[Core Dump] Signal 7 (SIGBUS) (code: nonexistent physical address) on making archive of currently running OS (possibly bad use case) about dwarfs

[mhx]

Oh, that is unfortunate. It must have taken a while to get there.

The primary source of bus errors in DwarFS are memory mapped files that disappear or change shape while being mapped. A long term goal is to place the memory-mapping code behind an abstraction layer and have an alternative implementation using regular file I/O. The latter would likely be slower, but would be safe from SIGBUS.

When running mkdwarfs, all input files are memory mapped sooner or later, sometimes multiple times. If these files change shape while being accessed, this can lead to SIGBUS.

In the past, it has been more likely that DwarFS images residing on faulty USB media were the cause of bus errors and failed to extract or caused the FUSE driver to crash.

I don't think this is due to RAM shortage. As you've already pointed out, the most likely cause is files being mutated while also being accessed by mkdwarfs.

I'm inclined to close this as wontfix — but please let me know if you can reproduce this when the input to mkdwarfs is not being mutated.

[samuelwatsonofficial]

I'm happy to close this off as I stated earlier copying all the files first before making an archive is reasonable if it is being changed, thanks for the quick response.