VMWare VM with RHEL and loop-device filesystem mounted locks up on attempt to make a snapshot

Issue

A VMWare-virtualized virtual machine running Red Hat Enterprise Linux 6 and having a filesystem on a loop device mounted locks up after taking a VMware snapshot. There are a lot of processes waiting for filesystems to be unfrozen (see __sb_start_write() call in the trace):

crash> bt 6934
PID: 6934   TASK: ffff8800b6f50aa0  CPU: 1   COMMAND: "sadc"
 #0 [ffff880062bedbc8] schedule at ffffffff815299f0
 #1 [ffff880062bedca0] __sb_start_write at ffffffff811900ec
 #2 [ffff880062bedd30] generic_file_aio_write at ffffffff81126969
 #3 [ffff880062bedd80] ext4_file_write at ffffffffa00a7e08 [ext4]
 #4 [ffff880062beddc0] do_sync_write at ffffffff8118dd6a
 #5 [ffff880062bedef0] vfs_write at ffffffff8118e068
 #6 [ffff880062bedf30] sys_write at ffffffff8118ea31
 #7 [ffff880062bedf80] system_call_fastpath at ffffffff8100b072

Escpecially, the call trace of vmtoolsd process is the following:

crash> bt 1205
PID: 1205   TASK: ffff8802362c2aa0  CPU: 0   COMMAND: "vmtoolsd"
 #0 [ffff8802379458a8] schedule at ffffffff815299f0
 #1 [ffff880237945980] io_schedule at ffffffff8152a233
 #2 [ffff8802379459a0] sync_buffer at ffffffff811c4f70
 #3 [ffff8802379459b0] __wait_on_bit at ffffffff8152acff
 #4 [ffff880237945a00] out_of_line_wait_on_bit at ffffffff8152ada8
 #5 [ffff880237945a70] __wait_on_buffer at ffffffff811c4f26
 #6 [ffff880237945a80] __sync_dirty_buffer at ffffffff811c5b91
 #7 [ffff880237945aa0] sync_dirty_buffer at ffffffff811c5c23
 #8 [ffff880237945ab0] journal_update_superblock at ffffffffa0176300 [jbd]
 #9 [ffff880237945b20] cleanup_journal_tail at ffffffffa01725fe [jbd]
#10 [ffff880237945b80] log_do_checkpoint at ffffffffa0172911 [jbd]
#11 [ffff880237945df0] journal_flush at ffffffffa0176620 [jbd]
#12 [ffff880237945e30] ext3_freeze at ffffffffa01a2dde [ext3]
#13 [ffff880237945e60] freeze_bdev at ffffffff811cc077
#14 [ffff880237945ea0] do_vfs_ioctl at ffffffff811a3a9b
#15 [ffff880237945f30] sys_ioctl at ffffffff811a3ea1
#16 [ffff880237945f80] system_call_fastpath at ffffffff8100b072