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To: Mahesh J Salgaonkar <mahesh@linux.vnet.ibm.com>,
 linuxppc-dev <linuxppc-dev@ozlabs.org>
From: Michael Ellerman <patch-notifications@ellerman.id.au>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: Re: powernv: Avoid calling trace tlbie in kexec path.
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Date: Fri, 24 Nov 2017 20:46:40 +1100 (AEDT)
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On Wed, 2017-11-22 at 17:32:07 UTC, Mahesh J Salgaonkar wrote:
> From: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
> 
> Rebooting into a new kernel with kexec fails in trace_tlbie() which is
> called from native_hpte_clear(). This happens if the running kernel has
> CONFIG_LOCKDEP enabled. With lockdep enabled, the tracepoints always
> execute few RCU checks regardless of whether tracing is on or off.
> We are already in the last phase of kexec sequence in real mode with
> HILE_BE set. At this point the RCU check ends up in RCU_LOCKDEP_WARN and
> causes kexec to fail.
> 
> Fix this by not calling trace_tlbie() from native_hpte_clear().
> 
> Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
> Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/a3961f824cdbe7eb431254dc7d8f6f

cheers