System hangs when pre-quiescing a snapshot in VMware Environment

Issue

• Analyzing vmcore, many processes are in D-state, such as:

1685      1   0  ffff880136973500  UN   0.0  185460   4312  vmtoolsd

• The root filesystem and boot filesystem are in FROZEN state:

crash> mount
    VFSMOUNT         SUPERBLK     TYPE   DEVNAME                      DIRNAME
ffff88013d64fd80 ffff88013d64b000 rootfs rootfs                       /         
ffff88013d64f380 ffff88013d659400 proc   /proc                        /proc     
ffff88013ccd8ac0 ffff88013d64b400 sysfs  /sys                         /sys      
ffff88013d64f280 ffff88013ccda800 devtmpfs udev                         /dev      
ffff88013d64f180 ffff88013889e400 devpts devpts                       /dev/pts  
ffff88013ccd89c0 ffff880138ba3400 tmpfs  tmpfs                        /dev/shm  
ffff88013d64f080 ffff8801384fbc00 ext4   /dev/mapper/VolGroup-lv_root /         
ffff880136a89e80 ffff8801384fe800 usbfs  /proc/bus/usb                /proc/bus/usb
ffff880136a89d80 ffff88013874b000 ext4   /dev/sda1                    /boot     
ffff88013ccd88c0 ffff880138712000 binfmt_misc none                         /proc/sys/fs/binfmt_misc
ffff880136a89c80 ffff880137ec8000 rpc_pipefs sunrpc                       /var/lib/nfs/rpc_pipefs
crash> super_block.s_frozen ffff8801384fbc00
  s_frozen = 2
crash> super_block.s_frozen ffff88013874b000
  s_frozen = 2

• It is in VMware Environment when trying to take quiesced snapshot.
• System hangs.
• VMSync driver