2012/9/25 Frederic Weisbecker <fweis...@gmail.com>: > 2012/9/25 Sasha Levin <levinsasha...@gmail.com>: >> On 09/25/2012 01:06 AM, Frederic Weisbecker wrote: >>> 2012/9/25 Sasha Levin <levinsasha...@gmail.com>: >>>> On 09/25/2012 12:47 AM, Sasha Levin wrote: >>>>> - While I no longer see the warnings I've originally noticed, if I run >>>>> with Paul's last debug patch I see the following warning: >>>> >>>> Correction: Original warnings are still there, they just got buried in the >>>> huge spew that was caused by additional debug warnings >>>> so I've missed them initially. >>> >>> Are they the same? Could you send me your dmesg? >>> >>> Thanks. >>> >> >> Log is attached, you can go directly to 168.703017 when the warnings begin. > > Thanks! > > So here is the first relevant warning: > > [ 168.703017] ------------[ cut here ]------------ > [ 168.708117] WARNING: at kernel/rcutree.c:502 > rcu_eqs_exit_common+0x4a/0x3a0() > [ 168.710034] Pid: 7871, comm: trinity-child65 Tainted: G W > 3.6.0-rc6-next-20120924-sasha-00030-g71f256c #5 > [ 168.710034] Call Trace: > [ 168.710034] <IRQ> [<ffffffff811c737a>] ? rcu_eqs_exit_common+0x4a/0x3a0 > [ 168.710034] [<ffffffff811078b6>] warn_slowpath_common+0x86/0xb0 > [ 168.710034] [<ffffffff811079a5>] warn_slowpath_null+0x15/0x20 > [ 168.710034] [<ffffffff811c737a>] rcu_eqs_exit_common+0x4a/0x3a0 > [ 168.710034] [<ffffffff811c79cc>] rcu_eqs_exit+0x9c/0xb0 > [ 168.710034] [<ffffffff811c7a4c>] rcu_user_exit+0x6c/0xd0 > [ 168.710034] [<ffffffff8106eb1f>] do_general_protection+0x1f/0x170 > [ 168.710034] [<ffffffff83a0e624>] ? restore_args+0x30/0x30 > [ 168.710034] [<ffffffff83a0e875>] general_protection+0x25/0x30 > [ 168.710034] [<ffffffff810a3f06>] ? native_read_msr_safe+0x6/0x20 > [ 168.710034] [<ffffffff81a0b34b>] __rdmsr_safe_on_cpu+0x2b/0x50 > [ 168.710034] [<ffffffff819ec971>] ? list_del+0x11/0x40 > [ 168.710034] [<ffffffff811886dc>] > generic_smp_call_function_single_interrupt+0xec/0x120 > [ 168.710034] [<ffffffff81151147>] ? account_system_vtime+0xd7/0x140 > [ 168.710034] [<ffffffff81096f72>] > smp_call_function_single_interrupt+0x22/0x40 > [ 168.710034] [<ffffffff83a0fe2f>] call_function_single_interrupt+0x6f/0x80 > [ 168.710034] <EOI> [<ffffffff83a0e5f4>] ? retint_restore_args+0x13/0x13 > [ 168.710034] [<ffffffff811c7285>] ? rcu_user_enter+0x105/0x110 > [ 168.710034] [<ffffffff8107e06d>] syscall_trace_leave+0xfd/0x150 > [ 168.710034] [<ffffffff83a0f1ef>] int_check_syscall_exit_work+0x34/0x3d > [ 168.710034] ---[ end trace fd408dd21b70b87c ]--- > > This is an exception inside an interrupt, and the interrupt > interrupted RCU user mode. > And we have that nesting: > > rcu_irq_enter(); <--- irq entry > rcu_user_exit(); <--- exception entry > > And rcu_eqs_exit() doesn't handle that very well...
So either I should return immediately from rcu_user_exit() if we are in an interrupt, or we make rcu_user_exit() able to nest on rcu_irq_enter() :) -- 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/