too.

Thanks.

-- 
Regards/Gruss,
    Boris.

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