Hi,
During my weeks of extensive stress testing of aufs I noticed this bug
happened twice on one of the servers:
May 31 20:05:42 kirtest dockerd[3912]:
time="2019-05-31T20:05:42.686603244Z" level=warning msg="auplink flush
failed: auplink:plink.c:158: proc: No such file or directory\n"
error="exit status 2" method=Unmount storage-driver=aufs
Jun 07 08:25:29 kirtest dockerd[28894]:
time="2019-06-07T08:25:29.886758371Z" level=warning msg="auplink flush
failed: auplink:plink.c:158: proc: No such file or directory\n"
error="exit status 2" method=Unmount storage-driver=aufs
(the warnings are from docker that runs "auplink flush" before
unmounting)
As you can see, it happens very very rare, only two times for 10 days
of testing.
I took a look at the source code, and it seems that auplink binary
fails to openA /proc/fs/aufs/plink_maint file for writing. I do not
understand why this could ever happen.
This happened on Ubuntu 18.04 with the following kernel and aufs
module:
# uname -a
Linux kirtest 4.15.0-50-generic #54-Ubuntu SMP Mon May 6 18:46:08 UTC
2019 x86_64 x86_64 x86_64 GNU/Linux
# modinfo aufs | head -3
filename: A A A
/lib/modules/4.15.0-50-generic/kernel/fs/aufs/aufs.ko
alias: A A A A A fs-aufs
version: A A A A 4.15-20180219
There are no relevant messages in the kernel log either, or any other
system logs, meaning nothing was going on during the times of the
incident but massively parallel mounting/unmounting of different aufs
mounts.
Not sure how useful all this is, but figured I'd report it anyway.
Regards,
A Kir.
