Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933399AbaLBWxs (ORCPT ); Tue, 2 Dec 2014 17:53:48 -0500 Received: from mail-qa0-f42.google.com ([209.85.216.42]:49253 "EHLO mail-qa0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933086AbaLBWxr (ORCPT ); Tue, 2 Dec 2014 17:53:47 -0500 Message-ID: <547E42F7.5070105@gmail.com> Date: Tue, 02 Dec 2014 17:53:43 -0500 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Peter Zijlstra , Ingo Molnar CC: LKML , Dave Jones , Andrey Ryabinin Subject: sched: odd values for effective load calculations Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi all, I was fuzzing with trinity inside a KVM tools guest, running the latest -next kernel along with the undefined behaviour sanitizer patch, and hit the following: [ 787.894288] ================================================================================ [ 787.897074] UBSan: Undefined behaviour in kernel/sched/fair.c:4541:17 [ 787.898981] signed integer overflow: [ 787.900066] 361516561629678 * 101500 cannot be represented in type 'long long int' [ 787.900066] CPU: 18 PID: 12958 Comm: trinity-c103 Not tainted 3.18.0-rc6-next-20141201-sasha-00070-g028060a-dirty #1528 [ 787.900066] 0000000000000000 0000000000000000 ffffffff93b0f890 ffff8806e3eff918 [ 787.900066] ffffffff91f1cf26 1ffffffff3c2de73 ffffffff93b0f8a8 ffff8806e3eff938 [ 787.900066] ffffffff91f1fb90 1ffffffff3c2de73 ffffffff93b0f8a8 ffff8806e3eff9f8 [ 787.900066] Call Trace: [ 787.900066] dump_stack (lib/dump_stack.c:52) [ 787.900066] ubsan_epilogue (lib/ubsan.c:159) [ 787.900066] handle_overflow (lib/ubsan.c:191) [ 787.900066] ? __do_page_fault (arch/x86/mm/fault.c:1220) [ 787.900066] ? local_clock (kernel/sched/clock.c:392) [ 787.900066] __ubsan_handle_mul_overflow (lib/ubsan.c:218) [ 787.900066] select_task_rq_fair (kernel/sched/fair.c:4541 kernel/sched/fair.c:4755) [ 787.900066] try_to_wake_up (kernel/sched/core.c:1415 kernel/sched/core.c:1724) [ 787.900066] ? trace_hardirqs_on_thunk (arch/x86/lib/thunk_64.S:33) [ 787.900066] default_wake_function (kernel/sched/core.c:2979) [ 787.900066] ? get_parent_ip (kernel/sched/core.c:2559) [ 787.900066] autoremove_wake_function (kernel/sched/wait.c:295) [ 787.900066] ? get_parent_ip (kernel/sched/core.c:2559) [ 787.900066] __wake_up_common (kernel/sched/wait.c:73) [ 787.900066] __wake_up_sync_key (include/linux/spinlock.h:364 kernel/sched/wait.c:146) [ 787.900066] pipe_write (fs/pipe.c:466) [ 787.900066] ? kasan_poison_shadow (mm/kasan/kasan.c:48) [ 787.900066] ? new_sync_read (fs/read_write.c:480) [ 787.900066] do_iter_readv_writev (fs/read_write.c:681) [ 787.900066] compat_do_readv_writev (fs/read_write.c:1029) [ 787.900066] ? wait_for_partner (fs/pipe.c:340) [ 787.900066] ? _raw_spin_unlock (./arch/x86/include/asm/preempt.h:95 include/linux/spinlock_api_smp.h:152 kernel/locking/spinlock.c:183) [ 787.900066] ? __this_cpu_preempt_check (lib/smp_processor_id.c:63) [ 787.900066] ? syscall_trace_enter_phase1 (include/linux/context_tracking.h:27 arch/x86/kernel/ptrace.c:1486) [ 787.900066] compat_writev (fs/read_write.c:1145) [ 787.900066] compat_SyS_writev (fs/read_write.c:1163 fs/read_write.c:1151) [ 787.900066] ia32_do_call (arch/x86/ia32/ia32entry.S:446) [ 787.900066] ================================================================================ The values for effective load seem a bit off (and are overflowing!). One change I did recently was to disable lock debugging, could it be related? Thanks, Sasha -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/