Re: PROBLEM: 4.15.0-rc3 APIC causes lockups on Core 2 Duo laptop

[Dou Liyang <douly.fnst@cn.fujitsu.com>]

Hi Alexandru,

At 12/24/2017 04:01 AM, Alexandru Chirvasitu wrote:
> On Sat, Dec 23, 2017 at 02:32:52PM +0100, Thomas Gleixner wrote:
>> On Sat, 23 Dec 2017, Dexuan Cui wrote:
>>
>>>> From: Alexandru Chirvasitu [mailto:achirvasub@gmail.com]
>>>> Sent: Friday, December 22, 2017 14:29
>>>>
>>>> The output of that precise command run just now on a freshly-compiled
>>>> copy of that commit is attached.
>>>>
>>>> On Fri, Dec 22, 2017 at 09:31:28PM +0000, Dexuan Cui wrote:
>>>>>> From: Alexandru Chirvasitu [mailto:achirvasub@gmail.com]
>>>>>> Sent: Friday, December 22, 2017 06:21
>>>>>>
>>>>>> In the absence of logs, the best I can do at the moment is attach a
>>>>>> picture of the screen I am presented with on the  boot
>>>>>> attempt.
>>>>>> Alex
>>>>>
>>>>> The panic happens in irq_matrix_assign_system+0x4e/0xd0 in your picture.
>>>>> IMO we should find which line of code causes the panic. I suppose
>>>>> "objdump -D kernel/irq/matrix.o" can help to do that.
>>>>>
>>>>> Thanks,
>>>>> -- Dexuan
>>>
>>> The BUG_ON panic happens at line 147:
>>>                     BUG_ON(!test_and_clear_bit(bit, cm->alloc_map));
>>>

There are 2 bugs in your laptop:

   1. Hard lockups on both CPUs after login
   2. panic with "apic=debug"

For the 2th bug, please try the following patch(need Thomas confirmation
:) ) in Linux 4.15-rc5. I think it can fix the panic.

If the 2th bug fixed, let's back to the 1th bug:

Is Linus current head 4.15-rc5 bad as well?

If yes, Please using "apic=debug" and give the dmesg log.

Thanks,
	dou.

------------------------8<-------------------------------------------

irq/matrix: Remove the overused BUGON() in irq_matrix_assign_system()

Currently, x86 marks the preallocated legacy interrupts when initializing
IRQ(native_init_IRQ), but will clear them if they are not activated in
vector_configure_legacy().

So, in irq_matrix_assign_system(), replacing an legacy vector which may
not allocated in a cpumap->alloc_map[] with a system vector will trigger
the BUGON();

Remove the BUGON().

Signed-off-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
---
  kernel/irq/matrix.c | 5 +++--
  1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/matrix.c b/kernel/irq/matrix.c
index 0ba0dd8863a7..876cbeab9ca2 100644
--- a/kernel/irq/matrix.c
+++ b/kernel/irq/matrix.c
@@ -143,11 +143,12 @@ void irq_matrix_assign_system(struct irq_matrix 
*m, unsigned int bit,
  	BUG_ON(m->online_maps > 1 || (m->online_maps && !replace));

  	set_bit(bit, m->system_map);
-	if (replace) {
-		BUG_ON(!test_and_clear_bit(bit, cm->alloc_map));
+
+	if (replace && test_and_clear_bit(bit, cm->alloc_map)){
  		cm->allocated--;
  		m->total_allocated--;
  	}
+
  	if (bit >= m->alloc_start && bit < m->alloc_end)
  		m->systembits_inalloc++;

--