Re: [PATCH] init: Add lockdep annotation to kthreadd_done completer

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi Andrew,

On 8/11/23 19:44, Helge Deller wrote:
On 8/11/23 18:43, Andrew Morton wrote:
On Fri, 11 Aug 2023 18:04:22 +0200 Helge Deller <deller@xxxxxx> wrote:

Add the missing lockdep annotation to avoid this warning:

  INFO: trying to register non-static key.
  The code is fine but needs lockdep annotation, or maybe
  you didn't initialize this object before use?
  turning off the locking correctness validator.
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.5.0-rc5+ #681
  Hardware name: 9000/785/C3700
  Backtrace:
   [<000000004030bcd0>] show_stack+0x74/0xb0
   [<0000000041469c7c>] dump_stack_lvl+0x104/0x180
   [<0000000041469d2c>] dump_stack+0x34/0x48
   [<000000004040e5b4>] register_lock_class+0xd24/0xd30
   [<000000004040c21c>] __lock_acquire.isra.0+0xb4/0xac8
   [<000000004040cd60>] lock_acquire+0x130/0x298
   [<000000004146df54>] _raw_spin_lock_irq+0x60/0xb8
   [<0000000041472044>] wait_for_completion+0xa0/0x2d0
   [<000000004146b544>] kernel_init+0x48/0x3a8
   [<0000000040302020>] ret_from_kernel_thread+0x20/0x28

...

--- a/init/main.c
+++ b/init/main.c
@@ -682,6 +682,8 @@ noinline void __ref __noreturn rest_init(void)
      struct task_struct *tsk;
      int pid;

+    init_completion(&kthreadd_done);
+
      rcu_scheduler_starting();
      /*
       * We need to spawn init first so that it obtains pid 1, however

This is pretty old code, as is the page_alloc_init_late() change.  Do
we know why this warning has just turned up lately?

[dropped Helge's assumptions that it's related to parisc's unusual
__ARCH_SPIN_LOCK_UNLOCKED_VAL value. It turned out to be wrong.

Now I was able to trace down why I see those lockdep warnings on parisc.
The short answer is:
On parisc the _initdata section lies outside of the usual kernel
_stext ... _end range. Lockdep calls static_obj() which currently assumes
that __initdata is inside that range and thus returns "false".
That's why lockdep then reports
	INFO: trying to register non-static key.
which is wrong.

Please drop those 3 lockdep patches from your mm-queue:

mm-add-lockdep-annotation-to-pgdat_init_all_done_comp-completer.patch
init-add-lockdep-annotation-to-kthreadd_done-completer.patch
watchdog-fix-lockdep-warning.patch

I'll send one single patch which fixes static_obj() instead.

Thanks,
Helge




[Index of Archives]     [Linux SoC]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux