From 7d42896628202a551ad1107697cd215dc5fca099 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 23 Sep 2009 11:03:37 +0200 Subject: [PATCH] perf_event, x86: Fix 'perf sched record' crashing the machine Chris Malley reported that 'perf sched record' sometimes crashes his box with: [ 389.272175] BUG: unable to handle kernel paging request at ffffb300 [ 389.272294] IP: [] default_send_IPI_self+0x1d/0x50 [ 389.272366] *pde = 0073f067 *pte = 00000000 [ 389.274708] Call Trace: [ 389.274752] [] ? set_perf_event_pending+0x14/0x20 [ 389.274801] [] ? perf_output_unlock+0x121/0x1a0 [ 389.274848] [] ? perf_output_end+0x4a/0x70 [ 389.274893] [] ? __perf_event_overflow+0x240/0x2f0 [ 389.274942] [] ? atomic64_cmpxchg+0x1e/0x30 [ 389.274988] [] ? perf_swevent_ctx_event+0x1b4/0x1c0 [ 389.275035] [] ? perf_swevent_ctx_event+0x33/0x1c0 [ 389.275081] [] ? do_perf_sw_event+0xa7/0x160 [ 389.275127] [] ? perf_tp_event+0x82/0xa0 [ 389.275174] [] ? ftrace_profile_sched_stat_runtime+0xe6/0x120 [ 389.275224] [] ? ftrace_profile_sched_stat_runtime+0x0/0x120 [ 389.275273] [] ? update_curr+0x18a/0x230 [ 389.275318] [] ? put_prev_task_fair+0x155/0x160 [ 389.275366] [] ? sched_clock_cpu+0xd5/0x110 [ 389.275413] [] ? _spin_lock_irq+0x45/0x50 [ 389.275458] [] ? schedule+0x20e/0xb10 The problem is that the box has no lapic enabled: [ 0.042445] Local APIC not detected. Using dummy APIC emulation. The below seems like the best fix. We disabled all lapic bits, except the self-IPI-resend logic. Reported-by: Chris Malley Signed-off-by: Peter Zijlstra Cc: Cyrill Gorcunov Cc: Frederic Weisbecker LKML-Reference: <7863dc4c0909221409v7893bfd3o4b590d5951a233ba@mail.gmail.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/perf_event.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index a3c7adb06b78..b5801c311846 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -1790,6 +1790,9 @@ void smp_perf_pending_interrupt(struct pt_regs *regs) void set_perf_event_pending(void) { #ifdef CONFIG_X86_LOCAL_APIC + if (!x86_pmu.apic || !x86_pmu_initialized()) + return; + apic->send_IPI_self(LOCAL_PENDING_VECTOR); #endif } -- 2.20.1