This is definitely not a PAM plugin bug. It is likely not a documentation issue.
The key is EACCESS reading /proc/self/exe. Failed setuid/setgid can be a reason.
1. Please attach full strace of mysqld. Comment #5 states that there are setuid failures however they don't present in attached logs.
2. Make sure that mysqld operates with user/group which have access to mysqld binary
This is definitely not a PAM plugin bug. It is likely not a documentation issue.
The key is EACCESS reading /proc/self/exe. Failed setuid/setgid can be a reason.
1. Please attach full strace of mysqld. Comment #5 states that there are setuid failures however they don't present in attached logs.
2. Make sure that mysqld operates with user/group which have access to mysqld binary