This issue was introduced with the massive kernel configurations changes between mainline kernels 4.7-rc4 and 4.7-rc5. While I have been working on it for a couple of weeks, I was never able to isolate the exact kernel configuration change cause. I am compiling a kernel now (4.8-rc7) reverting this change to test. This attachment has some tools I made to very very simply show the issue.
If I look at linux/Documentation/workqueue.txt and do: echo workqueue:workqueue_queue_work > /sys/kernel/debug/tracing/set_event and: cat /sys/kernel/debug/tracing/trace_pipe > out.txt with the issue, I get somwhere between 10,000 and 20,000 occurances of memcg_kmem_cache_create_func in the file (using my simple test method). Without the issue, I get 21, and an overall file size about 50 times smaller, for otherwise similar conditions. i.e. with the issue this stuff seems to go nuts. ** Attachment added: "Some tools to simply show the issue" https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1626564/+attachment/4746294/+files/bla.txt -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1626564 Title: 4.8 regression: SLAB is being used instead of SLUB Status in linux package in Ubuntu: Fix Committed Status in linux source package in Yakkety: Fix Committed Bug description: We're seeing hundreds of kernel worker threads being spawned with some actions, for example, after booting the desktop and hutting the brightness keys causes this. On investigation, this occurs when CONFIG_SLAB is being used. 1. Ubuntu traditionally uses CONFIG_SLUB, so we should use that instead of CONFIG_SLAB (why was it changed for Yakkety?) 2. With CONFIG_SLUB I cannot reproduce the issue of the hundreds for worker threads 3 CONFIG_SLUB seems more performant on the boot too over SLAB. Please re-enable the CONFIG_SLUB allocator as per the 4.4. Xenial configs. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1626564/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
