[PATCH OLK-5.10 0/2] Backport cgroup: fix missing cpus_read_{lock,unlock}() in cgroup_transfer_tasks()
Backport cgroup: fix missing cpus_read_{lock,unlock}() in cgroup_transfer_tasks() and cgroup: Use cgroup_attach_{lock,unlock}() from cgroup_attach_task_all()
Qi Zheng (1): cgroup: fix missing cpus_read_{lock,unlock}() in cgroup_transfer_tasks()
Tetsuo Handa (1): cgroup: Use cgroup_attach_{lock,unlock}() from cgroup_attach_task_all()
kernel/cgroup/cgroup-internal.h | 2 ++ kernel/cgroup/cgroup-v1.c | 10 ++++------ kernel/cgroup/cgroup.c | 4 ++-- 3 files changed, 8 insertions(+), 8 deletions(-)
From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp
mainline inclusion from mainline-v6.1-rc1 commit 075b593f54f0f3883532cb750081cae6917bc8fe category: cleanup bugzilla: 189018, https://gitee.com/openeuler/kernel/issues/I7RPDX
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
--------------------------------
No behavior changes; preparing for potential locking changes in future.
Signed-off-by: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Reviewed-by:Mukesh Ojha quic_mojha@quicinc.com Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Cai Xinchen caixinchen1@huawei.com --- kernel/cgroup/cgroup-internal.h | 2 ++ kernel/cgroup/cgroup-v1.c | 6 ++---- kernel/cgroup/cgroup.c | 4 ++-- 3 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h index 3f116765bb00..6fc71b98209e 100644 --- a/kernel/cgroup/cgroup-internal.h +++ b/kernel/cgroup/cgroup-internal.h @@ -250,6 +250,8 @@ int cgroup_migrate(struct task_struct *leader, bool threadgroup,
int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader, bool threadgroup); +void cgroup_attach_lock(bool lock_threadgroup); +void cgroup_attach_unlock(bool lock_threadgroup); struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup, bool *locked) __acquires(&cgroup_threadgroup_rwsem); diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index 647d0891cff6..d7e2d232acc4 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -57,8 +57,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) int retval = 0;
mutex_lock(&cgroup_mutex); - cpus_read_lock(); - percpu_down_write(&cgroup_threadgroup_rwsem); + cgroup_attach_lock(true); for_each_root(root) { struct cgroup *from_cgrp;
@@ -73,8 +72,7 @@ int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) if (retval) break; } - percpu_up_write(&cgroup_threadgroup_rwsem); - cpus_read_unlock(); + cgroup_attach_unlock(true); mutex_unlock(&cgroup_mutex);
return retval; diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index d0a4a1c4c38d..2bc5bae49d20 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -2367,7 +2367,7 @@ EXPORT_SYMBOL_GPL(task_cgroup_path); * write-locking cgroup_threadgroup_rwsem. This allows ->attach() to assume that * CPU hotplug is disabled on entry. */ -static void cgroup_attach_lock(bool lock_threadgroup) +void cgroup_attach_lock(bool lock_threadgroup) { cpus_read_lock(); if (lock_threadgroup) @@ -2378,7 +2378,7 @@ static void cgroup_attach_lock(bool lock_threadgroup) * cgroup_attach_unlock - Undo cgroup_attach_lock() * @lock_threadgroup: whether to up_write cgroup_threadgroup_rwsem */ -static void cgroup_attach_unlock(bool lock_threadgroup) +void cgroup_attach_unlock(bool lock_threadgroup) { if (lock_threadgroup) percpu_up_write(&cgroup_threadgroup_rwsem);
From: Qi Zheng zhengqi.arch@bytedance.com
mainline inclusion from mainline-v6.4-rc6 commit ab1de7ead871ebe6d12a774c3c25de0388cde082 category: bugfix bugzilla: 189018, https://gitee.com/openeuler/kernel/issues/I7RPDX
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
--------------------------------
The commit 4f7e7236435c ("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock") fixed the deadlock between cgroup_threadgroup_rwsem and cpus_read_lock() by introducing cgroup_attach_{lock,unlock}() and removing cpus_read_{lock,unlock}() from cpuset_attach(). But cgroup_transfer_tasks() was missed and not handled, which will cause th following warning:
WARNING: CPU: 0 PID: 589 at kernel/cpu.c:526 lockdep_assert_cpus_held+0x32/0x40 CPU: 0 PID: 589 Comm: kworker/1:4 Not tainted 6.4.0-rc2-next-20230517 #50 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 Workqueue: events cpuset_hotplug_workfn RIP: 0010:lockdep_assert_cpus_held+0x32/0x40 <...> Call Trace: <TASK> cpuset_attach+0x40/0x240 cgroup_migrate_execute+0x452/0x5e0 ? _raw_spin_unlock_irq+0x28/0x40 cgroup_transfer_tasks+0x1f3/0x360 ? find_held_lock+0x32/0x90 ? cpuset_hotplug_workfn+0xc81/0xed0 cpuset_hotplug_workfn+0xcb1/0xed0 ? process_one_work+0x248/0x5b0 process_one_work+0x2b9/0x5b0 worker_thread+0x56/0x3b0 ? process_one_work+0x5b0/0x5b0 kthread+0xf1/0x120 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x1f/0x30 </TASK>
So just use the cgroup_attach_{lock,unlock}() helper to fix it.
Reported-by: Zhao Gongyi zhaogongyi@bytedance.com Signed-off-by: Qi Zheng zhengqi.arch@bytedance.com Acked-by: Muchun Song songmuchun@bytedance.com Fixes: 05c7b7a92cc8 ("cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug") Cc: stable@vger.kernel.org # v5.17+ Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Cai Xinchen caixinchen1@huawei.com --- kernel/cgroup/cgroup-v1.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index d7e2d232acc4..b913923497e9 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -107,7 +107,7 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
mutex_lock(&cgroup_mutex);
- percpu_down_write(&cgroup_threadgroup_rwsem); + cgroup_attach_lock(true);
/* all tasks in @from are being moved, all csets are source */ spin_lock_irq(&css_set_lock); @@ -143,7 +143,7 @@ int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) } while (task && !ret); out_err: cgroup_migrate_finish(&mgctx); - percpu_up_write(&cgroup_threadgroup_rwsem); + cgroup_attach_unlock(true); mutex_unlock(&cgroup_mutex); return ret; }
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