On Thu, Nov 2, 2017 at 12:54 AM, Byungchul Park <byungchul.park@xxxxxxx> wrote: > On Wed, Nov 01, 2017 at 01:01:01PM +0100, Peter Zijlstra wrote: >> On Wed, Nov 01, 2017 at 05:59:27PM +0900, Byungchul Park wrote: >> > On Tue, Oct 31, 2017 at 04:10:24PM +0100, Peter Zijlstra wrote: >> > > On Tue, Oct 31, 2017 at 03:58:04PM +0100, Michal Hocko wrote: >> > > > On Tue 31-10-17 15:52:47, Peter Zijlstra 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? -- 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>
