On Tue, Dec 15, 2015 at 2:41 PM, Dmitry Vyukov <dvyu...@google.com> wrote: > On Tue, Dec 15, 2015 at 2:39 PM, Peter Zijlstra <pet...@infradead.org> wrote: >> On Tue, Dec 15, 2015 at 02:01:32PM +0100, Dmitry Vyukov wrote: >> >> >>> Call Trace: >>> <IRQ> [<ffffffff810e5e38>] sched_show_task+0x148/0x250 >>> kernel/sched/core.c:4934 >> >> <snip> >> >>> [<ffffffff823ff46c>] apic_timer_interrupt+0x8c/0xa0 >>> arch/x86/entry/entry_64.S:520 >>> >>> <EOI> [< inline >] ? arch_local_irq_enable >>> ./arch/x86/include/asm/paravirt.h:816 >>> <EOI> [< inline >] ? __raw_spin_unlock_irq >>> include/linux/spinlock_api_smp.h:170 >>> <EOI> [<ffffffff823fde9e>] ? _raw_spin_unlock_irq+0x2e/0x40 >>> kernel/locking/spinlock.c:199 >>> [< inline >] ? __raw_spin_unlock_irq >>> include/linux/spinlock_api_smp.h:170 >>> [<ffffffff823fde97>] ? _raw_spin_unlock_irq+0x27/0x40 >>> kernel/locking/spinlock.c:199 >>> [<ffffffff8119c8bb>] perf_install_in_context+0x6b/0xf0 >>> kernel/events/core.c:2173 >>> [<ffffffff811a492c>] SYSC_perf_event_open+0x63c/0xe40 >>> kernel/events/core.c:8565 >>> [<ffffffff811a7739>] SyS_perf_event_open+0x9/0x10 kernel/events/core.c:8261 >>> [<ffffffff823fe676>] entry_SYSCALL_64_fastpath+0x16/0x7a >>> arch/x86/entry/entry_64.S:185 >> >> >> So this looks like its stuck in the retry loop in >> perf_install_in_context(). We do the raw_spin_unlock_irq(), which allows >> the above watchdog interrupt to happen, but make no progress. >> >> This means the task_function_call() thing keeps failing, which is >> extremely unlikely. >> >> Let me have a play with your test-case to see if it reproduces. > > Yeah, both perf_install_in_context and perf_remove_from_context hang > in a very similar loops.
Note that the test uses cpu%4 because I have 4 cpus. Here is how I start qemu: -numa node,nodeid=0,cpus=0-1 -numa node,nodeid=1,cpus=2-3 -smp sockets=2,cores=2,threads=1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
