On Thu 04-05-23 08:08:13, Suren Baghdasaryan wrote: > On Thu, May 4, 2023 at 2:07 AM Michal Hocko <mhocko@xxxxxxxx> wrote: [...] > > e.g. is it really interesting to know that there is a likely memory > > leak in seq_file proper doing and allocation? No as it is the specific > > implementation using seq_file that is leaking most likely. There are > > other examples like that See? > > Yes, I see that. One level tracking does not provide all the > information needed to track such issues. Something more informative > would cost more. That's why our proposal is to have a light-weight > mechanism to get a high level picture and then be able to zoom into a > specific area using context capture. If you have ideas to improve > this, I'm open to suggestions. Well, I think that a more scalable approach would be to not track in callers but in the allocator itself. The full stack trace might not be all that important or interesting and maybe even increase the overall overhead but a partial one with a configurable depth would sound more interesting to me. A per cache hastable indexed by stack trace reference and extending slab metadata to store the reference for kfree path won't be free but the overhead might be just acceptable. If the stack unwinding is really too expensive for tracking another option would be to add code tags dynamically to the compiled kernel without any actual code changes. I can imagine the tracing infrastructure could be used for that or maybe even consider compiler plugins to inject code for functions marked as allocators. So the kernel could be instrumented even without eny userspace tooling required by users directly. -- Michal Hocko SUSE Labs
