[Bug 204789] New: Boot failure with more than 256G of memory

[Cameron Berkenpas]

Yep, the box comes up now, but with 256G memory as expected.

I'll get back to you on when I'll be able to bisect.

Thanks!

On 9/13/19 7:21 AM, Aneesh Kumar K.V wrote:
> Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com> writes:
>
>> Andrew Morton <akpm at linux-foundation.org> writes:
>>
>>> (switched to email.  Please respond via emailed reply-to-all, not via the
>>> bugzilla web interface).
>>>
>>> On Sun, 08 Sep 2019 00:04:26 +0000 bugzilla-daemon at bugzilla.kernel.org wrote:
>>>
>>>> https://bugzilla.kernel.org/show_bug.cgi?id=204789
>>>>
>>>>              Bug ID: 204789
>>>>             Summary: Boot failure with more than 256G of memory
>>>>             Product: Memory Management
>>>>             Version: 2.5
>>>>      Kernel Version: 5.2.x
>>>>            Hardware: PPC-64
>>>>                  OS: Linux
>>>>                Tree: Mainline
>>>>              Status: NEW
>>>>            Severity: high
>>>>            Priority: P1
>>>>           Component: Other
>>>>            Assignee: akpm at linux-foundation.org
>>>>            Reporter: cam at neo-zeon.de
>>>>          Regression: No
>>> "Yes" :)
>>>
>>>> Kernel series 5.2.x will not boot on my Talos II workstation with dual POWER9
>>>> 18 core processors and 512G of physical memory with disable_radix=yes and 4k
>>>> pages.
>>>>
>>>> 5.3-rc6 did not work either.
>>>>
>>>> 5.1 and earlier boot fine.
>>> Thanks.  It's probably best to report this on the powerpc list, cc'ed here.
>>>
>>>> I can get the system to boot IF I leave the Radix MMU enabled or if I boot a
>>>> kernel with 64k pages. I haven't yet tested enabling the Radix MMU with 64k
>>>> pages at the same time, but I suspect this would work. This is a system I
>>>> cannot take down TOO frequently.
>>>>
>>>> The system will also boot with the Radix MMU disabled and 4k pages with 256G or
>>>> less memory. Setting mem on the kernel CLI to 256G or less results in a
>>>> successful boot. Setting mem=257G or higher no Radix MMU and 4k pages and the
>>>> kernel will not boot.
>>>>
>>>> Petitboot comes up, but the system fails VERY early in boot in the serial
>>>> console with:
>>>> SIGTERM received, booting...
>>>> [   23.838858] kexec_core: Starting new kernel
>>>>
>>>> Early printk is enabled, and it never progresses any further.
>>>>
>>>> 5.1 boots just fine with the Radix MMU disabled and 4k pages.
>>>>
>>>> Unfortunately, I currently need 4k pages for bcache to work, and Radix MMU
>>>> disabled in order for FreeBSD 12.x to work under KVM so I'm sticking with
>>>> 5.1.21 for now.
>>>>
>>>> I have been unable to reproduce this issue in KVM.
>>>>
>>>> Here are my PCIe peripherals:
>>>> 1. Microsemi/Adaptec HBA 1100-4i SAS controller
>>>> 2. Megaraid 9316-16i SAS RAID controller.
>>>>
>>>> I've only tried little endian as this is a little endian install.
>> Will you be able to bisect this? I tried 4K PAGESIZE on P8 with upstream
>> kernel and I can't recreate the issuue.
>>
>> [root at ltc ~]# free -g
>>                total        used        free      shared  buff/cache   available
>> Mem:            495           0         494           0           0         493
>> Swap:             0           0           0
>> [root at ltc ~]# getconf PAGESIZE
>> 4096
>> [root at ltc ~]# grep Hash /proc/cpuinfo
>> MMU             : Hash
>>
>> I will see if I can get a P9 system with largemem
>>
> I was able to recreate this on a system that got memory above 16TB
> address. I guess your P9 system memory layout is also like that.
>
> Can you try this patch? It doesn't really fix the isssue, as in map the
> full 512GB of memory. But it do prevent the kernel crash.
>
> commit ebd05100344765fc3c030f0c257c2f9236fcd1ec
> Author: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
> Date:   Fri Sep 13 19:26:25 2019 +0530
>
>      powerpc/book3s64/hash/4k: 4k supports only 16TB linear mapping
>      
>      With commit: 0034d395f89d ("powerpc/mm/hash64: Map all the kernel regions in the
>      same 0xc range"), we now split the 64TB address range into 4 contexts each of
>      16TB. That implies we can do only 16TB linear mapping. Make sure we don't
>      add physical memory above 16TB if that is present in the system.
>      
>      Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
>
> diff --git a/arch/powerpc/include/asm/book3s/64/mmu.h b/arch/powerpc/include/asm/book3s/64/mmu.h
> index bb3deb76c951..86cce8189240 100644
> --- a/arch/powerpc/include/asm/book3s/64/mmu.h
> +++ b/arch/powerpc/include/asm/book3s/64/mmu.h
> @@ -35,12 +35,16 @@ extern struct mmu_psize_def mmu_psize_defs[MMU_PAGE_COUNT];
>    * memory requirements with large number of sections.
>    * 51 bits is the max physical real address on POWER9
>    */
> -#if defined(CONFIG_SPARSEMEM_VMEMMAP) && defined(CONFIG_SPARSEMEM_EXTREME) &&  \
> -	defined(CONFIG_PPC_64K_PAGES)
> +
> +#if defined(CONFIG_PPC_64K_PAGES)
> +#if defined(CONFIG_SPARSEMEM_VMEMMAP) && defined(CONFIG_SPARSEMEM_EXTREME)
>   #define MAX_PHYSMEM_BITS 51
>   #else
>   #define MAX_PHYSMEM_BITS 46
>   #endif
> +#else /* CONFIG_PPC_64K_PAGES */
> +#define MAX_PHYSMEM_BITS 44
> +#endif
>   
>   /* 64-bit classic hash table MMU */
>   #include <asm/book3s/64/mmu-hash.h>
>