On Tue, Dec 22, 2020 at 11:57 PM Christoph Hellwig <hch@xxxxxx> wrote: > > On Tue, Dec 22, 2020 at 09:48:43AM -0800, Suren Baghdasaryan wrote: > > Thanks for the feedback! The use case is userspace memory reaping > > similar to oom-reaper. Detailed justification is here: > > https://lore.kernel.org/linux-mm/20201124053943.1684874-1-surenb@xxxxxxxxxx > > Given that this new variant of process_madvise > > a) does not work on an address range True, however I can see other madvise flavors that could be used on the entire process. For example process_madvise(MADV_PAGEOUT) could be used to "shrink" an entire inactive background process. > b) is destructive I agree that memory reaping might be the only case when a destructive process_madvise() makes sense. Unless the target process is dying, a destructive process_madvise() would need coordination with the target process, and if it's coordinated then the target might as well call normal madvise() itself. > c) doesn't share much code at all with the rest of process_madvise It actually does reuse a considerable part of the code, but the same code can be refactored and reused either way. > > Why not add a proper separate syscall? I think my answer to (a) is one justification for allowing process_madvise() to operate on the entire process. Also MADV_DONTNEED seems quite suitable for this operation. Considering the above answers, are you still leaning towards a separate syscall? > > -- > To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@xxxxxxxxxxx. >
