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

From: Eric W. Biederman
Date: Thu Mar 21 2013 - 03:23:15 EST

HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx> 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.


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