iCloud (unless 'Keep Downloaded') folder shared in virtiofs results in EDEADLK (Resource deadlock avoided)

[cameronkerrnz]

Description

I didn't see this behaviour documented anywhere, and thought it must be a bug until I realised it affected some content but not others... so worthwhile documenting because I had a very frustrating time with this, being new to Lima.

macOS Sequoia 15.6.1 on Apple M1

❯ limactl --version
limactl version 1.2.1
❯ limactl start --name default --mount-writable 
❯ lima                                          

ckerr@lima-default:/Users/ckerr/Desktop/cobra-tutorial$ cat myapp/go.mod 
cat: myapp/go.mod: Resource deadlock avoided

ckerr@lima-default:/Users/ckerr/Desktop/cobra-tutorial$ strace -f cat myapp/main.go 

openat(AT_FDCWD, "myapp/main.go", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=676, ...}) = 0
fadvise64(3, 0, 0, POSIX_FADV_SEQUENTIAL) = 0
mmap(NULL, 270336, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xe7f562b32000
read(3, 0xe7f562b33000, 262144)         = -1 EDEADLK (Resource deadlock avoided)

ckerr@lima-default:/Users/ckerr/Desktop/cobra-tutorial$ mount | grep /Users
mount0 on /Users/ckerr type virtiofs (ro,relatime)

This issue is not resolved until I right-click on the folder and specify 'Keep Downloaded'

Likely this will be more of an issue for people using VM software such as Lima, which will put more pressure on available disk space; I found that even on the folder I was currently working with, many of the files had already been sucked up into iCloud and not locally available... my local instance of Go or VSCode didn't seem to care, but Go (or just cat) inside the VM certainly did.

[jandubois]

When you access the files from macOS directly, they will be "downloaded on demand", so the fact that they have migrated should be transparent.

But this mechanism doesn't seem to work for access over virtiofs, which may work at a layer below the one intercepted by the iCloud syncing.

So documentation is probably all we can do.

If you are out of space, then you have to do what you have to do, but putting development folders directly into cloud-based directories is generally not a good idea, especially if this contains a git repo, as the cloud sync may corrupt the internal structure under the .git directory.