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From: Feng Tang <feng.tang@intel.com>
To: Zefan Li <lizefan.x@bytedance.com>, Tejun Heo <tj@kernel.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Michal Hocko <mhocko@kernel.org>,
	cgroups@vger.kernel.org, linux-mm@kvack.org
Cc: Dave Hansen <dave.hansen@intel.com>,
	ying.huang@intel.com, Feng Tang <feng.tang@intel.com>
Subject: [RFC PATCH] cgroup/cpuset: fix a memory binding failure for cgroup v2
Date: Tue, 19 Apr 2022 10:09:58 +0800	[thread overview]
Message-ID: <20220419020958.40419-1-feng.tang@intel.com> (raw)

We got report that setting cpuset.mems failed when the nodemask
contains a newly onlined memory node (not enumerated during boot)
for cgroup v2, while the binding succeeded for cgroup v1.

The root cause is, for cgroup v2, when a new memory node is onlined,
top_cpuset's 'mem_allowed' is not updated with the new nodemask of
memory nodes, and the following setting memory nodemask will fail,
if the nodemask contains a new node.

Fix it by updating top_cpuset.mems_allowed right after the
new memory node is onlined, just like v1.

Signed-off-by: Feng Tang <feng.tang@intel.com>
---
Very likely I missed some details here, but it looks strange that
the top_cpuset.mem_allowed is not updatd even after we onlined
several memory nodes after boot.

 kernel/cgroup/cpuset.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 9390bfd9f1cd..b97caaf16374 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -3314,8 +3314,7 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
 	/* synchronize mems_allowed to N_MEMORY */
 	if (mems_updated) {
 		spin_lock_irq(&callback_lock);
-		if (!on_dfl)
-			top_cpuset.mems_allowed = new_mems;
+		top_cpuset.mems_allowed = new_mems;
 		top_cpuset.effective_mems = new_mems;
 		spin_unlock_irq(&callback_lock);
 		update_tasks_nodemask(&top_cpuset);
-- 
2.27.0



WARNING: multiple messages have this Message-ID (diff)
From: Feng Tang <feng.tang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
To: Zefan Li <lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>,
	Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org
Cc: Dave Hansen <dave.hansen-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	ying.huang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org,
	Feng Tang <feng.tang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Subject: [RFC PATCH] cgroup/cpuset: fix a memory binding failure for cgroup v2
Date: Tue, 19 Apr 2022 10:09:58 +0800	[thread overview]
Message-ID: <20220419020958.40419-1-feng.tang@intel.com> (raw)

We got report that setting cpuset.mems failed when the nodemask
contains a newly onlined memory node (not enumerated during boot)
for cgroup v2, while the binding succeeded for cgroup v1.

The root cause is, for cgroup v2, when a new memory node is onlined,
top_cpuset's 'mem_allowed' is not updated with the new nodemask of
memory nodes, and the following setting memory nodemask will fail,
if the nodemask contains a new node.

Fix it by updating top_cpuset.mems_allowed right after the
new memory node is onlined, just like v1.

Signed-off-by: Feng Tang <feng.tang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
Very likely I missed some details here, but it looks strange that
the top_cpuset.mem_allowed is not updatd even after we onlined
several memory nodes after boot.

 kernel/cgroup/cpuset.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 9390bfd9f1cd..b97caaf16374 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -3314,8 +3314,7 @@ static void cpuset_hotplug_workfn(struct work_struct *work)
 	/* synchronize mems_allowed to N_MEMORY */
 	if (mems_updated) {
 		spin_lock_irq(&callback_lock);
-		if (!on_dfl)
-			top_cpuset.mems_allowed = new_mems;
+		top_cpuset.mems_allowed = new_mems;
 		top_cpuset.effective_mems = new_mems;
 		spin_unlock_irq(&callback_lock);
 		update_tasks_nodemask(&top_cpuset);
-- 
2.27.0


             reply	other threads:[~2022-04-19  2:10 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-19  2:09 Feng Tang [this message]
2022-04-19  2:09 ` [RFC PATCH] cgroup/cpuset: fix a memory binding failure for cgroup v2 Feng Tang
2022-04-21 22:22 ` Tejun Heo
2022-04-21 22:22   ` Tejun Heo
2022-04-24 16:04   ` Waiman Long
2022-04-24 16:04     ` Waiman Long
2022-04-24 23:06     ` Waiman Long
2022-04-24 23:06       ` Waiman Long

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