On Tue, Feb 11, 2020 at 02:15:54PM +0000, Qais Yousef wrote: > LTP cpuset_hotplug_test.sh was failing with the following error message > > cpuset_hotplug 1 TFAIL: root group's cpus isn't expected(Result: 0-5, Expect: 0,2-5). > > Which is due to a race condition between cpu hotplug operation and > reading cpuset.cpus file. > > When a cpu is onlined/offlined, cpuset schedules a workqueue to sync its > internal data structures with the new values. If a read happens during > this window, the user will read a stale value, hence triggering the > failure above. > > To fix the issue make sure cpuset_wait_for_hotplug() is called before > allowing any value to be read, hence forcing the synchronization to > happen before the read. > > I ran 500 iterations with this fix applied with no failure triggered. > > Signed-off-by: Qais Yousef <qais.yousef@xxxxxxx> Hello, Qais. I just applied a patch which makes the operation synchronous. Can you see whether the problem is gone on the cgroup/for-next branch? git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git for-next Thanks. -- tejun
