Hi, On Sat, Dec 21, 2024 at 10:06:10PM +0300, Sergey Bugaev wrote: > > In case you don't realize, there's more than one kernel map. > kernel_map is the main one, but there are also ipc_kernel_map and > device_io_map, which are submaps of kernel_map, and others could > potentially be added. > > The way to check if a map belongs to the kernel is vm_map_pmap(map) == > kernel_pmap. >
Oh, I did see `ipc_kernel_map` but didn't realize they were connected :( > > > To be honest, I'm trying to make the zzuf testsuit pass. Currently it fails > > on a test that exhausts memory[1] when the driver calls it with the memory > > limited to 256M [2][3]. > > > > [1] https://github.com/samhocevar/zzuf/blob/master/test/bug-memory.c > > [2] > > https://github.com/samhocevar/zzuf/blob/master/test/check-zzuf-M-max-memory#L41 > > [3] https://github.com/samhocevar/zzuf/blob/master/src/myfork.c#L261 > > Hm, so that code doesn't exactly seem to care that it's address space > size that it's limiting, as long as it's some way to limit memory > usage. > Correct. Whatever it makes malloc to fail after allocating ~256M that get setup through RLIMIT_AS. > > Now, limiting the amount of memory available to a task (or a group of > tasks) is of course also very much justified and logical. I'm saying: > let's think about the best design for this feature, and then, if it > ends up being aligned with a feature that Unix has, we can expose it > as that Unix feature at the Hurd/glibc level. But it may end up > looking more like cgroup's memory.max than like RLIMIT_AS, for > example. Ok, now I have to do some research on cgroups, hehe. > > On the other hand, resource accounting is famously not > properly doable in Mach — OSF Mach at least had ledgers (which were > never functional AFAIK), ours doesn't even do that. That's a pitty :( and also sounds like a lot of work to be done. > > Welp, I guess that does sound discouraging :| No, it's ok. I know kernel hacking is generally hard, just wanted to see how far I could go and it seems I'm getting near the boundaries of my skills :P
