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.
On Fri, Sep 22, 2023 at 10:18:24AM +0800, Cai Xinchen wrote:
> 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
> 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.
Mount api system calls aren't restartable so that doesn't work. cgroup2
doesn't have this issue, only cgroup1 has. So cgroup1_get_tree() should
probably be fixed if anyone cares.
On Fri, 22 Sep 2023 10:08:36 +0200
Christian Brauner <[email protected]> wrote:
> On Fri, Sep 22, 2023 at 10:18:24AM +0800, Cai Xinchen wrote:
> > 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
>
>
> > 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.
>
> Mount api system calls aren't restartable so that doesn't work. cgroup2
> doesn't have this issue, only cgroup1 has. So cgroup1_get_tree() should
> probably be fixed if anyone cares.
>
Dear colleagues,
I've met the same issue a few years ago and tried to fix it:
https://lore.kernel.org/all/[email protected]/
but didn't come into agreement about this.
Kind regards,
Alex