ZGC: Failed to truncate backing file (Permission denied) at startup after 14.0.2 to 15.0.1 upgrade

[Per Liden]

Hi David,

On 11/24/20 10:51 AM, David Tavoularis wrote:
> Hi Per,
> 
> Thanks to your help, we identified that 15.0.1 (with ZGC) was starting 
> fine with recent container-selinux versions (2.33/2.36/2.42), but was 
> broken with older one (2.21) :
> - Not working : container-selinux-2.21-2.gitba103ac.el7.noarch
> - Working     : container-selinux-2.33-1.git86f33cd.el7.noarch
> - Working     : container-selinux-2.36-1.gitff95335.el7.noarch
> - Working     : container-selinux-2.42-1.gitad8f0f7.el7.noarch
> 

Good to hear!

> We will plan to upgrade the nodes running with old version.
> 
> Just for my information, is there a plan to support the old buggy 
> container-selinux in openjdk-15.0.2 by implementing a fallback to 
> fallocate when ftruncate returns EACCESS ?

A fallback using lseek+write would probably work. If it's worth 
implement and maintain such a thing depends on how common this problem 
is in the real world. You are the fist one report this issue, so I sort 
of assume it's not that common. Recommending people to use a more 
up-to-date version of the container-selinux package seems like a 
reasonable workaround/fix at this time. Of course, if this turns out to 
be a common issue we can reconsider.

cheers,
Per