[ovirt-devel] Re: [VDSM] TestMount.testSymlinkMount failing

On Mon, Nov 12, 2018 at 7:03 AM Germano Veit Michel <germano(a)redhat.com&gt; wrote: > > > On Fri, Nov 9, 2018 at 3:25 PM Germano Veit Michel <germano(a)redhat.com&gt; > wrote: > >> >> >> On Wed, Nov 7, 2018 at 9:34 PM Nir Soffer <nsoffer(a)redhat.com&gt; wrote: >> >>> On Wed, Nov 7, 2018 at 6:27 AM Germano Veit Michel <germano(a)redhat.com&gt; >>> wrote: >>> >>>> Hi, >>>> >>>> I have seen CI failing with some "random" errors which makes >>>> submitting a series of patches a bit annoying, as some patch always fails >>>> with some error, then next run another patch fails. >>>> >>>> One of these problems is TestMount.testSymlinkMount. Looks like its >>>> getting EBUSY when doing a rmdir. So probably something still using it? >>>> >>>> =================================== FAILURES =================================== >>>> __________________________ TestMount.testSymlinkMount __________________________ >>>> >>>> args = (<storage.mount_test.TestMount testMethod=testSymlinkMount>,) >>>> kwargs = {} >>>> >>>> @wraps(f) >>>> def wrapper(*args, **kwargs): >>>> if cond: >>>> raise SkipTest(reason) >>>> > return f(*args, **kwargs) >>>> >>>> testValidation.py:274: >>>> _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ >>>> testValidation.py:333: in wrapper >>>> return f(*args, **kwargs) >>>> storage/mount_test.py:167: in testSymlinkMount >>>> m.umount() >>>> /usr/lib64/python2.7/contextlib.py:35: in __exit__ >>>> self.gen.throw(type, value, traceback) >>>> testlib.py:218: in namedTemporaryDir >>>> shutil.rmtree(tmpDir) >>>> /usr/lib64/python2.7/shutil.py:261: in rmtree >>>> rmtree(fullname, ignore_errors, onerror) >>>> /usr/lib64/python2.7/shutil.py:270: in rmtree >>>> onerror(os.rmdir, path, sys.exc_info()) >>>> _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ >>>> >>>> path = '/var/tmp/tmpOYMiHx/mountpoint', ignore_errors = False >>>> onerror = <function onerror at 0x7fd68afc9938> >>>> >>>> def rmtree(path, ignore_errors=False, onerror=None): >>>> """Recursively delete a directory tree. >>>> >>>> If ignore_errors is set, errors are ignored; otherwise, if onerror >>>> is set, it is called to handle the error with arguments (func, >>>> path, exc_info) where func is os.listdir, os.remove, or os.rmdir; >>>> path is the argument to that function that caused it to fail; and >>>> exc_info is a tuple returned by sys.exc_info(). If ignore_errors >>>> is false and onerror is None, an exception is raised. >>>> >>>> """ >>>> if ignore_errors: >>>> def onerror(*args): >>>> pass >>>> elif onerror is None: >>>> def onerror(*args): >>>> raise >>>> try: >>>> if os.path.islink(path): >>>> # symlinks to directories are forbidden, see bug #1669 >>>> raise OSError("Cannot call rmtree on a symbolic link") >>>> except OSError: >>>> onerror(os.path.islink, path, sys.exc_info()) >>>> # can't continue even if onerror hook returns >>>> return >>>> names = [] >>>> try: >>>> names = os.listdir(path) >>>> except os.error, err: >>>> onerror(os.listdir, path, sys.exc_info()) >>>> for name in names: >>>> fullname = os.path.join(path, name) >>>> try: >>>> mode = os.lstat(fullname).st_mode >>>> except os.error: >>>> mode = 0 >>>> if stat.S_ISDIR(mode): >>>> rmtree(fullname, ignore_errors, onerror) >>>> else: >>>> try: >>>> os.remove(fullname) >>>> except os.error, err: >>>> onerror(os.remove, fullname, sys.exc_info()) >>>> try: >>>> > os.rmdir(path) >>>> E OSError: [Errno 16] Device or resource busy: '/var/tmp/tmpOYMiHx/mountpoint' >>>> >>>> /usr/lib64/python2.7/shutil.py:268: OSError >>>> ----------------------------- Captured stderr call ----------------------------- >>>> 2018-11-07 00:41:55,518 DEBUG (MainThread) [storage.Misc.excCmd] /usr/bin/taskset --cpu-list 0-1 /sbin/mkfs.ext2 -F /var/tmp/tmpOYMiHx/backing.img (cwd None) (commands:68) >>>> 2018-11-07 00:41:55,561 DEBUG (MainThread) [storage.Misc.excCmd] SUCCESS: <err> = 'mke2fs 1.44.2 (14-May-2018)\n'; <rc> = 0 (commands:89) >>>> 2018-11-07 00:41:55,562 INFO (MainThread) [storage.Mount] mounting /var/tmp/tmpOYMiHx/link_to_image at /var/tmp/tmpOYMiHx/mountpoint (mount:204) >>>> 2018-11-07 00:41:55,563 DEBUG (MainThread) [root] /usr/bin/taskset --cpu-list 0-1 /usr/bin/mount -o loop /var/tmp/tmpOYMiHx/link_to_image /var/tmp/tmpOYMiHx/mountpoint (cwd None) (commands:68) >>>> 2018-11-07 00:41:55,598 DEBUG (MainThread) [root] SUCCESS: <err> = ''; <rc> = 0 (commands:89) >>>> 2018-11-07 00:41:55,599 DEBUG (MainThread) [storage.Mount] /var/tmp/tmpOYMiHx/mountpoint mounted: 0.03 seconds (utils:454) >>>> 2018-11-07 00:41:55,599 DEBUG (MainThread) [root] /usr/bin/taskset --cpu-list 0-1 /sbin/udevadm settle --timeout=5 (cwd None) (commands:68) >>>> 2018-11-07 00:41:55,624 DEBUG (MainThread) [root] SUCCESS: <err> = ''; <rc> = 0 (commands:89) >>>> 2018-11-07 00:41:55,625 DEBUG (MainThread) [storage.Mount] Waiting for udev mount events: 0.03 seconds (utils:454) >>>> 2018-11-07 00:41:55,628 INFO (MainThread) [storage.Mount] unmounting /var/tmp/tmpOYMiHx/mountpoint (mount:212) >>>> 2018-11-07 00:41:55,629 DEBUG (MainThread) [root] /usr/bin/taskset --cpu-list 0-1 /usr/bin/umount /var/tmp/tmpOYMiHx/mountpoint (cwd None) (commands:68) >>>> 2018-11-07 00:41:55,658 DEBUG (MainThread) [root] FAILED: <err> = 'umount: /var/tmp/tmpOYMiHx/mountpoint: target is busy.\n'; <rc> = 32 (commands:89) >>>> >>>> >>> The test is doing: >>> >>> 163 m.mount(mntOpts="loop") >>> 164 try: >>> 165 self.assertTrue(m.isMounted()) >>> 166 finally: >>> 167 m.umount() >>> >>> So nothing can use this mount - except systemd, creating a mount unit >>> for every mount >>> created by "mount". >>> >>> If you can reproduce this with calling "mount" and "umount" in a loop, >>> we can open >>> a systemd bug for this. >>> >>> Adding little sleep before unmounting will probably avoid this issue. >>> In production we >>> never unmount write after mount. >>> >>> A possible fix is to use m.umount(force=True, lazy=True) - this is how >>> we unmount >>> file based storage mounts in lib/vdsm/storage/storageServer.py: >>> >>> 201 def disconnect(self): >>> 202 self._mount.umount(True, True) >>> >>> Nir >>> >> >> Thanks Nir! >> >> I'll see if I can reproduce it next week. I have only seen this one on >> FC28, so it could be a FC28 bug. >> Yesterday the rebase CI also failed on 2 patches, but the errors were >> different and I did not have time to investigate. >> > > Hit it again, but now on testLoopMount() instead of testSymlinkMount(). > > Tried reproducing it on F29 (not 28), did not hit it. > > #!/bin/bash > > truncate -s 100M /tmp/a > mkfs.ext2 /tmp/a > mkdir /tmp/b > while [ True ] > do > mount -o loop /tmp/a /tmp/b > umount /tmp/b > done > > Do you want me to submit a patch with m.umount(force=True, lazy=True) for > all those tests? Would it be correct to do this? > I reproduce these issue today in the CI, and look at git history. We had force=True in the past, but it was removed in: commit c8a216677e82aa61aab0c98a1021265121f8db57 Author: Nir Soffer <nsoffer(a)redhat.com&gt; Date: Sun Apr 24 01:05:33 2016 +0300 mount: Remove pointless force=True usage Using force=True when unmounting loop device is pointless - this option will cause umount(8) to call the umount(2) syscall with the MNT_FORCE flag, which is useful only for NFS mounts. Change-Id: I31ff97d882f292f9c6325903ed9072b7146f682e Signed-off-by: Nir Soffer <nsoffer(a)redhat.com&gt; Reviewed-on: https://gerrit.ovirt.org/56524 Reviewed-by: Dan Kenigsberg <danken(a)redhat.com&gt; Reviewed-by: Allon Mureinik <amureini(a)redhat.com&gt; Continuous-Integration: Jenkins CI We fixed similar issue later in: commit d158b1a6f54ba67d81cb163593e3c330c77d36fd Author: Nir Soffer <nsoffer(a)redhat.com&gt; Date: Sun Apr 24 22:36:47 2016 +0300 mount: Wait for systemd temporary mount unit Systemd is monitoring mountpoints created during runtime by creating a temporary mount units. For example: # systemctl status /tmp/mount-1.DUNxySxI2R/wrk ● tmp-mount\x2d1.DUNxySxI2R-wrk.mount - /tmp/mount-1.DUNxySxI2R/wrk Loaded: loaded (/proc/self/mountinfo) Active: active (mounted) since Sun 2016-04-24 22:37:55 IDT; 14ms ago Where: /tmp/mount-1.DUNxySxI2R/wrk What: /dev/loop2 Mounting and unmounting quickly as we do in the tests, or when creating a floppy image may confuse systemd, and lead to various errors: - mountpoint is not mounted when trying to access files or unmount - mountpoint is busy when trying to unmount These are probably systemd or mount bugs. Until these issues are resolve, we need to find a workaround to avoid failures in the tests or when creating a floppy images. This patch add udevadm.settle() call after successful mount and umount operations. Change-Id: I9b0318eb534f781f127882983527e1a221820478 Signed-off-by: Nir Soffer <nsoffer(a)redhat.com&gt; Reviewed-on: https://gerrit.ovirt.org/56544 Reviewed-by: Dan Kenigsberg <danken(a)redhat.com&gt; Continuous-Integration: Jenkins CI Reviewed-by: Francesco Romani <fromani(a)redhat.com&gt; Based on this, I posted https://gerrit.ovirt.org/c/95719/ Please try to rebase your patches on top of this, and report if it fixes this issue. Nir