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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
This commit is contained in:
Greg Kroah-Hartman 2018-10-11 19:24:01 +02:00
parent e5337178f7 479adb89a9
commit 0778a9f2dd
2 changed files with 17 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/cgroup-defs.h
View File

@ -412,6 +412,7 @@ struct cgroup {
* specific task are charged to the dom_cgrp. * specific task are charged to the dom_cgrp.
*/ */
struct cgroup *dom_cgrp; struct cgroup *dom_cgrp;
struct cgroup *old_dom_cgrp; /* used while enabling threaded */
/* per-cpu recursive resource statistics */ /* per-cpu recursive resource statistics */
struct cgroup_rstat_cpu __percpu *rstat_cpu; struct cgroup_rstat_cpu __percpu *rstat_cpu;

25
kernel/cgroup/cgroup.c
View File

@ -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 * @cgrp: root of the target subtree
* *
* Save ->subtree_control and ->subtree_ss_mask to the respective old_ * Save ->subtree_control, ->subtree_ss_mask and ->dom_cgrp to the
* prefixed fields for @cgrp's subtree including @cgrp itself. * respective old_ prefixed fields for @cgrp's subtree including @cgrp
* itself.
*/ */
static void cgroup_save_control(struct cgroup *cgrp) 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) { cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
dsct->old_subtree_control = dsct->subtree_control; dsct->old_subtree_control = dsct->subtree_control;
dsct->old_subtree_ss_mask = dsct->subtree_ss_mask; 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 * @cgrp: root of the target subtree
* *
* Restore ->subtree_control and ->subtree_ss_mask from the respective old_ * Restore ->subtree_control, ->subtree_ss_mask and ->dom_cgrp from the
* prefixed fields for @cgrp's subtree including @cgrp itself. * respective old_ prefixed fields for @cgrp's subtree including @cgrp
* itself.
*/ */
static void cgroup_restore_control(struct cgroup *cgrp) 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) { cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
dsct->subtree_control = dsct->old_subtree_control; dsct->subtree_control = dsct->old_subtree_control;
dsct->subtree_ss_mask = dsct->old_subtree_ss_mask; 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 *parent = cgroup_parent(cgrp);
struct cgroup *dom_cgrp = parent->dom_cgrp; struct cgroup *dom_cgrp = parent->dom_cgrp;
struct cgroup *dsct;
struct cgroup_subsys_state *d_css;
int ret; int ret;
lockdep_assert_held(&cgroup_mutex); lockdep_assert_held(&cgroup_mutex);
@ -3225,12 +3231,13 @@ static int cgroup_enable_threaded(struct cgroup *cgrp)
*/ */
cgroup_save_control(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); ret = cgroup_apply_control(cgrp);
if (!ret) if (!ret)
parent->nr_threaded_children++; parent->nr_threaded_children++;
else
cgrp->dom_cgrp = cgrp;
cgroup_finalize_control(cgrp, ret); cgroup_finalize_control(cgrp, ret);
return ret; return ret;