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if CONFIG_PAGEALLOC is enabled then X86_FEATURE_PSE is disabled and all
the kernel physical RAM pagetables are set up as 4K pages. This is
needed so that CONFIG_PAGEALLOC can do finegrained mapping and unmapping
of pages.

as a side-effect though, the total size of memory allocated as kernel
pagetables increases significantly. All these pagetables are allocated
via alloc_bootmem_low_pages(), straight out of the lowmem DMA pool. If
the system has enough RAM and a large kernel image then almost all of
the 16 MB lowmem DMA pool is allocated to the image and to pagetables -
leaving no space for __GFP_DMA allocations.

this results in drivers failing and the bootup hanging:

 swapper invoked oom-killer: gfp_mask=0x80d1, order=0, oomkilladj=0
  [<4015059f>] out_of_memory+0x17f/0x1c0
  [<40151f3c>] __alloc_pages+0x37c/0x3a0
  [<40168cd7>] slob_new_page+0x37/0x50
  [<40168dff>] slob_alloc+0x10f/0x190
  [<40169010>] __kmalloc_node+0x80/0x90
  [<405a17e3>] scsi_host...