On Tuesday 09 September 2008 03:52, Krzysztof Helt wrote:

quoted text
> alloc_vmap_area within(e07f0000-fffb7000) size=801000
> returns=(e0880000-e1081000)
> alloc_vmap_area within(e07f0000-fffb7000) size=2000
> returns=(e07f0000-e07f2000)
> alloc_vmap_area within(e07f0000-fffb7000) size=2000
> returns=(e0822000-e0824000) 
> vunmap_page_range (e07f0000-e07f2000 size=2000)
> free_vmap_area (e07f0000-e07f2000 size=2000)

quoted text
> alloc_vmap_area within(e07f0000-fffb7000) size=5000
> returns=(e07f0000-e07f5000)
> ------------[ cut here ]------------ 
> WARNING: at mm/vmalloc.c:40 check_pte_range+0x83/0x90()

Thanks for that, it clearly shows the virtual address allocator
is allowing an overlapping allocation after a vm_unmap_aliases()
call. Unfortunately, my "random" test case happened not to
trigger that... I should have paid more attention to edge cases
rather than just random testing.

Anyway, I hope this fix should solve the problem for you? (it
fixes it here)