[+Dmitry] On Fri, Oct 25, 2019 at 05:56:06AM -0700, Tejun Heo wrote: > On Thu, Oct 24, 2019 at 12:03:51PM -0700, Tejun Heo wrote: > > cgroup_enable_task_cg_lists() is used to lazyily initialize task > > cgroup associations on the first use to reduce fork / exit overheads > > on systems which don't use cgroup. Unfortunately, locking around it > > has never been actually correct and its value is dubious given how the > > vast majority of systems use cgroup right away from boot. > > > > This patch removes the optimization. For now, replace the cg_list > > based branches with WARN_ON_ONCE()'s to be on the safe side. We can > > simplify the logic further in the future. > > > > Signed-off-by: Tejun Heo <tj@xxxxxxxxxx> > > Reported-by: Oleg Nesterov <oleg@xxxxxxxxxx> > > Applying to cgroup/for-5.5. The code you removed was the only place where task->flags was set from !current. So I think this fixes the syzbot data-race report in: https://lore.kernel.org/r/0000000000003b1e8005956939f1@xxxxxxxxxx Link: syzbot+492a4acccd8fc75ddfd0@xxxxxxxxxxxxxxxxxxxxxxxxx Thanks! Christian
