Xenial SRU - UbuntuKVM guest crashed while running I/O stress test with Ubuntu kernel 4.4.0-47-generic

[Tim Gardner]

https://bugs.launchpad.net/bugs/1659111

See attached.

Though this looks like a big scary patch set, the 2 big prerequisite
backports are largely mechanical changes with no functional changes.
Subsequent patches are clean cherry-picks and righteous bug fixes (or
minor backports). I've run some stress-ng and ecryptfs stress tests
without any errors. I/O stress testing from IBM is also positive.

rtg
-- 
Tim Gardner tim.gardner at canonical.com
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The following changes since commit 35a205408a75512b0d58b66cbd3c45d8f1eff136:

  UBUNTU: Ubuntu-4.4.0-73.94 (2017-04-06 14:05:34 +0100)

are available in the git repository at:

  git://kernel.ubuntu.com/rtg/ubuntu-xenial.git ppc64el-lp1659111

for you to fetch changes up to e627b189cd829e92aad51990f7a114223a28b15d:

  block: Fix oops scsi_disk_get() (2017-04-07 12:05:13 +0100)

----------------------------------------------------------------
Jan Kara (23):
      block: Unhash block device inodes on gendisk destruction
      block: Use pointer to backing_dev_info from request_queue
      block: Dynamically allocate and refcount backing_dev_info
      block: Make blk_get_backing_dev_info() safe without open bdev
      block: Get rid of blk_get_backing_dev_info()
      block: Move bdev_unhash_inode() after invalidate_partition()
      block: Unhash also block device inode for the whole device
      block: Revalidate i_bdev reference in bd_aquire()
      block: Initialize bd_bdi on inode initialization
      block: Move bdi_unregister() to del_gendisk()
      block: Allow bdi re-registration
      bdi: Fix use-after-free in wb_congested_put()
      block: Make del_gendisk() safer for disks without queues
      block: Fix bdi assignment to bdev inode when racing with disk delete
      bdi: Mark congested->bdi as internal
      bdi: Make wb->bdi a proper reference
      bdi: Unify bdi->wb_list handling for root wb_writeback
      bdi: Shutdown writeback on all cgwbs in cgwb_bdi_destroy()
      bdi: Do not wait for cgwbs release in bdi_unregister()
      bdi: Rename cgwb_bdi_destroy() to cgwb_bdi_unregister()
      block: Fix oops in locked_inode_to_wb_and_lock_list()
      kobject: Export kobject_get_unless_zero()
      block: Fix oops scsi_disk_get()

 block/blk-cgroup.c               |   6 +-
 block/blk-core.c                 |  47 +--
 block/blk-integrity.c            |   4 +-
 block/blk-sysfs.c                |   6 +-
 block/blk-wbt.c                  | 751 +++++++++++++++++++++++++++++++++++++++
 block/compat_ioctl.c             |   7 +-
 block/genhd.c                    |  17 +-
 block/ioctl.c                    |   7 +-
 drivers/block/aoe/aoeblk.c       |   4 +-
 drivers/block/drbd/drbd_main.c   |   6 +-
 drivers/block/drbd/drbd_nl.c     |  10 +-
 drivers/block/drbd/drbd_proc.c   |   2 +-
 drivers/block/drbd/drbd_req.c    |   2 +-
 drivers/block/pktcdvd.c          |   4 +-
 drivers/block/rbd.c              |   2 +-
 drivers/md/bcache/request.c      |  10 +-
 drivers/md/bcache/super.c        |   8 +-
 drivers/md/dm-cache-target.c     |   2 +-
 drivers/md/dm-era-target.c       |   2 +-
 drivers/md/dm-table.c            |   2 +-
 drivers/md/dm-thin.c             |   2 +-
 drivers/md/dm.c                  |   6 +-
 drivers/md/linear.c              |   2 +-
 drivers/md/md.c                  |   6 +-
 drivers/md/multipath.c           |   2 +-
 drivers/md/raid0.c               |   6 +-
 drivers/md/raid1.c               |   4 +-
 drivers/md/raid10.c              |  10 +-
 drivers/md/raid5.c               |  12 +-
 fs/block_dev.c                   |  43 ++-
 fs/btrfs/disk-io.c               |   2 +-
 fs/btrfs/volumes.c               |   2 +-
 fs/gfs2/ops_fstype.c             |   2 +-
 fs/nilfs2/super.c                |   2 +-
 fs/super.c                       |   2 +-
 fs/xfs/xfs_buf.c                 |   3 +-
 fs/xfs/xfs_buf.h                 |   1 -
 include/linux/backing-dev-defs.h |   8 +-
 include/linux/backing-dev.h      |  12 +-
 include/linux/blkdev.h           |   3 +-
 include/linux/fs.h               |   2 +
 include/linux/kobject.h          |   2 +
 include/linux/writeback.h        |   1 +
 lib/kobject.c                    |   5 +-
 mm/backing-dev.c                 | 162 ++++++---
 mm/page-writeback.c              |   4 +-
 46 files changed, 1034 insertions(+), 171 deletions(-)
 create mode 100644 block/blk-wbt.c