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cgroup,freezer: hold cpu_hotplug_lock before freezer_mutex in freezer_css_{online,offline}()

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syzbot is again reporting circular locking dependency between
cpu_hotplug_lock and freezer_mutex. Do like what we did with
commit 57dcd64c7e ("cgroup,freezer: hold cpu_hotplug_lock
before freezer_mutex").

Reported-by: syzbot <syzbot+2ab700fe1829880a2ec6@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=2ab700fe1829880a2ec6
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: syzbot <syzbot+2ab700fe1829880a2ec6@syzkaller.appspotmail.com>
Fixes: f5d39b0208 ("freezer,sched: Rewrite core freezer logic")
Cc: stable@vger.kernel.org # v6.1+
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tetsuo Handa
2023-06-11 22:48:12 +09:00
committed by Tejun Heo
parent 5647e53f78
commit f0cc749254
1 changed files with 6 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
kernel/cgroup/legacy_freezer.c
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@@ -108,16 +108,18 @@ static int freezer_css_online(struct cgroup_subsys_state *css)
struct freezer *freezer = css_freezer(css); struct freezer *freezer = css_freezer(css);
struct freezer *parent = parent_freezer(freezer); struct freezer *parent = parent_freezer(freezer);
cpus_read_lock();
mutex_lock(&freezer_mutex); mutex_lock(&freezer_mutex);
freezer->state |= CGROUP_FREEZER_ONLINE; freezer->state |= CGROUP_FREEZER_ONLINE;
if (parent && (parent->state & CGROUP_FREEZING)) { if (parent && (parent->state & CGROUP_FREEZING)) {
freezer->state |= CGROUP_FREEZING_PARENT | CGROUP_FROZEN; freezer->state |= CGROUP_FREEZING_PARENT | CGROUP_FROZEN;
static_branch_inc(&freezer_active); static_branch_inc_cpuslocked(&freezer_active);
} }
mutex_unlock(&freezer_mutex); mutex_unlock(&freezer_mutex);
cpus_read_unlock();
return 0; return 0;
} }
@@ -132,14 +134,16 @@ static void freezer_css_offline(struct cgroup_subsys_state *css)
{ {
struct freezer *freezer = css_freezer(css); struct freezer *freezer = css_freezer(css);
cpus_read_lock();
mutex_lock(&freezer_mutex); mutex_lock(&freezer_mutex);
if (freezer->state & CGROUP_FREEZING) if (freezer->state & CGROUP_FREEZING)
static_branch_dec(&freezer_active); static_branch_dec_cpuslocked(&freezer_active);
freezer->state = 0; freezer->state = 0;
mutex_unlock(&freezer_mutex); mutex_unlock(&freezer_mutex);
cpus_read_unlock();
} }
static void freezer_css_free(struct cgroup_subsys_state *css) static void freezer_css_free(struct cgroup_subsys_state *css)