Hello:
I am doing some test for kernel 6.4, util-linux version:2.39.1.
Have you encountered similar problems? If there is a fix, please
let me know.
Thank you very much
--------------------------------------------------
util-linux version 2.39.1 call mount use fsopen->fsconfig->fsmount->close
instead of mount syscall.
And use this shell test:
#!/bin/bash
mkdir -p /tmp/cgroup/cgrouptest
while true
do
mount -t cgroup -o none,name=foo cgroup /tmp/cgroup/cgrouptest
ret=$?
if [ $ret -ne 0 ];then
echo "mount failed , $ret"
fi
umount /tmp/cgroup/cgrouptest
ret=$?
if [ $ret -ne 0 ];then
echo "umount failed, $ret"
fi
done
And as a result, we mount cgroup immediately after umount, it will return
failed.
in fsconfig syscall, we find this stack:
SYSCALL_DEFINE5(fsconfig, ...)
vfs_fsconfig_locked
if (fc->phase != FS_CONTEXT_CREATE_PARAMS)
return -EBUSY;
vfs_get_tree
fc->ops->get_tree // cgroup1_get_tree
if (!ret && !percpu_ref_tryget_live
(&ctx->root->cgrp.self.refcnt))
ret = 1;
...
if (unlikely(ret > 0)) {
msleep(10);
restart_syscall();
}
...
fc->phase = FS_CONTEXT_FAILED;
in mount syscall, no function will check fs->phase, and fc is recreate
in monnt syscall. However, in fdconfig syscall, fc->phase is not initial as
FS_CONTEXT_CREATE_PARAMS, restart_syscall will return -EBUSY. fc is created
in fsopen syscall.
