On Wed, Feb 14, 2018 at 4:44 PM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: >> >> > > > [...] >> >> > > > > If we want to save those stacks; we have to save a stacktrace on _every_ >> >> > > > > lock acquire, simply because we never know ahead of time if there will >> >> > > > > be a new link. Doing this is _expensive_. >> >> > > > > >> >> > > > > Furthermore, the space into which we store stacktraces is limited; >> >> > > > > since memory allocators use locks we can't very well use dynamic memory >> >> > > > > for lockdep -- that would give recursive and robustness issues. >> >> > >> >> > I agree with all you said. >> >> > >> >> > But, I have a better idea, that is, to save only the caller's ip of each >> >> > acquisition as an additional information? Of course, it's not enough in >> >> > some cases, but it's cheep and better than doing nothing. >> >> > >> >> > For example, when building A->B, let's save not only full stack of B, >> >> > but also caller's ip of A together, then use them on warning like: >> >> >> >> Like said; I've never really had trouble finding where we take A. And >> > >> > Me, either, since I know the way. But I've seen many guys who got >> > confused with it, which is why I suggested it. >> > >> > But, leave it if you don't think so. >> > >> >> for the most difficult cases, just the IP isn't too useful either. >> >> >> >> So that would solve a non problem while leaving the real problem. >> >> >> Hi, >> >> What's the status of this? Was any patch submitted for this? > > This http://lkml.kernel.org/r/20171116120535.23765-1-mhocko@xxxxxxxxxx? Thanks Let's tell syzbot: #syz fix: mm: drop hotplug lock from lru_add_drain_all() -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
