Messages in this thread |  | | From | Richard Weinberger <> | Date | Mon, 2 Apr 2018 17:56:33 +0200 | Subject | Re: Question regarding container affecting the host system mounts |
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Ronak Desai,
On Mon, Apr 2, 2018 at 5:40 PM, Ronak Desai <ronak.desai@rockwellcollins.com> wrote: > I am able to workaround this issue by marking the mount as unbinadable > and clearing the flag (CL_COPY_UNBINDABLE) in "copy_tree" function in > fs/namespace.c. This skips the unbindable mounts to get cloned inside > the new namespace. For my use-case this is acceptable. > > On Thu, Mar 29, 2018 at 3:50 PM, Ronak Desai > <ronak.desai@rockwellcollins.com> wrote: >> I came across a problem where if the containers are running then it >> affects the unmount process of the system's mount points. I am not >> using these mount points as shared mounts with container. >> >> For example, I am using SD card and NAND as external storage device >> and mounting it to a mount point in the ramfs. Then I am launching >> containers and then when I try to unmount the NAND partition then my >> "unmount" call succeeds but I don't see the UBIFS hooks being called >> and because of that my UBI detach process fails. When I stopped the >> container then I see that kernel is calling the unmount as I see my >> debug prints inside the UBIFS for unmounting that partition. >> >> If I tried to mount my NAND partition once the container is up and try >> to unmount then it does unmount and detach without issue. It seems >> like there is an issue with namespace. >> >> I am using 4.1.8 kernel . I traced the kernel code and I see that >> copy_mnt_ns is calling copy_tree and which basically increasing the >> active counts of the super block of my host mount points (NAND, SD cards). >> I am using container but I do not wish to share any of my host storage >> media with >> container so in my container configuration I am only mounting the >> tmpfs as the rootfs of container is in in tmpfs of host. But, still I >> can't umount completely my host storage media if containers are >> running. >> >> I have attached the log of the container start process with debugging >> and where you can see it is increasing the super block active counts >> for "ubifs".
Not sure if I understand the problem correctly, isn't this just a matter of mount point propagation? See MS_PRIVATE.
-- Thanks, //richard
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