I am seeing this problem too on my desktop PC (DP55WB with Core i5 750 processor), running 11.10. After the upgrade, the system no longer managed to resume from suspend, and would just freeze. I tried debugging the suspend; it worked until the 'platform' stage by writing to /sys/power/pm_test, but putting 'processors' would cause the system to fail to recover from suspend, so I suspected that it is an SMP related issue. I manually tried offlining a CPU, but trying to put it back online afterwards does not succeed and leads to lots of kernel errors.
The problem exists in the 3.0 kernel in oneiric, and I've even installed the 3.2-rc7 kernel from precise, but the issue remains. I'm attaching the relevant section from the syslog (The first two lines are produced after I offline CPU 3, the rest after I issue the command to bring it back online). ** Attachment added: "syslog section showing stalling of CPU core" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/907454/+attachment/2650521/+files/syslog.txt -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/907454 Title: [Dell Precision M4500] offlining and then re-onlining CPUs makes the system unresponsive To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/907454/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
