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If so, there wouldn't be any need to touch this > > message. > > Hi Ido, > > Thanks for looking into this! > > Correct me if I'm misunderstanding the code comment above that check: > > /* > * If the address was optimistic we inserted the route at the > * start of our DAD process, so we don't need to do it again. > * If the device was taken down in the middle of the DAD > * cycle there is a race where we could get here without a > * host route, so nothing to insert. That will be fixed when > * the device is brought up. > */ > > It seems this state is somewhat expected/handled and otherwise > harmless. The main issue here is simply that pr_warn() includes the > literal string "BUG: ", which leads syzkaller to treat a non-fatal > warning as a critical kernel panic/crash. The comment refers to the case where the device is down, but the warning fires when the device is up. According to the blamed commit, the state where the warning fires should be impossible to reach: "Add a warning if the host route is missing AND the device is up; this is a situation that should never happen". I guess that is why "BUG: " was used. I have a reproducer that always ends up in this state, so it's not impossible to reach. I need to see if we can avoid ending up in this state, and then it should be fine to keep the message since it should never fire unless there's an actual bug.