udev fails to pick up changes made on block devices

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 6
  • udev between 147-2.46.el6_4.2 and 147-2.63

Issue

  • With the most recent version of udev on RHEL 6.4 udev no longer picks up change events from my block devices.
  • I have an empty sdb on which I create a filesystem, after which I expect udev to create the appropritate links under /dev/disk.
    • With udev up to 147-2.46.el6_4.2 I get the links automatically, after upgrading to 147-2.46.el6_4.4 I don't get the links without rebooting or manually poking udev.

Resolution

This issue has been addressed and resolved in RHBA-2015:1382

Root Cause

  • An earlier update was made to increase the amount of udev workers when some workers were stuck during network module loading, but an incorrect semaphore counter was used. As a consequence, the amount of workers was not increased, and if all workers were busy, timeouts could occur and some events were not correctly processed. With this update, the correct semaphore counter is used, and the amount of available workers now increases as expected.

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