Comment 8 for bug 1766543

By the way the task blocks on the following :

==> /proc/54255/task/54255/stack <==
[<c000000000103a1c>] wakeup_preempt_entity.isra.6+0x7c/0x90
[<c000000000015df8>] __switch_to+0x1f8/0x350
[<c00000000054cd9c>] get_request+0x29c/0x910
[<c000000000550d64>] blk_queue_bio+0x164/0x500
[<c00000000054e274>] generic_make_request+0x154/0x310
[<c00000000054e504>] submit_bio+0xd4/0x1f0
[<c0000000003b805c>] ext4_io_submit+0x7c/0xb0
[<c0000000003b2938>] ext4_writepages+0x4a8/0xdd0
[<c000000000243090>] do_writepages+0x60/0xc0
[<c000000000230988>] __filemap_fdatawrite_range+0xf8/0x170
[<c000000000416378>] jbd2_journal_begin_ordered_truncate+0xe8/0x130
[<c0000000003b5c70>] ext4_evict_inode+0x530/0x5e0
[<c00000000030d488>] evict+0xf8/0x2a0
[<c0000000002fe668>] do_unlinkat+0x1a8/0x3a0
[<c000000000009284>] system_call+0x38/0xe4