Patch Name:  PHKL_7904

Patch Description: s700 10.01 System Hang due to LVM/VxFS deadlock

Creation Date: 96/08/29

Post Date:  96/09/02

Hardware Platforms - OS Releases:
        s700: 10.01

Products: N/A

Filesets:
        OS-Core.CORE-KRN

Automatic Reboot?: Yes

Status: General Superseded

Critical:
        Yes
        PHKL_7904: HANG

Path Name:  /hp-ux_patches/s700/10.X/PHKL_7904

Symptoms:
        PHKL_7904:
        A deadlock can occur on systems running LVM, JFS and HFS.
        The hang was introduced by one process running lvmerge
        on HFS logical volumes and another process running umount
        on a JFS logical volume. This deadlock can only occur with
        the following scenario:

        1) Process A is running a lvmerge or a lvsplit on a HFS
            logical volume
        2) Process B is running a mount, umount or sync on a JFS
            logical volume

Defect Description:
        PHKL_7904:
        A deadlock resulted from a process running lvmerge on HFS
        logical volumes, and another process running umount on a
        JFS logical volume. The umount process grabs the JFS update
        sleep lock (used to serialize JFS syncs/mounts/umounts),
        calls spec_close to close the device we are unmounting, and
        eventually gets to a LVM close routine which is sleeping
        waiting to acquire the LVM volume-group lock. The lvmerge
        process is holding the LVM volume-group lock and proceeds
        to call freeze_and_sync_fs_dev() to freeze and sync the
        file system associated with the device. ufs_freeze() is
        first called which in turn calls walk_and_freeze_fs()
        without a pointer to a vfs structure. This proves faulty
        since update() is now called without a vfsp and will
        proceed to try and sync every mounted file system instead
        of just the file system being frozen; so we proceeded to
        try and sync a JFS file system which first tries to grab
        the JFS update sleep lock, and a deadlock occurs. This
        problem can be reproduced by having one process running a
        lvsplit or lvmerge on a HFS logical volume, and another
        process running a mount, unmount or sync on a JFS logical
        volume.

SR:
        5003328237

Patch Files:
        /usr/conf/lib/libufs.a(ufs_vfsops.o)

what(1) Output:
        /usr/conf/lib/libufs.a(ufs_vfsops.o):
                ufs_vfsops.c $Date: 96/08/29 06:44:53 $ $Revision: 1
                        .14.72.43 $ PATCH_10.01 (PHKL_7904)

cksum(1) Output:
        3450192315 20216 /usr/conf/lib/libufs.a(ufs_vfsops.o)

Patch Conflicts: None

Patch Dependencies:  None

Hardware Dependencies:  None

Other Dependencies:  None

Supersedes:  None

Equivalent Patches: None

Patch Package Size:  70 Kbytes

Installation Instructions:
        Please review all instructions and the Hewlett-Packard
        SupportLine User Guide or your Hewlett-Packard support terms
        and conditions for precautions, scope of license,
        restrictions, and, limitation of liability and warranties,
        before installing this patch.
        ------------------------------------------------------------
        1. Back up your system before installing a patch.

        2. Login as root.

        3. Copy the patch to the /tmp directory.

        4. Move to the /tmp directory and unshar the patch:

                cd /tmp
                sh PHKL_7904

        5a. For a standalone system, run swinstall to install the
            patch:

                swinstall -x autoreboot=true -x match_target=true \
                        -s /tmp/PHKL_7904.depot

        5b. For a homogeneous NFS Diskless cluster run swcluster on the
            server to install the patch on the server and the clients:

                swcluster -i -b

            This will invoke swcluster in the interactive mode and
            force all clients to be shut down.

            WARNING: All cluster clients must be shut down prior to the
                     patch installation.  Installing the patch while the
                     clients are booted is unsupported and can lead to
                     serious problems.

            The swcluster command will invoke an swinstall session in which
            you must specify:

                alternate root path  -  default is /export/shared_root/OS_700
                source depot path    -  /tmp/PHKL_7904.depot

            To complete the installation, select the patch by choosing
            "Actions -> Match What Target Has" and then "Actions -> Install"
            from the Menubar.

        5c. For a heterogeneous NFS Diskless cluster:

                - run swinstall on the server as in step 5a to install
                  the patch on the cluster server.

                - run swcluster on the server as in step 5b to install
                  the patch on the cluster clients.

        By default swinstall will archive the original software in
        /var/adm/sw/patch/PHKL_7904.  If you do not wish to retain a
        copy of the original software, you can create an empty file
        named /var/adm/sw/patch/PATCH_NOSAVE.

        Warning: If this file exists when a patch is installed, the
                 patch cannot be deinstalled.  Please be careful
                 when using this feature.

        It is recommended that you move the PHKL_7904.text file to
        /var/adm/sw/patch for future reference.

        To put this patch on a magnetic tape and install from the
        tape drive, use the command:

                dd if=/tmp/PHKL_7904.depot of=/dev/rmt/0m bs=2k

Special Installation Instructions:  None