Hi, On 2022-08-15 16:21:51 -0400, Michael S. Tsirkin wrote: > On Mon, Aug 15, 2022 at 10:46:17AM -0700, Andres Freund wrote: > > Hi, > > > > On 2022-08-15 12:50:52 -0400, Michael S. Tsirkin wrote: > > > On Mon, Aug 15, 2022 at 09:45:03AM -0700, Andres Freund wrote: > > > > Hi, > > > > > > > > On 2022-08-15 11:40:59 -0400, Michael S. Tsirkin wrote: > > > > > OK so this gives us a quick revert as a solution for now. > > > > > Next, I would appreciate it if you just try this simple hack. > > > > > If it crashes we either have a long standing problem in virtio > > > > > code or more likely a gcp bug where it can't handle smaller > > > > > rings than what device requestes. > > > > > Thanks! > > > > > > > > I applied the below and the problem persists. > > > > > > > > [...] > > > > > > Okay! > > > > Just checking - I applied and tested this atop 6.0-rc1, correct? Or did you > > want me to test it with the 762faee5a267 reverted? I guess what you're trying > > to test if a smaller queue than what's requested you'd want to do so without > > the problematic patch applied... > > > > > > Either way, I did this, and there are no issues that I could observe. No > > oopses, no broken networking. But: > > > > To make sure it does something I added a debugging printk - which doesn't show > > up. I assume this is at a point at least earlyprintk should work (which I see > > getting enabled via serial)? > > > Sorry if I was unclear. I wanted to know whether the change somehow > exposes a driver bug or a GCP bug. So what I wanted to do is to test > this patch on top of *5.19*, not on top of the revert. Right, the 5.19 part was clear, just the earlier test: > > > > On 2022-08-15 11:40:59 -0400, Michael S. Tsirkin wrote: > > > > > OK so this gives us a quick revert as a solution for now. > > > > > Next, I would appreciate it if you just try this simple hack. > > > > > If it crashes we either have a long standing problem in virtio > > > > > code or more likely a gcp bug where it can't handle smaller > > > > > Thanks! I wasn't sure about. After I didn't see any effect on 5.19 + your patch, I grew a bit suspicious and added the printks. > Yes I think printk should work here. The reason the debug patch didn't change anything, and that my debug printk didn't show, is that gcp uses the legacy paths... If there were a bug in the legacy path, it'd explain why the problem only shows on gcp, and not in other situations. I'll queue testing the legacy path with the equivalent change. - Andres Greetings, Andres Freund _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
