On Tue, 2019-10-08 at 14:39 +0200, Michal Hocko wrote: > On Tue 08-10-19 08:00:43, Qian Cai wrote: > > > > > > > On Oct 8, 2019, at 6:39 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > > > > > Have you actually triggered any real deadlock? With a zone->lock in > > > place it would be pretty clear with hard lockups detected. > > > > Yes, I did trigger here and there, and those lockdep splats are > > especially useful to figure out why. > > Can you provide a lockdep splat from an actual deadlock please? I am > sorry but your responses tend to be really cryptic and I never know when > you are talking about actual deadlocks and lockdep splats. I have asked > about the former several times never receiving a specific answer. It is very time-consuming to confirm a lockdep splat is 100% matching a deadlock giving that it is not able to reproduce on will yet, so when I did encounter a memory offline deadlock where "echo offline > memory/state" just hang, but there is no hard lockup probably because the hard lockup detector did not work properly for some reasons or it keep trying to acquire a spin lock that only keep the CPU 100%.
