On Wed, Aug 06, 2014 at 05:12:24AM +0800, Fengguang Wu wrote:
> Greetings,
>
> Here is a microcode/load_module error triggered by debug check commit
> 64c2181bc433b17f04da8fe8592aa83cceac9606 ("sched: Debug nested sleeps"):
>
> [ 6.010476] microcode: CPU0 sig=0x106a3, pf=0x1, revision=0x1
> [ 6.011896] microcode: CPU1 sig=0x106a3, pf=0x1, revision=0x1
> [ 6.020554] ------------[ cut here ]------------
> [ 6.021988] WARNING: CPU: 0 PID: 1444 at kernel/sched/core.c:7094
> __might_sleep+0x51/0x16f()
> [ 6.024909] do not call blocking ops when !TASK_RUNNING; state=1 set at
> [<ffffffff81111e4c>] prepare_to_wait_event+0xb2/0xee
> [ 6.026998] Modules linked in: microcode(+)
> [ 6.027998] CPU: 0 PID: 1444 Comm: modprobe Not tainted
> 3.16.0-02034-gf5d04af #1
> [ 6.029603] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> [ 6.030674] 0000000000000000 ffff88003da2bd00 ffffffff819c7cb6
> ffff88003da2bd48
> [ 6.032577] ffff88003da2bd38 ffffffff810e1dd0 ffffffff810ff665
> ffff88003d91b7e0
> [ 6.034417] ffffffff81cd5c89 0000000000000061 0000000000000000
> ffff88003da2bd98
> [ 6.036236] Call Trace:
> [ 6.036908] [<ffffffff819c7cb6>] dump_stack+0x4d/0x66
> [ 6.037894] [<ffffffff810e1dd0>] warn_slowpath_common+0x7f/0x98
> [ 6.038601] microcode: Microcode Update Driver: v2.00
> <[email protected]>, Peter Oruba
> [ 6.040761] [<ffffffff810ff665>] ? __might_sleep+0x51/0x16f
> [ 6.041861] [<ffffffff810e1e35>] warn_slowpath_fmt+0x4c/0x4e
> [ 6.043034] [<ffffffff811c06d7>] ? __vmalloc_node_range+0x18d/0x1f1
> [ 6.044270] [<ffffffff81141bf6>] ? module_alloc_update_bounds+0x14/0x5f
> [ 6.045458] [<ffffffff81111e4c>] ? prepare_to_wait_event+0xb2/0xee
> [ 6.046592] [<ffffffff81111e4c>] ? prepare_to_wait_event+0xb2/0xee
> [ 6.048258] [<ffffffff810ff665>] __might_sleep+0x51/0x16f
> [ 6.049501] [<ffffffff819cda15>] mutex_lock+0x20/0x42
> [ 6.050601] [<ffffffff811403c0>] finished_loading+0x19/0x63
> [ 6.051823] [<ffffffff8114217d>] load_module+0x522/0x1f0a
> [ 6.053086] [<ffffffff81492e1b>] ? trace_hardirqs_on_thunk+0x3a/0x3c
> [ 6.054498] [<ffffffff819d0564>] ? retint_restore_args+0x13/0x13
> [ 6.055607] [<ffffffff81111f6c>] ? wait_woken+0x69/0x69
> [ 6.056645] [<ffffffff81143c2f>] SyS_init_module+0xca/0xd9
> [ 6.057637] [<ffffffff819cfa29>] system_call_fastpath+0x16/0x1b
> [ 6.058751] ---[ end trace ee9cd23bc6a36c85 ]---
> [ 6.098452] ------------[ cut here ]------------That looks like a genuine bug; add_unformed_module() calls wait_event_interruptible(.condition = finished_loading()), and finished_loading() takes a mutex. Compile tested only.. will stuff in the next tree. --- Subject: module: Fix nested sleep From: Peter Zijlstra <[email protected]> Date: Thu Aug 7 12:38:16 CEST 2014 Cc: Rusty Russell <[email protected]> Reported-by: Fengguang Wu <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> Link: http://lkml.kernel.org/n/[email protected] --- kernel/module.c | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-) --- a/kernel/module.c +++ b/kernel/module.c @@ -3094,6 +3094,28 @@ static int may_init_module(void) return 0; } +int wait_finished_loading(struct module *mod) +{ + DEFINE_WAIT_FUNC(wait, woken_wake_function); + int ret = 0; + + add_wait_queue(&module_wq, &wait); + for (;;) { + if (finished_loading(mod->name)) + break; + + if (signal_pending_state(TASK_INTERRUPTIBLE, current)) { + ret = -ERESTARTSYS; + break; + } + + wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); + } + remove_wait_queue(&module_wq, &wait); + + return ret; +} + /* * We try to place it in the list now to make sure it's unique before * we dedicate too many resources. In particular, temporary percpu @@ -3114,8 +3136,8 @@ static int add_unformed_module(struct mo || old->state == MODULE_STATE_UNFORMED) { /* Wait in case it fails to load. */ mutex_unlock(&module_mutex); - err = wait_event_interruptible(module_wq, - finished_loading(mod->name)); + + err = wait_finished_loading(mod); if (err) goto out_unlocked; goto again;
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