Red Hat Bugzilla – Bug 166974
System hangs: problems with shared memory?
Last modified: 2007-11-30 17:07:08 EST
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Description of problem:
In testing of a High Availability database we have see kernel related problems with shared memory.
The database is a heavy user of SVr4 shared memory.
In the process of taking down the database and freeing shared memory we has seen complete hangs of the system. On 4-ways (2 Xeon w/HT) systems we see two processes each eating up one CPU.
$ ipcs -s
then just hangs, however
$ ipcs -m
works. The two processes eating CPU can't be killed and we has to reboot to recover the machine.
On two-way systems we see more complete hangs as is't not possible to login, however we get answer from ping. We has to reboot to get the machine in shape.
We wonder if this is a timing/race problem in the shared memory kernel code as it's not possible to reproduce the problem at will, but happens from time to time.
These machines are running RHEL AS 3 U4 with kernel-smp-2.4.21-27.EL, the hardware is Xeon 2.8 GHz and 1 GB RAM.
BTW: We have not seen these problems on Solaris 9 and 10 and Windows 2003 Enterprise Edition.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
Obviously we'll need more information to go on.
Preferably, can you set the machine up with netdump and/or diskdump,
and then forcibly crash the machine with alt-sysrq-c when the hang
Short of that, when it's in that state, can you capture the output
This bug is filed against RHEL 3, which is in maintenance phase.
During the maintenance phase, only security errata and select mission
critical bug fixes will be released for enterprise products. Since
this bug does not meet that criteria, it is now being closed.
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If you feel this bug is indeed mission critical, please contact your
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information on how this bug is affecting you.