(2013/05/08 0:08), Vivek Goyal wrote: > On Tue, May 07, 2013 at 04:56:46PM +0900, HATAYAMA Daisuke wrote: >> (2013/04/30 4:36), Vivek Goyal wrote: >>> On Sat, Apr 13, 2013 at 09:21:33AM +0900, HATAYAMA Daisuke wrote: >>> >>> [..] >>>> ELF notes are per-cpu, so total size of ELF note segments increases >>>> according to the number of CPUs. The current maximum number of CPUs on >>>> x86_64 is 5192, and there's already system with 4192 CPUs in SGI, >>>> where total size amounts to 1MB. This can be larger in the neare >>>> futrue or possibly even now on another architecture. Thus, to avoid >>>> the case where memory allocation for large block fails, we allocate >>>> vmcore objects per pages. >>> >>> IIRC, eric had suggested using vmalloc() and remap_vmalloc_range(). What's >>> wrong with that? That should keep your vc_list relatively smaller. >>> >> >> Yes, it's handy if it's possible to remap them in vmalloc space, but >> the problem here is that remap_vmalloc_range requires the first >> argument vma to cover full range of the requested map. This becomes >> problem when requested area for mmap() overlaps multiple objects, >> for example, ELF headers and memory refered to by the first PT_LOAD >> program header. >> >> To use remap_vmalloc_range, it's necessary to prepare a new variant >> similar to remap_pfn_range by which we can remap different objects >> separately to a single vma. > > Ok. Is it hard to prepare one such variant. If we can write one, it will > simplify the vmcore code. I'll try to write it. Although I avoided implementing it once, now it looks relatively easy to implement thanks to vm_insert_page, which does all essential thing. All I have to do should be consider sanity-check only. -- Thanks. HATAYAMA, Daisuke
