[PATCH 3/5] cgroup: fix mount failure in a corner case
From: Li Zefan <hidden>
Date: 2014-06-12 06:32:24
Also in:
lkml
Subsystem:
the rest · Maintainer:
Linus Torvalds
# cat test.sh #! /bin/bash mount -t cgroup -o cpu xxx /cgroup umount /cgroup mount -t cgroup -o cpu,cpuacct xxx /cgroup umount /cgroup # ./test.sh mount: xxx already mounted or /cgroup busy mount: according to mtab, xxx is already mounted on /cgroup It's because the cgroupfs_root of the first mount was under destruction asynchronously. Fix this by delaying and then retrying mount in this case. Signed-off-by: Li Zefan <redacted> --- kernel/cgroup.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 1c65f24..bd37e8d 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c@@ -1648,10 +1648,12 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, int flags, const char *unused_dev_name, void *data) { + struct cgroup_subsys *ss; struct cgroup_root *root; struct cgroup_sb_opts opts; struct dentry *dentry; int ret; + int i; bool new_sb; /*
@@ -1677,6 +1679,22 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, goto out_unlock; } + /* + * If some subsystems have been bound to existing cgroup hierarchies, + * but those hierachies are being destroyed, let's wait a little bit + * and retry. + */ + for_each_subsys(ss, i) { + if (!(opts.subsys_mask & (1 << i))) + continue; + if (!percpu_ref_alive(&ss->root->cgrp.self.refcnt)) { + mutex_unlock(&cgroup_mutex); + msleep(10); + ret = restart_syscall(); + goto out_free; + } + } + for_each_root(root) { bool name_match = false;
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1.8.0.2