From ac2b5c94f26e408022b010c33e1479753fb0f91f Mon Sep 17 00:00:00 2001
From: zhongjiang-ali <zhongjiang-ali@linux.alibaba.com>
Date: Wed, 26 Feb 2020 12:25:11 +0800
Subject: [PATCH] alinux: kernel: reap zombie process by specified pid
to #26788859
We've met several real-world issues that the child reaper
(i.e. systemd) gets stuck in some aborted status and cann't
reap its zombie children, so we provide the interface to do
By specified the pid.
Reviewed-by: Xunlei Pang <xlpang@linux.alibaba.com>
Signed-off-by: zhongjiang-ali <zhongjiang-ali@linux.alibaba.com>
---
kernel/exit.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 110 insertions(+)
diff --git a/kernel/exit.c b/kernel/exit.c
index 449bc7bbfda3..c536da853873 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1765,3 +1765,113 @@ __weak void abort(void)
panic("Oops failed to kill thread");
}
EXPORT_SYMBOL(abort);
+
+static int force_reap_process(int ptrace, struct task_struct *tsk)
+{
+ struct wait_opts wo;
+ struct pid *pid = get_task_pid(tsk, PIDTYPE_PID);
+ int ret;
+
+ memset(&wo, 0, sizeof(wo));
+ wo.wo_type = PIDTYPE_PID;
+ wo.wo_pid = pid;
+ wo.wo_flags = WEXITED;
+
+ ret = wait_consider_task(&wo, ptrace, tsk);
+ put_pid(pid);
+
+ return ret;
+}
+
+
+static void exit_zombie_process(struct task_struct *tsk)
+{
+ int ret;
+
+ read_lock(&tasklist_lock);
+ ret = force_reap_process(0, tsk);
+ if (ret)
+ goto out;
+ read_unlock(&tasklist_lock);
+out:
+ return;
+}
+
+extern int pid_max;
+#define LEN 8
+static ssize_t reclaim_zombie_process_write(struct file *file,
+ const char __user *ubuf,
+ size_t count, loff_t *ppos)
+{
+ int ret;
+ unsigned int pid;
+ struct task_struct *tsk;
+ char buf[LEN];
+
+ memset(buf, 0, LEN);
+ if (count > LEN - 1) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ if (copy_from_user(buf, ubuf, count)) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ ret = kstrtoint(strstrip(buf), 10, &pid);
+ if (ret)
+ goto out;
+
+ if (pid > pid_max) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /* make sure the task status is zombie. */
+ rcu_read_lock();
+ tsk = find_task_by_pid_ns(pid, task_active_pid_ns(current));
+ if (tsk) {
+ get_task_struct(tsk);
+ if (READ_ONCE(tsk->exit_state) != EXIT_ZOMBIE) {
+ rcu_read_unlock();
+ put_task_struct(tsk);
+ ret = -EINVAL;
+ goto out;
+ }
+ } else {
+ rcu_read_unlock();
+ ret = -EINVAL;
+ goto out;
+ }
+ rcu_read_unlock();
+ exit_zombie_process(tsk);
+ put_task_struct(tsk);
+out:
+ return ret == 0 ? count : ret;
+}
+
+const struct file_operations reclaim_zombie_process_fops = {
+ .owner = THIS_MODULE,
+ .llseek = noop_llseek,
+ .write = reclaim_zombie_process_write,
+};
+
+static int __init reclaim_zombie_process_init(void)
+{
+ struct proc_dir_entry *rzp_dir, *rzp_file;
+
+ rzp_dir = proc_mkdir("toolkit", NULL);
+ if (!rzp_dir)
+ return -ENOMEM;
+
+ rzp_file = proc_create("reclaim_zombie_process", 0200, rzp_dir,
+ &reclaim_zombie_process_fops);
+ if (!rzp_file) {
+ remove_proc_entry("toolkit", NULL);
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+late_initcall(reclaim_zombie_process_init);
--
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