Messages in this thread | | | Date | Tue, 6 Sep 2016 10:13:23 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] perf/x86/intel/cqm: Check cqm/mbm enabled state in event init |
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On Mon, Sep 05, 2016 at 05:30:07PM +0200, Jiri Olsa wrote: > Yanqiu Zhang reported kernel panic when using mbm event > on system where CQM is detected but without mbm event > support, like with perf: > > # perf stat -e 'intel_cqm/event=3/' -a > > BUG: unable to handle kernel NULL pointer dereference at 0000000000000020 > IP: [<ffffffff8100d64c>] update_sample+0xbc/0xe0 > ... > <IRQ> > [<ffffffff8100d688>] __intel_mbm_event_init+0x18/0x20 > [<ffffffff81113d6b>] flush_smp_call_function_queue+0x7b/0x160 > [<ffffffff81114853>] generic_smp_call_function_single_interrupt+0x13/0x60 > [<ffffffff81052017>] smp_call_function_interrupt+0x27/0x40 > [<ffffffff816fb06c>] call_function_interrupt+0x8c/0xa0 > ... > > The reason is that we currently allow to init mbm event > even if mbm support is not detected. Adding checks for > both cqm and mbm events and support into cqm's event_init. > > Reported-by: Yanqiu Zhang <yanqzhan@redhat.com> > Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Fixes: 33c3cc7acfd9 ("perf/x86/mbm: Add Intel Memory B/W Monitoring enumeration and init")
Cc: stable@vger.kernelo.org # 4.6+
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