On Tue, 2019-10-08 at 09:13 -0400, Steven Rostedt wrote: > On Tue, 8 Oct 2019 10:15:10 +0200 > Petr Mladek <pmladek@xxxxxxxx> wrote: > > > There are basically three possibilities: > > > > 1. Do crazy exercises with locks all around the kernel to > > avoid the deadlocks. It is usually not worth it. And > > it is a "whack a mole" approach. > > > > 2. Use printk_deferred() in problematic code paths. It is > > a "whack a mole" approach as well. And we would end up > > with printk_deferred() used almost everywhere. > > > > 3. Always deffer the console handling in printk(). This would > > help also to avoid soft lockups. Several people pushed > > against this last few years because it might reduce > > the chance to see the message in case of system crash. > > > > As I said, there has finally been agreement to always do > > the offload few weeks ago. John Ogness is working on it. > > So we might have the systematic solution for these deadlocks > > rather sooner than later. > > Another solution is to add the printk_deferred() in these places that > cause lockdep splats, and when John's work is done, it would be easy to > grep for them and remove them as they would no longer be needed. > > This way we don't play whack-a-mole forever (only until we have a > proper solution) and everyone is happy that we no longer have these > false positive or I-don't-care lockdep splats which hide real lockdep > splats because lockdep shuts off as soon as it discovers its first > splat. I feel like that is what I trying to do, but there seems a lot of resistances with that approach where pragmatism met with perfectionism.
