[TLDR: I'm adding this regression report to the list of tracked regressions; all text from me you find below is based on a few templates paragraphs you might have encountered already already in similar form.] TWIMC: this mail is primarily send for documentation purposes and for regzbot, my Linux kernel regression tracking bot. These mails usually contain '#forregzbot' in the subject, to make them easy to spot and filter. Hi, this is your Linux kernel regression tracker. On 01.07.22 13:11, Kajetan Puchalski wrote: > Hi, > > While running the udp-flood test from stress-ng on Ampere Altra (Mt. > Jade platform) I encountered a kernel panic caused by NULL pointer > dereference within nf_conntrack. > > The issue is present in the latest mainline (5.19-rc4), latest stable > (5.18.8), as well as multiple older stable versions. The last working > stable version I found was 5.15.40. > > Through bisecting I've traced the issue back to mainline commit > 719774377622bc4025d2a74f551b5dc2158c6c30 (netfilter: conntrack: convert to refcount_t api), > on kernels from before this commit the test runs fine. As far as I can tell, this commit was > included in stable with version 5.15.41, thus causing the regression > compared to 5.15.40. It was included in the mainline with version 5.16. FWIW, looks like it was merged for v5.17-rc1 $ git describe --contains --tags 719774377622bc4025 v5.17-rc1~170^2~24^2~19 > The issue is very consistently reproducible as well, running this > command resulted in the same kernel panic every time I tried it on > different kernels from after the change in question was merged. > > stress-ng --udp-flood 0 -t 1m --metrics-brief --perf > > The commit was not easily revertible so I can't say whether reverting it > on the latest mainline would fix the problem or not. > > [...] > > The distirbution is Ubuntu 20.04.3 LTS, the architecture is aarch64. > > Please let me know if I can provide any more details or try any more > tests. Thanks for the report. To be sure below issue doesn't fall through the cracks unnoticed, I'm adding it to regzbot, my Linux kernel regression tracking bot: #regzbot ^introduced 719774377622bc402 #regzbot title net: netfilter: stress-ng udp-flood causes kernel panic on Ampere Altra This isn't a regression? This issue or a fix for it are already discussed somewhere else? It was fixed already? You want to clarify when the regression started to happen? Or point out I got the title or something else totally wrong? Then just reply -- ideally with also telling regzbot about it, as explained here: https://linux-regtracking.leemhuis.info/tracked-regression/ Reminder for developers: When fixing the issue, add 'Link:' tags pointing to the report (the mail this one replies to), as explained for in the Linux kernel's documentation; above webpage explains why this is important for tracked regressions. Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat) P.S.: As the Linux kernel's regression tracker I deal with a lot of reports and sometimes miss something important when writing mails like this. If that's the case here, don't hesitate to tell me in a public reply, it's in everyone's interest to set the public record straight.
