New Features and Changes

• You can now use User-Level Statically Defined Tracing (USDT) probes in 32-bit applications on 64-bit hosts.

• The d_path() D subroutine requires its argument to be a pointer to a path structure that corresponds to a file that is known to the current task.

Fixed Bugs

• A minor memory leak with the DTrace help tracing facility has been fixed. When the dtrace.ko module was loaded, a buffer (by default 64K) was allocated and never released.

• Stack backtraces are more accurate as a result of various fixes to adjust the number of frames to skip for specific probes.

• The stack depth was being determined by requesting a backtrace to be written into a temporary buffer that was being allocated (vmalloc), which posed significant problems when probes were executing in a context that does not support memory allocations. The buffer is now obtained from the scratch area of memory that DTrace provides for probe processing.

• A system crash could occur if you passed an invalid pointer to d_path(). Due to its implementation, it is not possible to depend on safe memory accesses to avoid this. Now you must validate the pointer before calling d_path().

New Features and Changes

• The dtrace-utils-devel package now requires the corresponding version of the dtrace-utils package.

• The dtrace-utils package has been renamed.

• There is a new dtrace -vV option which reports information on the released version of DTrace, as well as the internal ID of dtrace(1) and libdtrace(1).

• The <dtrace.h> header file can be included to support development of DTrace consumer applications.

• DTrace only loads D libraries from directories with a name that corresponds to the current running kernel.

Fixed Bugs

• Processes that receive SIGTRAP during normal operation now work even when being traced. Previously, the SIGTRAP was ignored.

• DTrace no longer loses track of processes that perform exec() while DTrace is examining their dynamic linker state.

• DTrace no longer leaves breakpoints in forked processes.

• DTrace no longer considers that it knows the state of the symbol table of processes it has stopped monitoring.

• DTrace no longer crashes multi-threaded processes that use dlopen() or dlclose().

• If you use the --alloc-start option with mkfs.btrfs to specify an offset for the start of the file system, the size of the file system should be smaller but this is not the case. It is also possible to specify an offset that is higher than the device size. (Bug ID 16946255)

• The usage information for mkfs.btrfs reports raid5 and raid6 as possible profiles for both data and metadata. However, the kernel does not support these features and cannot mount file systems that use them. (Bug ID 16946303)

• The btrfs filesystem balance command does not warn that the RAID level can be changed under certain circumstances, and does not provide the choice of cancelling the operation. (Bug ID 16472824)

• Converting an existing ext2, ext3, or ext4 root file system to btrfs does not carry over the associated security contexts that are stored as part of a file's extended attributes. With SELinux enabled and set to enforcing mode, you might experience many permission denied errors after reboot, and the system might be unbootable. To avoid this problem, enforce automatic file system relabeling to run at bootup time. To trigger automatic relabeling, create an empty file named .autorelabel (for example, by using touch) in the file system's root directory before rebooting the system after the initial conversion. The presence of this file instruct SELinux to recreate the security attributes for all files on the file system. If you forget to do this and rebooting fails, either temporarily disable SELinux completely by adding selinux=0 to the kernel boot parameters, or disable enforcing of the SELinux policy by adding enforcing=0. (Bug ID 13806043)

• Commands such as du can show inconsistent results for file sizes in a btrfs file system when the number of bytes that is under delayed allocation is changing. (Bug ID 13096268)

• The copy-on-write nature of btrfs means that every operation on the file system initially requires disk space. It is possible that you cannot execute any operation on a disk that has no space left; even removing a file might not be possible. The workaround is to run sync before retrying the operation. If this does not help, remount the file system with the -o nodatacow option and delete some files to free up space. See https://btrfs.wiki.kernel.org/index.php/ENOSPC.

• On Oracle Linux 6, btrfs has a limit of 237 or fewer hard links to a file from a single directory. The exact limit depends on the number of characters in the file name. The limit is 237 for a file with up to eight characters in its file name; the limit is lower for longer file names. Attempting to create more than this number of links results in the error Too many links. You can create more hard links to the same file from another directory. Although the limitation of the number of hard links in a single directory has been increased to 65535, the version of mkfs.btrfs that is provided in the btrfs-progs package does not yet support the compatibility flag for this feature. Oracle Linux 7 includes a later version of btrfs-progs package, which does support the increased number of hard links. (Bug ID 16285431)

• If you run the btrfs quota enable command on a non-empty file system, any existing files do not count toward space usage. Removing these files can cause usage reports to display negative numbers and the file system to be inaccessible. The workaround is to enable quotas immediately after creating the file system. If you have already written data to the file system, it is too late to enable quotas. (Bug ID 16569350)

• The btrfs quota rescan command is not currently implemented on Oracle Linux 6. The command does not perform a rescan and returns without displaying any message. (Bug ID 16569350)

• When you overwrite data in a file, starting somewhere in the middle of the file, the overwritten space is counted twice in the space usage numbers that btrfs qgroup show displays. (Bug ID 16609467)

• If you run btrfsck --init-csum-tree on a file system and then run a simple btrfsck on the same file system, the command displays a Backref mismatch error that was not previously present. (Bug ID 16972799)

• If you use the -s option to specify a sector size to mkfs.btrfs that is different from the page size, the created file system cannot be mounted. By default, the sector size is set to be the same as the page size. (Bug ID 17087232)

• Defragmentation can break data block sharing. Due to the copy-on-write design of btrfs, snapshots initially share the same data blocks of the original subvolume. However, when either the snapshot or the subvolume is defragmented, this sharing can be undone, resulting in a higher disk space usage.

• Argument declarations for probe definitions cannot be declared with derived types such as enum, struct, or union.

• The following compiler warning can be ignored for probe definition arguments of type string (which is a D type but not a C type):

  provider_def.h:line#: warning: parameter names (without types) in function declaration

• Multi-threaded processes under ustack(), usym(), uaddr() and umod() which perform dlopen() in threads other than the first thread may not have accurate symbol resolution for symbols introduced by the dlopen().

• The inline data feature that allows the data of small files to be stored inside their inodes is not yet available.
  The -O inline_data option to the mkfs.ext4 and tune2fs commands is not supported. (Bug ID 17210654)

• If fallocate is used to write to an ext4 file system that has the bigalloc feature enabled, this causes a kernel panic. (Bug ID 20712768)

• HVM guests

• PV guests

• Oracle Database

• After you take a snapshot of a virtual machine and then use the Save action to save the virtual machine state, you might not be able to revert to the virtual machine to the snapshot using the Revert action. The workaround is to click on the last snapshot listed in the Snapshot area for the virtual machine, and then select Apply. (Bug ID 20110077)

• Oracle Linux 7 virtual machines that use Legacy Network mode lose their network connectivity if more than one virtual CPU is configured. The workaround is to configure only one virtual CPU for Oracle Linux 7 virtual machines. (Bug ID 20110058)

• Oracle Linux 6 virtual machines running on Windows Server 2012R2 display truncated messages during a system shutdown or reboot. (Bug ID Bug 20090500)

• You might see the following warning messages if you use the ibportstate disable command to disable a switch port:

  ibwarn: [2696] _do_madrpc: recv failed: Connection timed out
  ibwarn: [2696] mad_rpc: _do_madrpc failed; dport (Lid 38)
  ibportstate: iberror: failed: smp set portinfo failed

  You can safely ignore these warnings. (Bug ID 16248314)

• The Internet Protocol over InfiniBand (IPoIB) driver supports the use of either connected mode or datagram mode with an interface, where datagram mode is the default mode. Changing the mode of an InfiniBand interface by echoing either connected or datagram to /sys/class/net/ibN/mode is not supported. It is also not possible to change the mode of an InfiniBand interface while it is enabled.

  To change the IPoIB mode of an InfiniBand interface:

  1. Edit the /etc/sysconfig/network-scripts/ifcfg-ibN configuration file, where N is the number of the interface:

     • To configure connected mode, specify CONNECTED_MODE=yes in the file.

     • To configure datagram mode, either specify CONNECTED_MODE=no in the file or do not specify this setting at all (datagram mode is enabled by default).

     Note

     Before saving your changes, make sure that you have not specified more than one setting for CONNECTED_MODE in the file.

  2. To enable the specified mode on the interface, use the following commands to take down the interface and bring it back up:

     # ifdown ibN
     # ifup ibN

  (Bug ID 17479833)

• Using yum to update packages inside the container that use init scripts can undo changes made by the Oracle template.

• Migrating live containers (lxc-checkpoint) is not yet supported.

• If a Device or resource busy - failed to set memory.use_hierarchy to 1 error message is displayed when you start a container, edit the /etc/cgconfig.conf file and add the following:

  group . {
  memory {
  memory.use_hierarchy = "1";
  }
  }

  (Bug ID 19237222)

• When booting UEK R3 as a PVHVM guest, you can safely ignore the following kernel message:

  register_vcpu_info failed:
            err=-38

  (Bug ID 13713774)

• Under Oracle VM Server 3.1.1, migrating a PVHVM guest that is running the UEK R3 kernel causes a disparity between the date and time as displayed by date and hwclock. To prevent this from occurring, upgrade to Oracle VM Server 3.2.1 or later. The workaround post migration is either to run the command hwclock --hctosys on the guest or to reboot the guest. (Bug ID 16861041)

• On virtualized systems that are built on Xen version 3, including all releases of Oracle VM 2 including 2.2.2 and 2.2.3, disk synchronization requests for ext3 and ext4 file systems result in journal corruption with kernel messages similar to the following being logged:

  blkfront: barrier: empty write xvda op failed
  blkfront: xvda: barrier or flush: disabled

  In addition, journal failures such as the following might be reported:

  Aborting journal on device xvda1

  The workaround is to add the mount option barrier=0 to all ext3 and ext4 file systems in the guest VM before upgrading to UEK R3. For example, you would change a mount entry such as:

  UUID=4e4287b1-87dc-47a8-b69a-075c7579eaf1  /  ext3  defaults  1 1

  so that it reads:

  UUID=4e4287b1-87dc-47a8-b69a-075c7579eaf1  /  ext3  defaults,barrier=0  1 1

  This issue does not apply to Xen 4 based systems, such as Oracle VM 3. (Bug ID 17310816)

• Xen does not support the crashkernel=auto parameter for Kdump configuration. (Bug ID 18174580)

• Mounting or changing an ISO image in a PVHVM guest results in exception messages in the Oracle VM console. The ISO image itself is mounted correctly and is accessible. (Bug ID 19972081)

• You cannot increase (hot plug) the number of virtual CPUs in a running Oracle Linux 7 guest using the xm vcpu-set command. Decreasing the number of virtual CPUs does work. (Bug ID 18865156)

• In order to use jumbo frames with any network interface card on an Oracle VM Server, you must increase the swiotlb kernel parameter to 256 by setting swiotlb=256 in the kernel boot line in /boot/grub/grub.conf. (Bug ID 20333068)

• In some circumstances on Oracle Linux 6 systems, xfsdump can fail when the file system to be backed up is specified as a mount point, for example:

  xfsdump: ERROR: /mnt/myxfs/ does not identify a file system

  The workaround is to specify the file system by its device name, for example /dev/sdb. (Bug ID 18483275)

• In a virtual machine, the intensive direct I/O on files which are being fragmented by fallocate and punch_hole in parallel may result, in some circumstances, in data corruption with the error Invalid or incomplete multibyte or wide character. (Bug ID 18711409)

• The following message might be displayed when you use the xfs_growfs command:

   xfs_growfs: cannot find mount point for path `mount_point': Success 

  The message is caused by an incorrect mounted project path listed in the XFS project quota initialization file, /etc/projects. If you are not using project quotas, remove the /etc/projects file. (Bug ID 18886520)

• On Oracle Linux 6, an XFS file system can become corrupted if all of its inodes are used. (Bug ID 19217280)

• On Oracle Linux 7, xfs_copy fails to copy a file system if the device sector size more than 512 bytes. (Bug ID 19267663)

• xsf_repair causes a segmentation fault when you try repair a file system using a short reporting interval (-t). (Bug ID 20015850)

• When you create an XFS file system using the -i maxpct option, it does not actually limit the space allocated to inodes. (Bug ID 20430515)

• Mounting an XFS file system that was created using the -n ftype=1 option results in a mount error and the file system cannot be mounted. The ftype option is not supported in UEK R3. (Bug ID 20511541)