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

[Andrew Morton]

(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.
> 
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