On Thu, Dec 12, 2013 at 10:34:18AM -0600, Chris J Arges wrote: > Hi stable maintainers, > > Please consider the following commit for 3.2-3.12 kernels: > > commit f9f9ffc237dd924f048204e8799da74f9ecf40cf > Author: Ben Segall <bsegall@xxxxxxxxxx> > Date: Wed Oct 16 11:16:32 2013 -0700 > > sched: Avoid throttle_cfs_rq() racing with period_timer stopping > > throttle_cfs_rq() doesn't check to make sure that period_timer is > running, > and while update_curr/assign_cfs_runtime does, a concurrently running > period_timer on another cpu could cancel itself between this cpu's > update_curr and throttle_cfs_rq(). If there are no other cfs_rqs > running > in the tg to restart the timer, this causes the cfs_rq to be stranded > forever. > > Fix this by calling __start_cfs_bandwidth() in throttle if the timer is > inactive. > > (Also add some sched_debug lines for cfs_bandwidth.) > > Tested: make a run/sleep task in a cgroup, loop switching the cgroup > between 1ms/100ms quota and unlimited, checking for timer_active=0 and > throttled=1 as a failure. With the throttle_cfs_rq() change > commented out > this fails, with the full patch it passes. > > Signed-off-by: Ben Segall <bsegall@xxxxxxxxxx> > Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: pjt@xxxxxxxxxx > Link: > http://lkml.kernel.org/r/20131016181632.22647.84174.stgit@xxxxxxxxxxxxxxxxxxxxx. > Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> > > > A bug was noticed when running VMs and setting cpu.cfs_quota for that > vcpu's cpu cgroup. Occasionally when rebooting or shutting down a VM the > vcpu task would get stuck in a state where the task has a timer disabled > and no longer gets scheduled on the cfs_rq. This patch fixes > throttle_cfs_rq by checking if the timer is not active, and then calling > __start_cfs_bandwidth. > > I have only built this against 3.2, 3.5, 3.8 and 3.11. 3.2 and 3.5 > required trivial backports. While, 3.8/3.11 were clean cherry-picks. For 3.4, this breaks the build, care to provide a "buildable" backport for that kernel version? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html