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Commit 0778a9f2 authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
Browse files

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
parents e5337178 479adb89

include/linux/cgroup-defs.h

+1 −0
Original line number Diff line number Diff line
@@ -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;

kernel/cgroup/cgroup.c

+16 −9
Original line number Diff line number Diff line
@@ -2836,11 +2836,12 @@ void cgroup_lock_and_drain_offline(struct cgroup *cgrp) 
}



/**

 * 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;