OSP17.1 | Collectd hugepages plugin complains about not being able to open file OSP17.1 on RHEL9 collectd.log file shows: ------------------------ [2023-02-06 13:54:19] plugin_load: plugin "hugepages" successfully loaded. [2023-02-06 13:54:54] hugepages: cannot open /sys/kernel/mm/hugepages/hugepages-1048576kB/demote [2023-02-06 13:54:54] hugepages: cannot open /sys/devices/system/node/node0/hugepages/hugepages-1048576kB/demote [2023-02-06 13:54:59] hugepages: cannot open /sys/kernel/mm/hugepages/hugepages-1048576kB/demote [2023-02-06 13:54:59] hugepages: cannot open /sys/devices/system/node/node0/hugepages/hugepages-1048576kB/demote [2023-02-06 13:55:04] hugepages: cannot open /sys/kernel/mm/hugepages/hugepages-1048576kB/demote [2023-02-06 13:55:04] hugepages: cannot open /sys/devices/system/node/node0/hugepages/hugepages-1048576kB/demote [2023-02-06 13:55:09] hugepages: cannot open /sys/kernel/mm/hugepages/hugepages-1048576kB/demote [2023-02-06 13:55:09] hugepages: cannot open /sys/devices/system/node/node0/hugepages/hugepages-1048576kB/demote [2023-02-06 13:55:14] hugepages: cannot open /sys/kernel/mm/hugepages/hugepages-1048576kB/demote ------------------------ Same issue was reported here: https://github.com/collectd/collectd/issues/3993
OSP16.2 RHEL 8.4 /sys/kernel/mm/hugepages/ ------- [root@ctrl-0-16-2 hugepages-1048576kB]# ls -al total 0 drwxr-xr-x. 2 root root 0 Jan 25 04:23 . drwxr-xr-x. 4 root root 0 Jan 25 04:23 .. -r--r--r--. 1 root root 4096 Jan 25 04:23 free_hugepages -rw-r--r--. 1 root root 4096 Jan 30 17:43 nr_hugepages -rw-r--r--. 1 root root 4096 Jan 30 17:43 nr_hugepages_mempolicy -rw-r--r--. 1 root root 4096 Jan 31 21:24 nr_overcommit_hugepages -r--r--r--. 1 root root 4096 Jan 30 17:43 resv_hugepages -r--r--r--. 1 root root 4096 Jan 30 17:43 surplus_hugepages OSP17.1 RHEL 9.2. /sys/kernel/mm/hugepages/ ---------------- [root@controller-0 hugepages-1048576kB]# ls -al total 0 drwxr-xr-x. 2 root root 0 Feb 6 13:54 . drwxr-xr-x. 4 root root 0 Feb 6 12:51 .. --w-------. 1 root root 4096 Feb 6 13:54 demote -rw-r--r--. 1 root root 4096 Feb 6 13:54 demote_size -r--r--r--. 1 root root 4096 Feb 6 13:54 free_hugepages -rw-r--r--. 1 root root 4096 Feb 6 13:54 nr_hugepages -rw-r--r--. 1 root root 4096 Feb 6 13:54 nr_hugepages_mempolicy -rw-r--r--. 1 root root 4096 Feb 6 13:54 nr_overcommit_hugepages -r--r--r--. 1 root root 4096 Feb 6 13:54 resv_hugepages -r--r--r--. 1 root root 4096 Feb 6 13:54 surplus_hugepages
According to [1] the write-only permission on "demote" file is expected. ~~~ demote is used to demote a number of huge pages. A user with root privileges can write to this file. It may not be possible to demote the requested number of huge pages. To determine how many pages were actually demoted, compare the value of nr_hugepages before and after writing to the demote interface. demote is a write only interface. ~~~ [1] https://docs.kernel.org/admin-guide/mm/hugetlbpage.html
collectd-5.12.0-10.el9ost.x86_64 Fixed. No hugepages logs in collectd.log file anymore.
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 (Release of components for Red Hat OpenStack Platform 17.1 (Wallaby)), 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/RHEA-2023:4577