This is a note to let you know that I've just added the patch titled
powerpc/perf/imc: Fix nest-imc cpuhotplug callback failure
to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: powerpc-perf-imc-fix-nest-imc-cpuhotplug-callback-failure.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Fri Feb 23 11:45:09 CET 2018
From: Anju T Sudhakar anju@linux.vnet.ibm.com Date: Tue, 5 Dec 2017 11:00:38 +0530 Subject: powerpc/perf/imc: Fix nest-imc cpuhotplug callback failure
From: Anju T Sudhakar anju@linux.vnet.ibm.com
[ Upstream commit ad2b6e01024ef23bddc3ce0bcb115ecd8c520b7e ]
Oops is observed during boot:
Faulting instruction address: 0xc000000000248340 cpu 0x0: Vector: 380 (Data Access Out of Range) at [c000000ff66fb850] pc: c000000000248340: event_function_call+0x50/0x1f0 lr: c00000000024878c: perf_remove_from_context+0x3c/0x100 sp: c000000ff66fbad0 msr: 9000000000009033 dar: 7d20e2a6f92d03c0 pid = 14, comm = cpuhp/0
While registering the cpuhotplug callbacks for nest-imc, if we fail in the cpuhotplug online path for any random node in a multi node system (because the opal call to stop nest-imc counters fails for that node), ppc_nest_imc_cpu_offline() will get invoked for other nodes who successfully returned from cpuhotplug online path.
This call trace is generated since in the ppc_nest_imc_cpu_offline() path we are trying to migrate the event context, when nest-imc counters are not even initialized.
Patch to add a check to ensure that nest-imc is registered before migrating the event context.
Fixes: 885dcd709ba9 ("powerpc/perf: Add nest IMC PMU support") Signed-off-by: Anju T Sudhakar anju@linux.vnet.ibm.com Reviewed-by: Madhavan Srinivasan maddy@linux.vnet.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/perf/imc-pmu.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
--- a/arch/powerpc/perf/imc-pmu.c +++ b/arch/powerpc/perf/imc-pmu.c @@ -309,6 +309,19 @@ static int ppc_nest_imc_cpu_offline(unsi return 0;
/* + * Check whether nest_imc is registered. We could end up here if the + * cpuhotplug callback registration fails. i.e, callback invokes the + * offline path for all successfully registered nodes. At this stage, + * nest_imc pmu will not be registered and we should return here. + * + * We return with a zero since this is not an offline failure. And + * cpuhp_setup_state() returns the actual failure reason to the caller, + * which in turn will call the cleanup routine. + */ + if (!nest_pmus) + return 0; + + /* * Now that this cpu is one of the designated, * find a next cpu a) which is online and b) in same chip. */
Patches currently in stable-queue which might be from anju@linux.vnet.ibm.com are
queue-4.14/powerpc-perf-imc-fix-nest-imc-cpuhotplug-callback-failure.patch