Re: 12.3: "swapon -a" crashes the system

09.12.2021 13:11, Peter wrote:

>  if you run out of swapspace and you think you might just create
> some extra devices and add them to /etc/fstab and then run "swapon -a"
> to enable them, don't do that.
> 
> The result might look like this:
> kernel: pid 12296 (daemon), jid 5, uid 5100: exited on signal 10 (core dumped)
> kernel: pid 17717 (ruby27), jid 5, uid 5100: exited on signal 6 (core dumped)
> kernel: pid 14938 (daemon), jid 10, uid 5100: exited on signal 10 (core dumped)
> kernel: pid 19184 (ruby27), jid 10, uid 5100: exited on signal 11 (core dumped)
> kernel: pid 19182 (ruby27), jid 10, uid 5100: exited on signal 10 (core dumped)
> ...
> with a subsequent kernel crash.
> 
> In my case I did run out of swapspace despite proper sizing, because
> of unbalanced numa-domains. (Each of them may hit free_target on their
> own behalf, and then start paging.)
> 
> So I did as described above, but I added them with the "late" option,
> and then did run "swapon -a", which did not even add them - but
> nevertheless produced the crash. The processes that do coredump might
> be those that are fully swapped out?

Did you try using ZFS-backed files or devices for swap? If so, this is somewhat expected.