linux-kernel - Re: [PATCH] powerpc/perf: Fix ref-counting on the PMU 'vpa

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Message-ID: <174192385436.14370.8988935499499753559.b4-ty@linux.ibm.com>
Date: Fri, 14 Mar 2025 09:17:02 +0530
From: Madhavan Srinivasan <maddy@...ux.ibm.com>
To: linuxppc-dev@...ts.ozlabs.org, kvm-ppc@...r.kernel.org,
        linux-kernel@...r.kernel.org, Vaibhav Jain <vaibhav@...ux.ibm.com>
Cc: Michael Ellerman <mpe@...erman.id.au>, atrajeev@...ux.vnet.ibm.com,
        kjain@...ux.ibm.com, disgoel@...ux.ibm.com, hbathini@...ux.ibm.com,
        adubey@...ux.ibm.com, gautam@...ux.ibm.com
Subject: Re: [PATCH] powerpc/perf: Fix ref-counting on the PMU 'vpa_pmu'

On Tue, 04 Feb 2025 21:05:26 +0530, Vaibhav Jain wrote:
> Commit 176cda0619b6 ("powerpc/perf: Add perf interface to expose vpa
> counters") introduced 'vpa_pmu' to expose Book3s-HV nested APIv2 provided
> L1<->L2 context switch latency counters to L1 user-space via
> perf-events. However the newly introduced PMU named 'vpa_pmu' doesn't
> assign ownership of the PMU to the module 'vpa_pmu'. Consequently the
> module 'vpa_pmu' can be unloaded while one of the perf-events are still
> active, which can lead to kernel oops and panic of the form below on a
> Pseries-LPAR:
> 
> [...]

Applied to powerpc/next.

[1/1] powerpc/perf: Fix ref-counting on the PMU 'vpa_pmu'
      https://git.kernel.org/powerpc/c/ff99d5b6a246715f2257123cdf6c4a29cb33aa78

Thanks