We should not keep @css_set_lock spinlock while removing group files which leads to
| BUG: sleeping function called from invalid context at kernel/locking/mutex.c:938 This is because cgroup_rm_file() function takes @kernfs_mutex itself. Since we're keeping the reference to cset in VE itself we don't even need to take spinlock at all, because cset won't disappear until last put_ve() call. https://jira.sw.ru/browse/PSBM-135460 Signed-off-by: Cyrill Gorcunov <gorcu...@gmail.com> --- kernel/cgroup/cgroup.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) Index: vzkernel/kernel/cgroup/cgroup.c =================================================================== --- vzkernel.orig/kernel/cgroup/cgroup.c +++ vzkernel/kernel/cgroup/cgroup.c @@ -2152,9 +2152,9 @@ void cgroup_unmark_ve_roots(struct ve_st struct cftype *cft; cft = get_cftype_by_name(CGROUP_FILENAME_RELEASE_AGENT); + BUG_ON(!cft || cft->file_offset); mutex_lock(&cgroup_mutex); - spin_lock_irq(&css_set_lock); /* * We can safely use ve->ve_ns without rcu_read_lock here, as we are @@ -2163,19 +2163,26 @@ void cgroup_unmark_ve_roots(struct ve_st */ cset = rcu_dereference_protected(ve->ve_ns, lockdep_is_held(&ve->op_sem))->cgroup_ns->root_cset; + BUG_ON(!cset); + /* + * Traversing @cgrp_links without @css_set_lock is safe here because + * we ourself are keeping the reference to the @cset so it won't + * disappear until the last reference get dropped upon ve destruction + * via put_ve() call. + */ list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { cgrp = link->cgrp; if (!is_virtualized_cgroup(cgrp)) continue; - cgroup_rm_file(cgrp, cft); + if (!cgroup_is_dead(cgrp)) + cgroup_rm_file(cgrp, cft); rcu_assign_pointer(cgrp->ve_owner, NULL); clear_bit(CGRP_VE_ROOT, &cgrp->flags); } - spin_unlock_irq(&css_set_lock); mutex_unlock(&cgroup_mutex); /* ve_owner == NULL will be visible */ synchronize_rcu(); _______________________________________________ Devel mailing list Devel@openvz.org https://lists.openvz.org/mailman/listinfo/devel
