Patch Name:  PHKL_9909

Patch Description: s700 10.20 system hang due to LVM and VxFS deadlock

Creation Date: 97/01/22

Post Date:  97/02/04

Hardware Platforms - OS Releases:
        s700: 10.20

Products: N/A

Filesets:
        OS-Core.CORE-KRN

Automatic Reboot?: Yes

Status: General Superseded

Critical:
        Yes
        PHKL_9909: HANG

Path Name:  /hp-ux_patches/s700/10.X/PHKL_9909

Symptoms:
        PHKL_9909:
        A deadlock can occur on system 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_9909:
        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. The routine 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, umount or sync on a JFS logical volume.

        The fix for this problem is to pass the vfsp to
        walk_and_freeze_fs() from ufs_freeze() instead of the
        do_sync argument. The routine walk_and_freeze_fs()
        now uses vfsp when it calls update().

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: 97/01/22 10:23:07 $ $Revision:
                        1.20.98.10 $ PATCH_10.20 (PHKL_9909)

cksum(1) Output:
        1282487902 20372 /usr/conf/lib/libufs.a(ufs_vfsops.o)

Patch Conflicts: None

Patch Dependencies:  None

Hardware Dependencies:  None

Other Dependencies:  None

Supersedes:  None

Equivalent Patches:
        PHKL_9910:
        s800: 10.20

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_9909

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

                swinstall -x autoreboot=true -x match_target=true \
                        -s /tmp/PHKL_9909.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_9909.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_9909.  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_9909.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_9909.depot of=/dev/rmt/0m bs=2k

Special Installation Instructions:  None