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Message-ID: <53AAFFE3.3020205@linux.vnet.ibm.com> Date: Wed, 25 Jun 2014 22:29:15 +0530 From: "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com> To: Sasha Levin <sasha.levin@...cle.com> CC: peterz@...radead.org, tglx@...utronix.de, mingo@...nel.org, tj@...nel.org, rusty@...tcorp.com.au, akpm@...ux-foundation.org, fweisbec@...il.com, hch@...radead.org, mgorman@...e.de, riel@...hat.com, bp@...e.de, rostedt@...dmis.org, mgalbraith@...e.de, ego@...ux.vnet.ibm.com, paulmck@...ux.vnet.ibm.com, oleg@...hat.com, rjw@...ysocki.net, linux-kernel@...r.kernel.org, Dave Jones <davej@...hat.com> Subject: Re: [PATCH v7 2/2] CPU hotplug, smp: Flush any pending IPI callbacks before CPU offline On 06/25/2014 09:12 PM, Sasha Levin wrote: > On 05/26/2014 07:08 AM, Srivatsa S. Bhat wrote: >> During CPU offline, in stop-machine, we don't enforce any rule in the >> _DISABLE_IRQ stage, regarding the order in which the outgoing CPU and the other >> CPUs disable their local interrupts. Hence, we can encounter a scenario as >> depicted below, in which IPIs are sent by the other CPUs to the CPU going >> offline (while it is *still* online), but the outgoing CPU notices them only >> *after* it has gone offline. >> [...] > Hi all, > > While fuzzing with trinity inside a KVM tools guest running the latest -next > kernel I've stumbled on the following spew: > Thanks for the bug report. Please test if this patch fixes the problem for you: https://git.kernel.org/cgit/linux/kernel/git/peterz/queue.git/commit/?h=timers/nohz&id=921d8b81281ecdca686369f52165d04fa3505bd7 Regards, Srivatsa S. Bhat > [ 1982.600053] kernel BUG at kernel/irq_work.c:175! > [ 1982.600053] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC > [ 1982.600053] Dumping ftrace buffer: > [ 1982.600053] (ftrace buffer empty) > [ 1982.600053] Modules linked in: > [ 1982.600053] CPU: 14 PID: 168 Comm: migration/14 Not tainted 3.16.0-rc2-next-20140624-sasha-00024-g332b58d #726 > [ 1982.600053] task: ffff88036a5a3000 ti: ffff88036a5ac000 task.ti: ffff88036a5ac000 > [ 1982.600053] RIP: irq_work_run (kernel/irq_work.c:175 (discriminator 1)) > [ 1982.600053] RSP: 0000:ffff88036a5afbe0 EFLAGS: 00010046 > [ 1982.600053] RAX: 0000000080000001 RBX: 0000000000000000 RCX: 0000000000000008 > [ 1982.600053] RDX: 000000000000000e RSI: ffffffffaf9185fb RDI: 0000000000000000 > [ 1982.600053] RBP: ffff88036a5afc08 R08: 0000000000099224 R09: 0000000000000000 > [ 1982.600053] R10: 0000000000000000 R11: 0000000000000001 R12: ffff88036afd8400 > [ 1982.600053] R13: 0000000000000000 R14: ffffffffb0cf8120 R15: ffffffffb0cce5d0 > [ 1982.600053] FS: 0000000000000000(0000) GS:ffff88036ae00000(0000) knlGS:0000000000000000 > [ 1982.600053] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > [ 1982.600053] CR2: 00000000019485d0 CR3: 00000002c7c8f000 CR4: 00000000000006a0 > [ 1982.600053] Stack: > [ 1982.600053] ffffffffab20fbb5 0000000000000082 ffff88036afd8440 0000000000000000 > [ 1982.600053] 0000000000000001 ffff88036a5afc28 ffffffffab20fca7 0000000000000000 > [ 1982.600053] 00000000ffffffef ffff88036a5afc78 ffffffffab19c58e 000000000000000e > [ 1982.600053] Call Trace: > [ 1982.600053] ? flush_smp_call_function_queue (kernel/smp.c:263) > [ 1982.600053] hotplug_cfd (kernel/smp.c:81) > [ 1982.600053] notifier_call_chain (kernel/notifier.c:95) > [ 1982.600053] __raw_notifier_call_chain (kernel/notifier.c:395) > [ 1982.600053] __cpu_notify (kernel/cpu.c:202) > [ 1982.600053] cpu_notify (kernel/cpu.c:211) > [ 1982.600053] take_cpu_down (./arch/x86/include/asm/current.h:14 kernel/cpu.c:312) > [ 1982.600053] multi_cpu_stop (kernel/stop_machine.c:201) > [ 1982.600053] ? __stop_cpus (kernel/stop_machine.c:170) > [ 1982.600053] cpu_stopper_thread (kernel/stop_machine.c:474) > [ 1982.600053] ? put_lock_stats.isra.12 (./arch/x86/include/asm/preempt.h:98 kernel/locking/lockdep.c:254) > [ 1982.600053] ? _raw_spin_unlock_irqrestore (./arch/x86/include/asm/paravirt.h:809 include/linux/spinlock_api_smp.h:160 kernel/locking/spinlock.c:191) > [ 1982.600053] ? __this_cpu_preempt_check (lib/smp_processor_id.c:63) > [ 1982.600053] ? trace_hardirqs_on_caller (kernel/locking/lockdep.c:2557 kernel/locking/lockdep.c:2599) > [ 1982.600053] smpboot_thread_fn (kernel/smpboot.c:160) > [ 1982.600053] ? __smpboot_create_thread (kernel/smpboot.c:105) > [ 1982.600053] kthread (kernel/kthread.c:210) > [ 1982.600053] ? wait_for_completion (kernel/sched/completion.c:77 kernel/sched/completion.c:93 kernel/sched/completion.c:101 kernel/sched/completion.c:122) > [ 1982.600053] ? kthread_create_on_node (kernel/kthread.c:176) > [ 1982.600053] ret_from_fork (arch/x86/kernel/entry_64.S:349) > [ 1982.600053] ? kthread_create_on_node (kernel/kthread.c:176) > [ 1982.600053] Code: 00 00 00 00 e8 63 ff ff ff 48 83 c4 08 b8 01 00 00 00 5b 5d c3 b8 01 00 00 00 c3 90 65 8b 04 25 a0 da 00 00 a9 00 00 0f 00 75 09 <0f> 0b 0f 1f 80 00 00 00 00 55 48 89 e5 e8 2f ff ff ff 5d c3 66 > All code > ======== > 0: 00 00 add %al,(%rax) > 2: 00 00 add %al,(%rax) > 4: e8 63 ff ff ff callq 0xffffffffffffff6c > 9: 48 83 c4 08 add $0x8,%rsp > d: b8 01 00 00 00 mov $0x1,%eax > 12: 5b pop %rbx > 13: 5d pop %rbp > 14: c3 retq > 15: b8 01 00 00 00 mov $0x1,%eax > 1a: c3 retq > 1b: 90 nop > 1c: 65 8b 04 25 a0 da 00 mov %gs:0xdaa0,%eax > 23: 00 > 24: a9 00 00 0f 00 test $0xf0000,%eax > 29: 75 09 jne 0x34 > 2b:* 0f 0b ud2 <-- trapping instruction > 2d: 0f 1f 80 00 00 00 00 nopl 0x0(%rax) > 34: 55 push %rbp > 35: 48 89 e5 mov %rsp,%rbp > 38: e8 2f ff ff ff callq 0xffffffffffffff6c > 3d: 5d pop %rbp > 3e: c3 retq > 3f: 66 data16 > ... > > Code starting with the faulting instruction > =========================================== > 0: 0f 0b ud2 > 2: 0f 1f 80 00 00 00 00 nopl 0x0(%rax) > 9: 55 push %rbp > a: 48 89 e5 mov %rsp,%rbp > d: e8 2f ff ff ff callq 0xffffffffffffff41 > 12: 5d pop %rbp > 13: c3 retq > 14: 66 data16 > ... > [ 1982.600053] RIP irq_work_run (kernel/irq_work.c:175 (discriminator 1)) > [ 1982.600053] RSP <ffff88036a5afbe0> > > > Thanks, > Sasha > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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