Red Hat Bugzilla – Bug 124689
Machine hang triggered by mkisofs
Last modified: 2007-11-30 17:10:43 EST
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.6) Gecko/20040115
Description of problem:
Running mkisofs, with option '-h' results in a machine hang.
Input and can be either from NFS or local disk. Input has
to be at least abt. 50 MB large. Typically, when 95 to 99%
is done (as says the -v option), the program stalls, and
consumes 100% CPU. No extra memory seems to be consumed.
A few seconds later, the machine grinds to a halt completely.
No swapping noise, no disk io.
It does not happen always, but definitely more than 90% of the
time. Without option '-h', all works perfectly.
An strace reported a 'munmap' as the last syscall.
Version-Release number of selected component (if applicable):
kernel-smp-2.6.5-1.358 and mkisofs-2.01-0.a27.3
Steps to Reproduce:
1. Choose a directory tree with abt. 50 MB or more.
2. mkisofs -v -h -o rubbish.iso <this_directory_tree>
3. Wait for 95% finished.
The machine uses 100% CPU (Which I could see running it on an SMP).
This lasts for a short time (seconds). Then there's a complete freeze.
Mkisofs should have exited normally. Or if need be crash. But should
never trigger a machine hang.
Update: with kernel-2.6.6-1.406, I can no longer trigger it; but
in SMP with kernel-smp-2.6.6-1.406 it is still present.
Update: kernel-2.6.6-1.422 seems not to have it. kernel-smp-2.6.6-1.422
in SMP still has it, though slightly differently: the mkisofs-process
goes into 100% system, is un-interrruptible; console of machine is
dead, but remote access to the machine is okay. Hard reboot is still
We're at 2.6.6-1.427smp now, with mkisofs-2.01-0.a27.4. Still getting
a 100% CPU un-interruptible proces. Not getting any wiser from the
/proc info for that process neither.
A collegue of mine figured out that the 4G/4G patch is the culprit:
without it, no problems.
we fixed a rare cornercase in the 4g/4g patch in 435 kernel (out as
erratum now) that may explain this....
Yap, problem fixed in 2.6.6-1.435smp, thanks!