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SubjectRe: [crash] Re: Latest brk patchset
Jeremy Fitzhardinge wrote:
> Yinghai Lu wrote:
>> could be max_pfn_mapped change in head_32.S that reduce mapping range
>> to _end only.
> Yes, I would say you're right. Trimming the mapping to _end only leaves
> the space under the kernel avaliable for allocating pagetable from e820
> space. In this case we've got DEBUG_PAGEALLOC enabled, which inhibits
> the use of PSE, and BIOS corruption checking on, which eats a chunk of
> low memory. In combination, there's only 0x8f000 bytes free below the
> kernel, and it needs 0xe1000 to allocate for pagetables.
> Reverting 2bd2753ff46346543ab92e80df9d96366e21baa5 fixes the problem for
> me, though it does result in a kernel with a 73MB BSS...

Waitaminute... there is no way we could end up with 73 MB page tables
unless something is seriously screwy. Even with PAE and !PSE, we only
get 2 MB worth of page tables for each 1 GB mapped -- even with a 4:4
scheme this is only 8 MB.


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