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Groups > linux.debian.user > #270042

Having ten thousands of mount bind causes various processes to go into loops

From Julien Petit <julien@nethik.fr>
Newsgroups linux.debian.user
Subject Having ten thousands of mount bind causes various processes to go into loops
Date 2024-06-12 12:20 +0200
Message-ID <IOtfb-2mws-7@gated-at.bofh.it> (permalink)
Organization linux.* mail to news gateway

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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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Thread

Having ten thousands of mount bind causes various processes to go  into loops Julien Petit <julien@nethik.fr> - 2024-06-12 12:20 +0200
  Re: Having ten thousands of mount bind causes various processes to go  into loops Max Nikulin <manikulin@gmail.com> - 2024-06-12 18:20 +0200
  Re: Having ten thousands of mount bind causes various processes to go  into loops Richard <rrosner5@gmail.com> - 2024-06-12 19:10 +0200
    Re: Having ten thousands of mount bind causes various processes to go  into loops Julien Petit <julien@nethik.fr> - 2024-06-14 12:00 +0200
      Re: Having ten thousands of mount bind causes various processes to go  into loops Richard <rrosner5@gmail.com> - 2024-06-14 13:00 +0200
        Re: Having ten thousands of mount bind causes various processes to go  into loops Julien Petit <julien@nethik.fr> - 2024-06-19 11:10 +0200

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