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DescriptionThorsten Schlichting
2012-08-23 15:52:19 UTC
The kernel-debug package does not contain debug code for ext3 journal replay.
grep CONFIG_JBD_DEBUG /boot/config-2.6.32-279.5.1.el6.x86_64.debug
# CONFIG_JBD_DEBUG is not set
If this is a mistake, please include it in one of the future updates if it doesn't make too much difficulties.
It's great to have a kernel quick by hand with debug options enabled, compiling took me several hours.
From fs/jbd/Kconfig:
config JBD_DEBUG
bool "JBD (ext3) debugging support"
depends on JBD && DEBUG_FS
help
If you are using the ext3 journaled file system (or potentially any
other file system/device using JBD), this option allows you to
enable debugging output while the system is running, in order to
help track down any problems you are having. By default the
debugging output will be turned off.
If you select Y here, then you will be able to turn on debugging
with "echo N > /sys/kernel/debug/jbd/jbd-debug", where N is a
number between 1 and 5, the higher the number, the more debugging
output is generated. To turn debugging off again, do
"echo 0 > /sys/kernel/debug/jbd/jbd-debug".
BTW: CONFIG_JBD2_DEBUG (for ext4) is also not set....
This is not a mistake, adding kernel DEBUG config options is not something we do for production kernels.
Thanks!
Comment 3Thorsten Schlichting
2012-08-24 11:59:29 UTC
Sorry, you misunderstood. I did not ask for the production kernel package, I asked for the kernel-debug package. For example
kernel-debug-2.6.32-279.5.1.el6.x86_64.rpm
From the package description:
...
This variant of the kernel has numerous debugging options enabled.
It should only be installed when trying to gather additional information
on kernel bugs, as some of these options impact performance noticably.
Thorsten, we don't turn on every debug option even in kernel-debug.
Can you describe how this option was useful to you?
ISTR this generates quite a bit of system log traffic, that may be one reason we left it off.
I'm guessing this is related to bug # 850803 / case # 00676179 ?
Comment 6Thorsten Schlichting
2012-08-27 08:50:22 UTC
Hi Eric,
they didn't tell me the BZ number and I do not have access to 850803, but yes, it's related to case # 00676179.
AFAIR there were no extra log messages until enabled by /sys/kernel/debug/jbd/jbd-debug. Shall I check this?
Sorry, you are right - jbd_debug doesn't do anything by default unless /sys/kernel/debug/jbd/jbd-debug is set to some threshold.
We'll have to consider this one a bit more I think. Since CONFIG_JBD[2]_DEBUG isn't run too often, I want to be sure there is no possibility of regressions if it gets enabled. I'll go ahead & put it back into ASSIGNED for now.
Comment 10RHEL Program Management
2013-06-19 22:19:34 UTC
This request was evaluated by Red Hat Product Management for
inclusion in a Red Hat Enterprise Linux release. Product
Management has requested further review of this request by
Red Hat Engineering, for potential inclusion in a Red Hat
Enterprise Linux release for currently deployed products.
This request is not yet committed for inclusion in a release.
Confirmed CONFIG_JBD_DEBUG and CONFIG_JBD2_DEBUG are "y" on kernel-2.6.32-422.el6, and regression tests on debug kernel show no issues
# egrep "JBD.?_DEBUG" /boot/config-2.6.32-422.el6.x86_64.debug
CONFIG_JBD_DEBUG=y
CONFIG_JBD2_DEBUG=y
Set to VERIFIED.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
http://rhn.redhat.com/errata/RHSA-2013-1645.html
The kernel-debug package does not contain debug code for ext3 journal replay. grep CONFIG_JBD_DEBUG /boot/config-2.6.32-279.5.1.el6.x86_64.debug # CONFIG_JBD_DEBUG is not set If this is a mistake, please include it in one of the future updates if it doesn't make too much difficulties. It's great to have a kernel quick by hand with debug options enabled, compiling took me several hours. From fs/jbd/Kconfig: config JBD_DEBUG bool "JBD (ext3) debugging support" depends on JBD && DEBUG_FS help If you are using the ext3 journaled file system (or potentially any other file system/device using JBD), this option allows you to enable debugging output while the system is running, in order to help track down any problems you are having. By default the debugging output will be turned off. If you select Y here, then you will be able to turn on debugging with "echo N > /sys/kernel/debug/jbd/jbd-debug", where N is a number between 1 and 5, the higher the number, the more debugging output is generated. To turn debugging off again, do "echo 0 > /sys/kernel/debug/jbd/jbd-debug". BTW: CONFIG_JBD2_DEBUG (for ext4) is also not set....