On 16.05.22 20:22, Jens Axboe wrote: > On 5/16/22 12:17 PM, Thorsten Leemhuis wrote: >>>> Pavel, I had actually just started a draft email with the same theory >>>> (although you stated it much more clearly than I could have). I'm >>>> working on debugging the LXC side, but I'm pretty sure the issue is >>>> due to LXC using blocking reads and getting stuck exactly as you >>>> describe. If I can confirm this, I'll go ahead and mark this >>>> regression as invalid and file an issue with LXC. Thanks for your help >>>> and patience. >>> >>> Yes, it does appear that was the problem. The attach POC patch against >>> LXC fixes the hang. The kernel is working as intended. >>> >>> #regzbot invalid: userspace programming error >> >> Hmmm, not sure if I like this. So yes, this might be a bug in LXC, but >> afaics it's a bug that was exposed by kernel change in 5.17 (correct me >> if I'm wrong!). The problem thus still qualifies as a kernel regression >> that normally needs to be fixed, as can be seen my some of the quotes >> from Linus in this file: >> https://www.kernel.org/doc/html/latest/process/handling-regressions.html > > Sorry, but that's really BS in this particularly case. This could always > have triggered, it's the way multishot works. Will we count eg timing > changes as potential regressions, because an application relied on > something there? That does not make it ABI. > > In general I agree with Linus on this, a change in behavior breaking > something should be investigated and figured out (and reverted, if need > be). This is not that. Sorry, I have to deal with various subsystems and a lot of regressions reports. I can't know the details of each of issue and there are developers around that are not that familiar with all the practical implications of the "no regressions". That's why I was just trying to ensure that this is something safe to ignore. If you say it is, than I'm totally happy and now rest my case. :-D Ciao, Thorsten
