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rr-debugger / rr

Record and Replay Framework
http://rr-project.org/
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overlayfs results in pack warnings #3346

Open maleadt opened 2 years ago

maleadt commented 2 years ago

I'm generating and packing an rr trace from within a sandboxed environment that uses overlayfs for the root:

$ mount overlay on / type overlay (rw,relatime,lowerdir=/tmp/jl_JkU4oM,upperdir=/tmp/jl_nBQTiT/upper/rootfs,workdir=/tmp/jl_nBQTiT/work/rootfs,index=off,metacopy=off)

This works fine, but results in a deluge of warnings during rr pack:

[ERROR src/TraceStream.cc:1166:read_mapped_region() errno: ENOSYS] Metadata of /usr/lib/x86_64-linux-gnu/ld-2.28.so changed: replay divergence likely, but continuing anyway. inode: 687473/635070; mode: 33133/33133; uid: 1000/1000; gid: 1000/1000; size: 165632/165632; mtime: 1658868582/1658868582

It's obviously the same file being processed here, so there won't be a divergence IIUC. @Keno mentioned that this is due to overlayfs lying about inode numbers, maybe he can elaborate some more.

khuey commented 2 years ago

We could demote this to WARN instead of ERROR (perhaps only if everything but the inode number matches).