Having ten thousands of mount bind causes various processes to go into
From
Julien Petit@21:1/5 to
All on Wed Jun 12 12:20:01 2024
Dear,
Not sure i should report a bug so here is a report first. For more
than 10 years now, we've been using mount binds to create shares rw or
ro. It's been working perfectly under older Debian. A few months ago,
we migrated to Ubuntu Jammy and started having processes running 100%
non stop. While examining the processes in question, we could see the
same thing: it seemed to be reading all the mounts indefinitely.
It started with the phpsessionclean.service. We managed to fix it
editing /lib/systemd/system/phpsessionclean.service and disabling
sandboxing entries. But then it started to happen with other
processes.
Anything related to systemd seems affected in a way. For instance, we
cannot start haproxy if the mounts are mounted.
We tested with the last Debian and it is affected too.
We understand that 14 000 mounts is a lot. So maybe our usage will be questioned. But this has been working for ages so why not now?
The problem can be very easily reproduced:
1. Launch the latest Debian stable
2. Execute the following script to create mounts:
#!/bin/bash
mkdir /home/test/directories
mkdir /home/test/mounts
for i in {1..14000}
do
echo "Mounting dir $i"
mkdir "/home/test/directories/dir_$i"
mkdir "/home/test/mounts/dir_$i"
mount --bind -o rw "/home/test/directories/dir_$i" "/home/test/mounts/dir_$i"
done
After that, the "top" command will show processes getting stuck using
100% of CPU never ending.
Has anyone a clue if this is fixable? Should i report a bug?
Thanks for your help.
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