[PATCH v5 0/6] Fix races between blkcg code and request queue initialization and cleanup

Bart Van Assche
2018-02-28T18:15:27Z

Hello Jens,

Recently Joseph Qi identified races between the block cgroup code and request
queue initialization and cleanup. This patch series address these races.

This patch series is structured as follows:
- Patches 3..6 fix the aforementioned races.
- Patches 1..3 ensure that all maintained block drivers delete the gendisk
before cleaning up the request queue because patches 3..6 are only safe
if block driver shutdown uses this order. The gdrom driver (Sega Dreamcast
GD-ROM driver) has not been modified because from what I saw in the changelog
of this driver it seems to me like that driver is no longer in use. According
to what I found on the web production of Sega Dreamcast was stopped in 2001
(https://www.theguardian.com/business/2001/feb/01/4).

Please consider these patches for kernel v4.17.

Thanks,

Bart.

Changes between v4 and v5:
- Made the title of patch 4/6 more clear.
- Made the description of this patch series more detailed.

Changes between v3 and v4:
- Added three patches that fix the calling order of del_gendisk() and
blk_cleanup_queue() in multiple block drivers.

Changes between v2 and v3:
- Added a third patch that fixes a race between the blkcg code and queue
cleanup.

Changes between v1 and v2:
- Split a single patch into two patches.
- Dropped blk_alloc_queue_node2() and modified all block drivers that call
blk_alloc_queue_node().

Bart Van Assche (6):
block/loop: Delete gendisk before cleaning up the request queue
md: Delete gendisk before cleaning up the request queue
zram: Delete gendisk before cleaning up the request queue
block: Add a third argument to blk_alloc_queue_node()
block: Fix a race between the cgroup code and request queue
initialization
block: Fix a race between request queue removal and the block cgroup
controller

Bart Van Assche (6):
block/loop: Delete gendisk before cleaning up the request queue
md: Delete gendisk before cleaning up the request queue
zram: Delete gendisk before cleaning up the request queue
block: Add 'lock' as third argument to blk_alloc_queue_node()
block: Fix a race between the cgroup code and request queue
initialization
block: Fix a race between request queue removal and the block cgroup
controller

block/blk-core.c | 60 +++++++++++++++++++++++++++++++++++-------
block/blk-mq.c | 2 +-
block/blk-sysfs.c | 7 -----
drivers/block/drbd/drbd_main.c | 3 +--
drivers/block/loop.c | 2 +-
drivers/block/null_blk.c | 3 ++-
drivers/block/umem.c | 7 +++--
drivers/block/zram/zram_drv.c | 2 +-
drivers/ide/ide-probe.c | 2 +-
drivers/lightnvm/core.c | 2 +-
drivers/md/dm.c | 2 +-
drivers/md/md.c | 6 ++---
drivers/nvdimm/pmem.c | 2 +-
drivers/nvme/host/multipath.c | 2 +-
drivers/scsi/scsi_lib.c | 2 +-
include/linux/blkdev.h | 3 ++-
16 files changed, 70 insertions(+), 37 deletions(-)

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2.16.2