On Wed, 2022-05-11 at 17:22 -0300, Guilherme G. Piccoli wrote: > On 10/05/2022 11:28, Petr Mladek wrote: > > [...] > > It is not clear to me why user mode linux should not care about > > the other notifiers. It might be because I do not know much > > about the user mode linux. > > > > Is the because they always create core dump or are never running > > in a hypervisor or ...? > > > > AFAIK, the notifiers do many different things. For example, there > > is a notifier that disables RCU watchdog, print some extra > > information. Why none of them make sense here? > > > > Hi Petr, my understanding is that UML is a form of running Linux as a > regular userspace process for testing purposes. Correct. > With that said, as soon > as we exit in the error path, less "pollution" would happen, so users > can use GDB to debug the core dump for example. > > In later patches of this series (when we split the panic notifiers in 3 > lists) these UML notifiers run in the pre-reboot list, so they run after > the informational notifiers for example (in the default level). > But without the list split we cannot order properly, so my gut feeling > is that makes sense to run them rather earlier than later in the panic > process... > > Maybe Anton / Johannes / Richard could give their opinions - appreciate > that, I'm not attached to the priority here, it's more about users' > common usage of UML I can think of... It's hard to say ... In a sense I'm not sure it matters? OTOH something like the ftrace dump notifier (kernel/trace/trace.c) might still be useful to run before the mconsole and coredump ones, even if you could probably use gdb to figure out the information. Personally, I don't have a scenario where I'd care about the trace buffers though, and most of the others I found would seem irrelevant (drivers that aren't even compiled, hung tasks won't really happen since we exit immediately, and similar.) johannes
