Lemote-3a-itx-a1101 kernel/PMON bug (Was: Bug#858405: xmlto: intermittent Segmentation fault when building manpages for libreswan on mips64el)

Hi,

[drop some CCs since this is not directly related to the xmlto bug]

On 24/03/17 09:36, YunQiang Su wrote:
> On Fri, Mar 24, 2017 at 1:06 AM, James Cowgill <[email protected]> wrote:
>> I believe any of the following will fix this (but have not all been tested):
>> - Reduce the stack usage in xsltproc (the upstream bug)
>> - Upgrade the relevant buildds to Linux >= 4.1
>> - Apply d1fd836dcf00 to jessie's kernel
>> - Disable PIE in xsltproc.
>> - Run xsltproc inside setarch -L / setarch -R
>>
> 
> we have some trouble to run newer kernel on some Loongson machines,
> as their pmon can only load initrd with limit size.
> So backports patch may ideal for us, now.

Are you referring to this issue?
https://lists.debian.org/debian-mips/2016/01/msg00009.html

This does only affect some Loongson machines. I think all the buildds
can be safely upgraded to 4.9 except for mipsel-manda-01 which has the
buggy PMON.

Looking at the bug again, all the extra .bss space comes from the giant
mem_section array which is always used on Loongson due to
STATIC_SPARSEMEM being enabled. I am wondering if this patch might help
(and if it works for multi-node Loongsons like the 3B). The Loongson
memory initialization code takes a different path to other mips
sub-arches and avoids calling memory_present until the very end, so it
might not need STATIC_SPARSEMEM?

(patch is completely untested)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 7baddfa0e229..3bbb454ab2f5 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2559,7 +2559,7 @@ config ARCH_DISCONTIGMEM_ENABLE

 config ARCH_SPARSEMEM_ENABLE
        bool
-       select SPARSEMEM_STATIC
+       select SPARSEMEM_STATIC if !MACH_LOONGSON64

 config NUMA
        bool "NUMA Support"

Thanks,
James

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