On Mon, Jun 23, 2014 at 1:03 PM, Dave Hansen <dave.hansen@xxxxxxxxx> wrote: > On 06/23/2014 12:49 PM, Andy Lutomirski wrote: >> On 06/18/2014 02:44 AM, Qiaowei Ren wrote: >>> This patch adds one MPX specific mmap interface, which only handles >>> mpx related maps, including bounds table and bounds directory. >>> >>> In order to track MPX specific memory usage, this interface is added >>> to stick new vm_flag VM_MPX in the vma_area_struct when create a >>> bounds table or bounds directory. >> >> I imagine the linux-mm people would want to think about any new vm flag. >> Why is this needed? > > These tables can take huge amounts of memory. In the worst-case > scenario, the tables can be 4x the size of the data structure being > tracked. IOW, a 1-page structure can require 4 bounds-table pages. > > My expectation is that folks using MPX are going to be keen on figuring > out how much memory is being dedicated to it. With this feature, plus > some grepping in /proc/$pid/smaps one could take a pretty good stab at it. > > I know VM flags are scarce, and I'm open to other ways to skin this cat. > Can the new vm_operation "name" be use for this? The magic "always written to core dumps" feature might need to be reconsidered. There's also arch_vma_name, but I just finished removing for x86, and I'd be a little sad to see it come right back. --Andy -- 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>