Weird chmod behaviour

[Matthew Dillon]

:Hey,
:
:I had just finished updating to a very recent kernel (yesterday, HEAD), 
:and ran make upgrade. After this I couldn't use top(1) any more. It 
:reported access problems with /dev/mem (or /dev/kmem? dunno, doesn't 
:matter really).
:
:so this came up (after a fresh make upgrade!)

:[...]
:+ mknod kmem c 2 1 root:kmem
:+ rm -f kmem
:+ /sbin/mknod kmem c 2 1 root:kmem
:+ chmod 640 kmem
:[...]
:21:37:49 corecode at sweatshorts:/dev % ll kmem
:crw-------  1 root  kmem    2,   1 Nov 17 21:37 kmem
:
:something was changing the mode, but I didn't run any weird program, so 
:I suspect the kernel. Unfortunately I'm no longer able to reproduce it, 
:still I could do so several times in a row.
:
:cheers
:   simon

    I couldn't reproduce it either.  

    The next time this happens try to do the rm, mknod, and chmod manually
    and see if that works.  

    Then run ktrace -i on the command you were using that reproduced the 
    problem and if the problem is still present ship the ktrace file over
    to leaf.  e.g.

    ktrace -f /tmp/kt.out -i make upgrade

					-Matt
					Matthew Dillon 
					<dillon at xxxxxxxxxxxxx>