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Using Eric's program from the original bug (see comment 6) I was able to narrow
it down to just one file /dev/watchdog triggering the crash (and also a link in
/dev/char/10:130).
Steps to reproduce:
1. Compile Eric's program from the original bug (comment #6) or use filecap
tool from libcap-ng-utils package.
2. Run it on /dev/watchdog:
# ./bz591831 /dev/watchdog
# filecap /dev/watchdog
3. Wait 20-30 seconds for the crash to occur
Additional info:
Always reprducible on my system.
$ uname -a
Linux ****** 2.6.32-28.el6.x86_64 #1 SMP Thu May 20 14:03:38 EDT 2010 x86_64
x86_64 x86_64 GNU/Linux
This is expected behavior! /dev/watchdog is backed by a hardware timer (if your system has it) which starts when the file is opened and panics if there is no write to the watchdog file in a short period of time. The idea is that you an write a program in userspace that write to /dev/watchdog every second or two and the system will panic if userspace becomes unresponsive.
We might be able to report this against libcap-ng-utils and ask that its operation be changed from
open()
fgetxattr()
close()
to just use getxattr() without the open/close.
There is certainly no kernel bug here. If you open /dev/watchdog and don't do anything else the system is supposed to panic.
Built libcap-ng-0.6.4-3.el6 to resolve this problem.
Comment 9releng-rhel@redhat.com
2010-11-10 21:02:06 UTC
Red Hat Enterprise Linux 6.0 is now available and should resolve
the problem described in this bug report. This report is therefore being closed
with a resolution of CURRENTRELEASE. You may reopen this bug report if the
solution does not work for you.