On 07/14/14 19:13, Christoph Lameter wrote: > On Sun, 13 Jul 2014, Andrey Ryabinin wrote: > >>> How does that work when memory is sparsely populated? >>> >> >> Sparsemem configurations currently may not work with kasan. >> I suppose I will have to move shadow area to vmalloc address space and >> make it (shadow) sparse too if needed. > > Well it seems to work with sparsemem / vmemmap? So non vmmemmapped configs > of sparsemem only. vmemmmap can also handle holes in memory. > > Not sure. This sparsemem/vmemmap thing is kinda new to me, so I need to dig some more to understand how it iтteracts with kasan. As far as I understand the main problem with sparsemem & kasan is shadow allocation: unsigned long lowmem_size = (unsigned long)high_memory - PAGE_OFFSET; shadow_size = lowmem_size >> KASAN_SHADOW_SCALE_SHIFT; shadow_phys_start = memblock_alloc(shadow_size, PAGE_SIZE); If we don't have one big enough physically contiguous block for shadow it will fail. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>