linux-kernel - Re: 2.6.34-rc2 - crash on shutdown

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Message-ID: <bd4cb8901003231540m8930e64va042fc1caf287a3f@mail.gmail.com>
Date:	Tue, 23 Mar 2010 23:40:47 +0100
From:	Stephane Eranian <eranian@...gle.com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Clemens Ladisch <clemens@...isch.de>,
	David R <david@...olicited.net>, linux-kernel@...r.kernel.org
Subject: Re: 2.6.34-rc2 - crash on shutdown

On Tue, Mar 23, 2010 at 11:18 PM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> On Tuesday 23 March 2010, Clemens Ladisch wrote:
>> Stephane Eranian wrote:
>> > On Tue, Mar 23, 2010 at 1:02 PM, Clemens Ladisch <clemens@...isch.de> wrote:
>> > > The only pointer access in this function is cpuhw->amd_nb, but
>> > > I don't see any obvious bugs.
>> >
>> > I reported a problem with the AMD initialization just last week.
>> > There is an issue with amd_pmu_cpu_online() which gets called
>> > too early, and thus fails. That leaves some bogus state and causes
>> > a crash in amd_pmu_cpu_offline().
>> >
>> > I proposed a fix which was rejected. The alternative involves moving
>> > some the of CPU initialization code (on AMD) to an earlier position,i.e.,
>> > which would be executed before the CPU_STARTED notifier. Nobody
>> > has proposed anything else so far.
>>
>> I don't know about the early bootmem stuff, but regardless of this issue,
>> if amd_pmu_cpu_online() can fail, then amd_pmu_cpu_offline() must be able
>> to handle this without blowing up.  Something like this (untested):
>
> I guess we handle that already:
>
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=a90110c61073eab95d1986322693c2b9a8a6a5f6
>
Ok, the fix avoids the crash but perf_events support for AMD is still broken.

The root of the problem is elsewhere as I pointed out last week. Peter proposed
a patch today and I think this would be enough to avoid the crash and have
perf_events working again on AMD.
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