On Sat, Jan 5, 2019 at 12:43 PM Jiri Kosina <jikos@xxxxxxxxxx> wrote: > > > Who actually _uses_ mincore()? That's probably the best guide to what > > we should do. Maybe they open the file read-only even if they are the > > owner, and we really should look at file ownership instead. > > Yeah, well > > https://codesearch.debian.net/search?q=mincore > > is a bit too much mess to get some idea quickly I am afraid. Yeah, heh. And the first hit is 'fincore', which probably nobody cares about anyway, but it does fd = open (name, O_RDONLY) .. mmap(window, len, PROT_NONE, MAP_PRIVATE, .. so if we want to keep that working, we'd really need to actually check file ownership rather than just looking at f_mode. But I don't know if anybody *uses* and cares about fincore, and it's particularly questionable for non-root users. And the Android go runtime code seems to oddly use mincore to figure out page size: // try using mincore to detect the physical page size. // mincore should return EINVAL when address is not a multiple of system page size. which is all kinds of odd, but whatever.. Why mincore, rather than something sane and obvious like mmap? Don't ask me... Anyway, the Debian code search just results in mostly non-present stuff. It's sad that google code search is no more. It was great for exactly these kinds of questions. The mono runtime seems to have some mono_pages_not_faulted() function, but I don't know if people use it for file mappings, and I couldn't find any interesting users of it. I didn't find anything that seems to really care, but I gave up after a few pages of really boring stuff. Linus
