Bug 1757845
| Summary: | You have to remove that container to be able to reuse that name.: that name is already in use (due to exec user process caused "no such file or directory") | |||
|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 8 | Reporter: | Michele Baldessari <michele> | |
| Component: | podman | Assignee: | Nalin Dahyabhai <nalin> | |
| Status: | CLOSED ERRATA | QA Contact: | atomic-bugs <atomic-bugs> | |
| Severity: | high | Docs Contact: | ||
| Priority: | unspecified | |||
| Version: | 8.1 | CC: | bbaude, bdobreli, dciabrin, ddarrah, dmaley, dornelas, dwalsh, elicohen, emacchi, gscrivan, jligon, jnovy, lmiccini, lsm5, mheon, mschuppe, nalin, psahoo, pthomas, toneata, tsweeney, weshen | |
| Target Milestone: | rc | Keywords: | ZStream | |
| Target Release: | 8.2 | |||
| Hardware: | Unspecified | |||
| OS: | Unspecified | |||
| Whiteboard: | ||||
| Fixed In Version: | podman-1.6.4-2.el8 | Doc Type: | If docs needed, set a value | |
| Doc Text: | Story Points: | --- | ||
| Clone Of: | ||||
| : | 1787524 (view as bug list) | Environment: | ||
| Last Closed: | 2020-04-28 15:47:44 UTC | Type: | Bug | |
| Regression: | --- | Mount Type: | --- | |
| Documentation: | --- | CRM: | ||
| Verified Versions: | Category: | --- | ||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | ||
| Cloudforms Team: | --- | Target Upstream Version: | ||
| Embargoed: | ||||
| Bug Depends On: | ||||
| Bug Blocks: | 1727325, 1734579, 1787524 | |||
*** Bug 1766337 has been marked as a duplicate of this bug. *** I don't think my proposed fix is enough. I see other potential races with the home directory.
I think we still need to make sure there is no cleanup happening between a home directory mount and the overlay mount created on top of it. My guess is that we hit the issue when something similar happens:
Process A Process B Process C
-----> mount home directory? Yes, it is not there
-----> mount overlay
-----> run container
-----> umount overlay
--------------------------------------------------> mount home directory? No, it is already mounted
-----> umount home directory? Yes, there are no mounts
--------------------------------------------------> mount overlay (directly on the host, no home directory present)
---------------------------------------------------------------------------------------------------------> mount home directory? Yes, it is not there (shadow mount overlay B)
--------------------------------------------------> run container
--------------------------------------------------> umount overlay
Now depending at what time process B is, the mount home directory from process C can cause different sort of issues. If it is already inside of runc between prepareRoot() and "unix.Mount("", "/", "", uintptr(flag), "")" then it will cause the issue observed above with "exec user process caused "no such file or directory")". When process B terminates it is unable to cleanup the overlay mount as it is not accessible.
Potential fixes:
- In store.Mount() we already have a lock on rlstore: is it enough to make sure the home directory exists before the mount or are there other cases where the overlay can be created?
- drop the home directory completely. The performance benefit we have is probably outweighed by the locking.
- never drop the home directory mount. We leak a mount when there are no containers running, but both performance benefit and no extra locking
I think the safest thing would be to just leak. Then if someone wants to remove it they could manually umount it. while working on it, I saw we are already using the lock as part of the mount operation so we just need to keep it a bit longer. Given that, I've opted for the first option instead and opened a PR. Marked as WIP as it needs more testing: https://github.com/containers/storage/pull/497 Thanks a bunch, Giuseppe. I'll take this PR for a long spin and report back (FWIW I left the first patch at c#51 running for 36 straight hours on three vms and it worked without issues. I'll do the same for this one and update here either over the weekend or on Monday) thanks, so the PR I've opened also includes the fix you were testing and in addition to that, we hold the lock also during the mount itself. I am still looking at it today, I'll let you know when it is ready for testing. Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHSA-2020:1650 |
Strange man 2 umount ,,, EINVAL target is not a mount point. EINVAL umount2() was called with MNT_EXPIRE and either MNT_DETACH or MNT_FORCE. EINVAL (since Linux 2.6.34) umount2() was called with an invalid flag value in flags. man 3 unlink ... EBUSY The file pathname cannot be unlinked because it is being used by the system or another process; for example, it is a mount point or the NFS client software created it to represent an active but otherwise nameless inode ("NFS silly renamed"). This looks like something in stroage is complaining about merged not being mounted and later an attempt is made to remove the file and it says that it can't because something is mounte don it.