On 2012/10/4 15:37, Daisuke Nishimura wrote: > notify_on_release must be triggered when the last process in a cgroup is > move to another. But if the first(and only) process in a cgroup is moved to > another, notify_on_release is not triggered. > > # mkdir /cgroup/cpu/SRC > # mkdir /cgroup/cpu/DST > # > # echo 1 >/cgroup/cpu/SRC/notify_on_release > # echo 1 >/cgroup/cpu/DST/notify_on_release > # > # sleep 300 & > [1] 8629 > # > # echo 8629 >/cgroup/cpu/SRC/tasks > # echo 8629 >/cgroup/cpu/DST/tasks > -> notify_on_release for /SRC must be triggered at this point, > but it isn't. > > This is because put_css_set() is called before setting CGRP_RELEASABLE > in cgroup_task_migrate(), and is a regression introduce by the > commit:74a1166d(cgroups: make procs file writable), which was merged > into v3.0. > > Cc: Ben Blum <bblum@xxxxxxxxxxxxxx> > Cc: Tejun Heo <tj@xxxxxxxxxx> > Cc: Li Zefan <lizefan@xxxxxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> # v3.0.x and later > Signed-off-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx> > --- > This patch is based on v3.6. > > kernel/cgroup.c | 3 +-- > 1 files changed, 1 insertions(+), 2 deletions(-) > > diff --git a/kernel/cgroup.c b/kernel/cgroup.c > index 7981850..7d01182 100644 > --- a/kernel/cgroup.c > +++ b/kernel/cgroup.c > @@ -1923,9 +1923,8 @@ static void cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp, > * trading it for newcg is protected by cgroup_mutex, we're safe to drop > * it here; it will be freed under RCU. > */ > - put_css_set(oldcg); > - > set_bit(CGRP_RELEASABLE, &oldcgrp->flags); > + put_css_set(oldcg); Good catch. Also we might end up with invalid memory access! Acked-by: Li Zefan <lizefan@xxxxxxxxxx> > } > > /** > -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
