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commit 0778a9f2dd924c3af41971ba40eec44793aea531
parent e5337178f7023bd06a39c06e1fab88817559c0f3
Author: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date:   Thu, 11 Oct 2018 19:24:01 +0200

Merge branch 'for-4.19-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Tejun writes:
  "cgroup fixes for v4.19-rc7

   One cgroup2 threaded mode fix for v4.19-rc7.  While threaded mode
   isn't used widely (yet) and the bug requires somewhat convoluted
   sequence of operations, it causes a userland visible malfunction -
   EINVAL on a valid attempt to enable threaded mode.  This pull request
   contains the fix"

* 'for-4.19-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: Fix dom_cgrp propagation when enabling threaded mode

Diffstat:
Minclude/linux/cgroup-defs.h | 1+
Mkernel/cgroup/cgroup.c | 25++++++++++++++++---------
2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h @@ -412,6 +412,7 @@ struct cgroup { * specific task are charged to the dom_cgrp. */ struct cgroup *dom_cgrp; + struct cgroup *old_dom_cgrp; /* used while enabling threaded */ /* per-cpu recursive resource statistics */ struct cgroup_rstat_cpu __percpu *rstat_cpu; diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c @@ -2836,11 +2836,12 @@ restart: } /** - * cgroup_save_control - save control masks of a subtree + * cgroup_save_control - save control masks and dom_cgrp of a subtree * @cgrp: root of the target subtree * - * Save ->subtree_control and ->subtree_ss_mask to the respective old_ - * prefixed fields for @cgrp's subtree including @cgrp itself. + * Save ->subtree_control, ->subtree_ss_mask and ->dom_cgrp to the + * respective old_ prefixed fields for @cgrp's subtree including @cgrp + * itself. */ static void cgroup_save_control(struct cgroup *cgrp) { @@ -2850,6 +2851,7 @@ static void cgroup_save_control(struct cgroup *cgrp) cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { dsct->old_subtree_control = dsct->subtree_control; dsct->old_subtree_ss_mask = dsct->subtree_ss_mask; + dsct->old_dom_cgrp = dsct->dom_cgrp; } } @@ -2875,11 +2877,12 @@ static void cgroup_propagate_control(struct cgroup *cgrp) } /** - * cgroup_restore_control - restore control masks of a subtree + * cgroup_restore_control - restore control masks and dom_cgrp of a subtree * @cgrp: root of the target subtree * - * Restore ->subtree_control and ->subtree_ss_mask from the respective old_ - * prefixed fields for @cgrp's subtree including @cgrp itself. + * Restore ->subtree_control, ->subtree_ss_mask and ->dom_cgrp from the + * respective old_ prefixed fields for @cgrp's subtree including @cgrp + * itself. */ static void cgroup_restore_control(struct cgroup *cgrp) { @@ -2889,6 +2892,7 @@ static void cgroup_restore_control(struct cgroup *cgrp) cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) { dsct->subtree_control = dsct->old_subtree_control; dsct->subtree_ss_mask = dsct->old_subtree_ss_mask; + dsct->dom_cgrp = dsct->old_dom_cgrp; } } @@ -3196,6 +3200,8 @@ static int cgroup_enable_threaded(struct cgroup *cgrp) { struct cgroup *parent = cgroup_parent(cgrp); struct cgroup *dom_cgrp = parent->dom_cgrp; + struct cgroup *dsct; + struct cgroup_subsys_state *d_css; int ret; lockdep_assert_held(&cgroup_mutex); @@ -3225,12 +3231,13 @@ static int cgroup_enable_threaded(struct cgroup *cgrp) */ cgroup_save_control(cgrp); - cgrp->dom_cgrp = dom_cgrp; + cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) + if (dsct == cgrp || cgroup_is_threaded(dsct)) + dsct->dom_cgrp = dom_cgrp; + ret = cgroup_apply_control(cgrp); if (!ret) parent->nr_threaded_children++; - else - cgrp->dom_cgrp = cgrp; cgroup_finalize_control(cgrp, ret); return ret;