[lxc-devel] [lxcfs/master] fixed a problem with server stability degradation caused by cgroup dy…

[yinhongbo on Github]

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From 5e0117a1c8eee3b0a844d7065de44daaaa81c4c0 Mon Sep 17 00:00:00 2001
From: Hongbo Yin <yinhongbo at bytedance.com>
Date: Wed, 9 Oct 2019 11:11:12 +0800
Subject: [PATCH] fixed a problem with server stability degradation caused by
 cgroup dying traversal.

Signed-off-by: Hongbo Yin <yinhongbo at bytedance.com>
---
 bindings.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/bindings.c b/bindings.c
index 1811955..9a5a3df 100644
--- a/bindings.c
+++ b/bindings.c
@@ -3452,6 +3452,18 @@ static int proc_meminfo_read(char *buf, size_t size, off_t offset,
 	pid_t initpid = lookup_initpid_in_store(fc->pid);
 	if (initpid <= 0)
 		initpid = fc->pid;
+
+	/*
+	 * fixed a problem with server stability degradation caused by cgroup dying traversal. This is a very bad problem.
+	 * when initpid == 1, getting meminfo will traverses all the memory cgroup.
+	 * a certain probability causes server stability to drop, such as network jitter.
+	 *
+	 * more questions about cgroup dying.
+	 * Can refer to https://lwn.net/Articles/787614/?spm=a2c4e.10696291.0.0.105919a4uX5P3F
+	 */
+	if (initpid == 1)
+		return read_file("/proc/meminfo", buf, size, d);
+
 	cg = get_pid_cgroup(initpid, "memory");
 	if (!cg)
 		return read_file("/proc/meminfo", buf, size, d);