fs.copyFileSync hangs for file created within same layer in overlay filesystem

[ericsciple]

Since upgrading node 12, we are seeing fs.copyFileSync hang during some container scenarios.

We should revert the node 12 update and continue the investigation. It's worth noting node 16 has the same issue.

Related issues:

• setup-buildx-action hangs with 99% CPU when running on latest Github Action Runner v2.285.0 docker/setup-buildx-action#117
• fs.copyFileSync hangs for file created within same layer in overlay filesystem nodejs/node#40200

[crazy-max]

Thanks @ericsciple!

[ericsciple]

Two immediate action items:

• Revert to older version of node 12
• Create simplest possible repro we can provide for nodejs

[ericsciple]

fyi - the new runner finished rolling out to all accounts. We reverted back to the previous version of node12.

[ericsciple]

OK here's the simplest repro that @ethomson and I could come up with:

• Follow these three instructions to get a shell to a container running in kubernetes
• Copy paste commands from this script

Key details about the repro:

• Reproduces on AKS and EKS (not minikube and not docker)
• Uses copy_file_range to perform the copy
• Copy a file from non-overlay file system to overlay file system, then from overlay file system to another location on the overlay file system (always copies 0 bytes)

[ericsciple]

Opened an AKS issue here

[ethomson]

The most recent EKS AMIs (I'm using 1.21.5-20220123) are running kernel 5.4.172-90.336.amzn2 which has reverted this overlayfs behavior change.

In other words, fs.fileCopySync() now works properly on EKS.

[thboop]

@ericsciple and I went through this and it appears to be fixed in AKS as well, and it is not reproducible on ubuntu-latest, so we should be good to re-update node12 and close this issue