linux-kernel - Re: powerpc/perf: add missing put_cpu_var in power_pmu_event

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Message-Id: <20150325052509.C995F1400F1@ozlabs.org>
Date:	Wed, 25 Mar 2015 16:25:09 +1100 (AEDT)
From:	Michael Ellerman <mpe@...erman.id.au>
To:	Jan Stancek <jstancek@...hat.com>, linuxppc-dev@...ts.ozlabs.org
Cc:	linux-kernel@...r.kernel.org, paulus@...ba.org, anton@...ba.org,
	tj@...nel.org, cl@...ux.com, jolsa@...hat.com, jstancek@...hat.com,
	joel@....id.au
Subject: Re: powerpc/perf: add missing put_cpu_var in power_pmu_event_init

On Tue, 2015-24-03 at 12:33:22 UTC, Jan Stancek wrote:
> One path in power_pmu_event_init() calls get_cpu_var(), but is
> missing matching call to put_cpu_var(), which causes preemption
> imbalance and crash in user-space:
> 
>   Page fault in user mode with in_atomic() = 1 mm = c000001fefa5a280
>   NIP = 3fff9bf2cae0  MSR = 900000014280f032
>   Oops: Weird page fault, sig: 11 [#23]

<snip>

Thanks. But I don't see this. I guess you have CONFIG_PREEMPT enabled?

cheers
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