On Fri 2024-02-02 09:40:05, Paul E. McKenney wrote: > On Fri, Feb 02, 2024 at 06:56:28AM -1000, Tejun Heo wrote: > > Hello, > > > > On Fri, Feb 02, 2024 at 08:35:51AM -0800, Paul E. McKenney wrote: > > > Good point, and if this sort of thing happens frequently, perhaps there > > > should be an easy way of doing this. One crude hack that might come > > > pretty close would be to redefine the barrier() macro to be smp_mb(). > > > > > > But as noted earlier, -ENOREPRODUCE on today's -next. I will try the > > > next several -next releases. But if they all get -ENOREPRODUCE, I owe > > > everyone on CC an apology for having sent this report out before trying > > > next-20240202. :-/ > > > > I think I saw that problem too but could reproduce it with or without the > > workqueue changes, so I did the lazy thing "oh well, somebody is gonna fix > > that" and just tested as-is. It's a bit worrying that ppl don't seem to > > already know what the culprit is. Hmm... I can't reproduce it anymore > > either. > > Glad that it is not just me! I think... ;-) > > > So, there is some chance that this may really be a subtle breakage. If you > > ever see it happening again, triggering sysrq-t and capturing the dmesg > > output (network should still work fine, so these shouldn't be too difficult) > > may help. sysrq-t has workqueue state dump at the end which should clearly > > indicate if anything is stalled in workqueue. > > Good point, if it does recur, I could try it on bare metal. Please, me, John, and Sergey know if anyone see this again. I do not feel comfortable when there is problem which might make consoles calm. Well, there is no queued printk change. Also I do not see anything obvious in the changes added to 6.7 which might cause this behavior. > > That said, another data point. In my test setup, I use the earlyprintk boot > > option which enables console output way before than workqueue becomes > > operational, so having on console output at all is highly unlikely to be > > indicative of workqueue problem. My memory is hazy but it seems like I can > > no longer reproduce the problem on the same git commit. Maybe it was a > > problem on the qemu side? > > It might have been a qemu issue, but I am using the same qemu. In theory, it might also be caused by a change in the serial console driver. But I do not see anything obvious there either. Best Regards, Petr
