Tejun Heo wrote:
> Tejun Heo wrote:
>   
>> Hello,
>>
>> Sachin Sant wrote:
>>     
>>> <4>PERCPU: chunk 1 relocating -1 -> 18 c0000000db70fb00
>>> <c0000000db70fb00:c0000000db70fb00>
>>> <4>PERCPU: relocated <c000000001120320:c000000001120320>
>>> <4>PERCPU: chunk 1 relocating 18 -> 16 c0000000db70fb00
>>> <c000000001120320:c000000001120320>
>>> <4>PERCPU: relocated <c000000001120300:c000000001120300>
>>> <4>PERCPU: chunk 1, alloc pages [0,1)
>>> <4>PERCPU: chunk 1, map pages [0,1)
>>> <4>PERCPU: map 0xd00007fffff00000, 1 pages 53544
>>> <4>PERCPU: map 0xd00007fffff80000, 1 pages 53545
>>> <4>PERCPU: chunk 1, will clear 4096b/unit d00007fffff00000 d00007fffff80000
>>> <3>INFO: RCU detected CPU 0 stall (t=1000 jiffies)
>>>       
>> This supports my hypothesis.  This is the first area being allocated
>> from a dynamic chunk and cleared.  PFN 53544 and 53545 have been
>> allocated and successfully mapped to 0xd00007fffff00000 and
>> 0xd00007fffff80000 using map_kernel_range_noflush() but when those
>> addresses are actually accessed, we end up with infinite faults.  The
>> fault handler probably thinks that the fault has been handled
>> correctly but, when the control is returned, the processor faults
>> again.  Benjamin, I'm way out of my depth here, can you please help?
>>
>> Oh, one more simple experiment.  Sachin, does the following patch make
>> any difference?
>>     
With this patch applied the machine boots OK :-)

Have attached the boot log. Note that this boot log is
from a different machine, but the reported problem can be
recreate on this machine as well.

Thanks
-Sachin

>
> Oops, the patch should look like the following.
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 69511e6..37ab9e2 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -2056,7 +2056,8 @@ static unsigned long pvm_determine_end(struct vmap_area **pnext,
>  				       struct vmap_area **pprev,
>  				       unsigned long align)
>  {
> -	const unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
> +	const unsigned long vmalloc_start = ALIGN(VMALLOC_START, align);
> +	const unsigned long vmalloc_end = vmalloc_start + (512 << 20);
>  	unsigned long addr;
>
>  	if (*pnext)
> @@ -2102,7 +2103,7 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
>  				     size_t align, gfp_t gfp_mask)
>  {
>  	const unsigned long vmalloc_start = ALIGN(VMALLOC_START, align);
> -	const unsigned long vmalloc_end = VMALLOC_END & ~(align - 1);
> +	const unsigned long vmalloc_end = vmalloc_start + (512 << 20);
>  	struct vmap_area **vas, *prev, *next;
>  	struct vm_struct **vms;
>  	int area, area2, last_area, term_area;
>
>   


-- 

---------------------------------
Sachin Sant
IBM Linux Technology Center
India Systems and Technology Labs
Bangalore, India
---------------------------------