Re: [RFC 7/7] mm: madvise support MADV_ANONYMOUS_FILTER and MADV_FILE_FILTER

On Tue, May 28, 2019 at 01:31:13AM -0700, Daniel Colascione wrote:

On Tue, May 28, 2019 at 1:14 AM Minchan Kim [off-list ref] wrote:

quoted

if we went with the per vma fd approach then you would get this

quoted

feature automatically because map_files would refer to file backed
mappings while map_anon could refer only to anonymous mappings.

The reason to add such filter option is to avoid the parsing overhead
so map_anon wouldn't be helpful.

Without chiming on whether the filter option is a good idea, I'd like
to suggest that providing an efficient binary interfaces for pulling
memory map information out of processes.  Some single-system-call
method for retrieving a binary snapshot of a process's address space
complete with attributes (selectable, like statx?) for each VMA would
reduce complexity and increase performance in a variety of areas,
e.g., Android memory map debugging commands.

I agree it's the best we can get *generally*.
Michal, any opinion?