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Bug 166375 - dmesg > /var/log/dmesg hangs and breaks boot up on AMD64 notebook
dmesg > /var/log/dmesg hangs and breaks boot up on AMD64 notebook
Product: Fedora
Classification: Fedora
Component: kernel (Show other bugs)
x86_64 Linux
medium Severity high
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Assigned To: Kernel Maintainer List
Brian Brock
Depends On:
  Show dependency treegraph
Reported: 2005-08-19 16:59 EDT by Alexandre Oliva
Modified: 2007-11-30 17:11 EST (History)
1 user (show)

See Also:
Fixed In Version: kernel-2.6.12-1.1502_FC5
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2005-08-21 16:08:46 EDT
Type: ---
Regression: ---
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Documentation: ---
Verified Versions:
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oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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Description Alexandre Oliva 2005-08-19 16:59:31 EDT
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.8b3) Gecko/20050818 Fedora/1.1-0.2.7.deerpark.alpha2.1 Firefox/1.0+

Description of problem:
Boot up would hang on my notebook as soon as I first tried kernel-2.6.12-1.1499_FC5, right after enabling swap partitions.  Further investigation has revealed that it was the rc.sysinit command `dmesg -s 131072 > /var/log/dmesg' that stopped the boot from making progress.

I forced an fsck of all filesystems on kernel-2.6.12-1.1492_FC5, that boots up just fine, to no avail.

I booted up 1499_FC5 with init=/bin/bash, remounted / rw and ran dmesg > /tmp/dmesg (same filesystem), and that worked.  dmesg > /var/log/dmesg, however, would still hang.  true > /var/log/dmesg wouldn't, and would successfully zero out the file.  Moving the existing /var/log/dmesg out of the way was no use either; dmesg > /var/log/dmesg would still hang.

strace /bin/dmesg completed successfully; strace /bin/dmesg > /tmp/dmesg did as well; writes were line-buffered in the first case, and in 4KiB blocks in the second, as expected.  strace /bin/dmesg > /var/log/dmesg would succeed in the first two 4KiB writes to stdout, but the third would never complete.

After the first failure, the system came back up with /dev/md8 in need of resync.  /dev/md8 is the raid 1 device holding the physical volume that contains (part of?) the logical volume containing the root filesystem.  In all other cases /dev/md8 was resyncing, and this didn't seem to affect the results.

I tried to make sure the problem was not related with sbp2 or usb-storage (I've got two external disks on which swap and raid devices are mounted), and either they're both broken, or the problem is unrelated with them.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1.Boot up an AMD64 notebook onto 1.1499_FC5
2.After it hangs, reboot with init=/bin/bash
3.Remount / rw, then run dmesg > /var/log/dmesg

Actual Results:  It hangs

Expected Results:  1.1492_FC5 doesn't, and that was good :-)

Additional info:
Comment 1 Alexandre Oliva 2005-08-21 16:08:46 EDT
1.1502_FC5 and 1.1504_FC5 work fine.

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