Red Hat Bugzilla – Bug 166375
dmesg > /var/log/dmesg hangs and breaks boot up on AMD64 notebook
Last modified: 2007-11-30 17:11:12 EST
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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):
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 :-)
1.1502_FC5 and 1.1504_FC5 work fine.