linux-kernel - Re: TSC not updating after resume: Bug or Feature?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <b637ec0b0812211443u1ca9c11du5d61c41e3d82bc16@mail.gmail.com>
Date:	Sun, 21 Dec 2008 23:43:36 +0100
From:	"Fabio Comolli" <fabio.comolli@...il.com>
To:	"Thomas Gleixner" <tglx@...utronix.de>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, "Ingo Molnar" <mingo@...e.hu>,
	"Peter Zijlstra" <peterz@...radead.org>,
	"Steven Rostedt" <srostedt@...hat.com>, dsaxena@...xity.net,
	linux-kernel@...r.kernel.org,
	"Dave Kleikamp" <shaggy@...ux.vnet.ibm.com>
Subject: Re: TSC not updating after resume: Bug or Feature?

Hi Thomas.

On Sun, Dec 21, 2008 at 8:43 PM, Thomas Gleixner <tglx@...utronix.de> wrote:
> On Sun, 21 Dec 2008, Thomas Gleixner wrote:
>> On Thu, 18 Dec 2008, Rafael J. Wysocki wrote:
>> > >  5b7dba4: sched_clock: prevent scd->clock from moving backwards
>> > >
>> > > and the bug triggered by hibernation fixed instead.
>>
>> Hmm. Depending on the hibernation sleep time we can end up with a
>> pretty long delta between the pre suspend and the post resume call to
>> __update_sched_clock().
>>
>> I have the feeling that sched_clock looks into stale values after
>> resume and the first call to __update_sched_clock() trips over the
>> stale scd->clock value. Shaggy's patch brings scd->clock into the mix
>> and that might cause the whole machinery to blow up on resume.
>>
>> Also we need to investigate whether sched_clock is referencing gtod
>> values _before_ timekeeping is resume.
>
> I checked the two bugzillas (12149 & 12155) and both reporters have
> hpet=force on the command line.

Well, I'm the submitter of bug 12155 and I never had hpet=force on my
command line. I don't know where you found it.
Actually my command line is:

-------------------------------------------------------------------------------------------------------------------------
fcomolli@...king:~> cat /proc/cmdline
root=/dev/sda2 resume=/dev/sda3 i8042.nomux=1 pciehp.pciehp_force=1
quiet splash=silent vga=791
-------------------------------------------------------------------------------------------------------------------------

By the way, I don't know if it matters but the problema happened with
in-kernel hibernation and also in out-of-tree TuxOnIce hibernation.
Maybe this can help debugging the issue, I don't know.

>
> One of the reporters said: "If I de-select CONFIG_HPET_TIMER then the
> issue went away ..."
>
> It looks like this was not further investigated. Is this problem
> reproducible on other systems as well ?
>
> Thanks,
>
>        tglx
> --

Regards,
Fabio


> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/