[PATCH v3 18/21] vmcore: check if vmcore objects satify mmap()'s page-size boundary requirement

[Eric W. Biederman]

HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com> writes:

> OK, rigorously, suceess or faliure of the requested free pages
> allocation depends on actual memory layout at the 2nd kernel boot. To
> increase the possibility of allocating memory, we have no method but
> reserve more memory for the 2nd kernel now.

Good enough.   If there are fragmentation issues that cause allocation
problems on larger boxes we can use vmalloc and remap_vmalloc_range, but
we certainly don't need to start there.

Especialy as for most 8 or 16 core boxes we are talking about a 4KiB or
an 8KiBP allocation.  Aka order 0 or order 1.

Adding more memory is also useful.  It is important in general to keep
the amount of memory needed for the kdump kernel low.

Eric