On Sat, 20 Nov 2004 05:18:05 +0000, Dan LaBell wrote:

> Anyway, I wrote a quick and dirty file copy program that used mmap for 
> io.   Mounted a 31 meg mfs on /tmp (swapping only to a 32meg file ) ,  
> overflowed /tmp a few times,  experienced only the expected outcome:  
> diskfull messages.   Afterwards I umounted /tmp, and did a shutdown -p 
> now,  after typical shutdown banter I got:
>   shutdown: can't exec /sbin/halt:  Exec format error.
> File on /sbin/halt says its a 'core file' of mmdup, my test program.
> Ok. now this is weird: I cp  file,  in order to run gdb on the core 
> file, and gdb reports its not a core file, file on the copy says its an 
> executable.   I try gdb using /sbin/halt directly and it
> nominally works,  but I can' examing anything.   Looking at the file 
> with a hex editor it looks like its only been partially overwritten 
> with the core file.   I think it has to be a result of overflowing the 
> mfs.   (as  I did no error checking, so running out of space would 
> result in a core dump, and the current directory was /tmp, which was 
> mfs. )
> I going to be reboot, fsck and see if halt fixes itself.     How can 
> the copy be ok,
> and the original be corrupt?  Is it a memory map gone awry?
> 
> I don't know -- I'm just taking a wild guess, that it could be related, 
> unless of course it isn't, and its something else ;-].

It sound like the problem described in PR kern/27802: on disk full,
last-edited file opened instead of binary.

Could you please append your observations to that PR?

Bye	Pavel