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27e6fa996c
linux/block
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Dennis Zhou (Facebook) 27e6fa996c blkcg: fix ref count issue with bio_blkcg using task_css 
The accessor function bio_blkcg either returns the blkcg associated with
the bio or finds one in the current context. This can cause an issue
when trying to associate a bio with a blkcg. Particularly, it's the
third case that is problematic:

	return css_to_blkcg(task_css(current, io_cgrp_id));

As the above may race against task migration and the cgroup exiting, it
is not always ok to take a reference on the blkcg returned from
bio_blkcg.

This patch adds association ahead of calling bio_blkcg rather than
after. This makes association a required and explicit step along the
code paths for calling bio_blkcg. blk_get_rl is modified as well to get
a reference to the blkcg it may use and blk_put_rl will always put the
reference back. Association is also moved above the bio_blkcg call to
ensure it will not return NULL in blk-iolatency.

BFQ and CFQ utilize this flaw, but due to the complexity, I do not want
to address this in this series. I've created a private version of the
function with notes not to use it describing the flaw. Hopefully soon,
that code can be cleaned up.

Signed-off-by: Dennis Zhou <dennisszhou@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21 20:29:02 -06:00
..
partitions partitions/aix: append null character to print data from disk 2018-07-27 09:17:41 -06:00
badblocks.c badblocks: fix wrong return value in badblocks_set if badblocks are disabled 2017-11-03 11:29:50 -07:00
bfq-cgroup.c blkcg: fix ref count issue with bio_blkcg using task_css 2018-09-21 20:29:02 -06:00
bfq-iosched.c blkcg: fix ref count issue with bio_blkcg using task_css 2018-09-21 20:29:02 -06:00
bfq-iosched.h block, bfq: inject other-queue I/O into seeky idle queues on NCQ flash 2018-09-14 13:06:03 -06:00
bfq-wf2q.c block, bfq: correctly charge and reset entity service in all cases 2018-09-14 13:06:02 -06:00
bio-integrity.c block: remove bio_rewind_iter() 2018-09-06 15:12:24 -06:00
bio.c blkcg: fix ref count issue with bio_blkcg using task_css 2018-09-21 20:29:02 -06:00
blk-cgroup.c blkcg: delay blkg destruction until after writeback has finished 2018-08-31 14:48:56 -06:00
blk-core.c block: don't warn when doing fsync on read-only devices 2018-09-05 16:14:36 -06:00
blk-exec.c blk-mq-sched: remove unused 'can_block' arg from blk_mq_sched_insert_request 2018-01-17 09:49:21 -07:00
blk-flush.c block: fix use-after-free in block flush handling 2018-06-09 06:37:14 -06:00
blk-integrity.c block drivers/block: Use octal not symbolic permissions 2018-05-24 13:38:59 -06:00
blk-ioc.c block, mm: remove unnecessary __GFP_HIGH flag 2018-07-09 09:07:54 -06:00
blk-iolatency.c blkcg: fix ref count issue with bio_blkcg using task_css 2018-09-21 20:29:02 -06:00
blk-lib.c block: fix infinite loop if the device loses discard capability 2018-07-09 09:07:54 -06:00
blk-map.c Merge branch 'for-4.16/block' of git://git.kernel.dk/linux-block 2018-01-29 11:51:49 -08:00
blk-merge.c block: don't use blocking queue entered for recursive bio submits 2018-06-02 20:35:00 -06:00
blk-mq-cpumap.c blk-mq: don't keep offline CPUs mapped to hctx 0 2018-04-10 08:38:46 -06:00
blk-mq-debugfs-zoned.c block: Make struct request_queue smaller for CONFIG_BLK_DEV_ZONED=n 2018-07-09 09:07:52 -06:00
blk-mq-debugfs.c blk-mq: dequeue request one by one from sw queue if hctx is busy 2018-07-09 09:07:53 -06:00
blk-mq-debugfs.h block: Make struct request_queue smaller for CONFIG_BLK_DEV_ZONED=n 2018-07-09 09:07:52 -06:00
blk-mq-pci.c blk-mq: code clean-up by adding an API to clear set->mq_map 2018-07-09 09:07:53 -06:00
blk-mq-rdma.c block: Add rdma affinity based queue mapping helper 2017-08-08 14:58:03 -04:00
blk-mq-sched.c blk-mq: init hctx sched after update ctx and hctx mapping 2018-08-21 09:02:55 -06:00
blk-mq-sched.h blk-mq: init hctx sched after update ctx and hctx mapping 2018-08-21 09:02:55 -06:00
blk-mq-sysfs.c block drivers/block: Use octal not symbolic permissions 2018-05-24 13:38:59 -06:00
blk-mq-tag.c for-4.19/post-20180822 2018-08-22 13:38:05 -07:00
blk-mq-tag.h Merge branch 'for-4.15/block' of git://git.kernel.dk/linux-block 2017-11-14 15:32:19 -08:00
blk-mq-virtio.c blk-mq: provide a default queue mapping for virtio device 2017-02-27 20:54:05 +02:00
blk-mq.c for-4.19/post-20180822 2018-08-22 13:38:05 -07:00
blk-mq.h blk-mq: issue directly if hw queue isn't busy in case of 'none' 2018-07-17 16:04:00 -06:00
blk-rq-qos.c blk-rq-qos: make depth comparisons unsigned 2018-07-22 11:30:53 -06:00
blk-rq-qos.h blk-rq-qos: make depth comparisons unsigned 2018-07-22 11:30:53 -06:00
blk-settings.c block: allow max_discard_segments to be stacked 2018-07-24 14:46:39 -06:00
blk-softirq.c block: fix timeout changes for legacy request drivers 2018-06-19 11:27:18 -06:00
blk-stat.c blk-stat: export helpers for modifying blk_rq_stat 2018-07-09 09:07:54 -06:00
blk-stat.h blk-stat: export helpers for modifying blk_rq_stat 2018-07-09 09:07:54 -06:00
blk-sysfs.c blk-wbt: don't maintain inflight counts if disabled 2018-08-23 09:34:46 -06:00
blk-tag.c for-linus-20180616 2018-06-17 05:37:55 +09:00
blk-throttle.c Blk-throttle: update to use rbtree with leftmost node cached 2018-09-20 19:31:46 -06:00
blk-timeout.c blk-mq: Fix timeout handling in case the timeout handler returns BLK_EH_DONE 2018-06-23 10:25:45 -06:00
blk-wbt.c blk-wbt: remove dead code 2018-08-27 13:32:12 -06:00
blk-wbt.h block: remove external dependency on wbt_flags 2018-07-09 09:07:54 -06:00
blk-zoned.c block: Remove a superfluous cast from blkdev_report_zones() 2018-07-09 09:07:52 -06:00
blk.h blk-mq: init hctx sched after update ctx and hctx mapping 2018-08-21 09:02:55 -06:00
bounce.c block: unexport bio_clone_bioset 2018-07-24 14:43:26 -06:00
bsg-lib.c block/bsg-lib: use PTR_ERR_OR_ZERO to simplify the flow path 2018-08-01 09:13:03 -06:00
bsg.c block: bsg: move atomic_t ref_count variable to refcount API 2018-08-27 19:17:02 -06:00
cfq-iosched.c blkcg: fix ref count issue with bio_blkcg using task_css 2018-09-21 20:29:02 -06:00
cmdline-parser.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
compat_ioctl.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
deadline-iosched.c block drivers/block: Use octal not symbolic permissions 2018-05-24 13:38:59 -06:00
elevator.c block: remove unnecessary condition check 2018-08-27 19:16:06 -06:00
genhd.c block: Track DISCARD statistics and output them in stat and diskstat 2018-07-18 08:44:22 -06:00
ioctl.c block: pass inclusive 'lend' parameter to truncate_inode_pages_range 2018-02-23 15:20:19 -07:00
ioprio.c block: add ioprio_check_cap function 2018-05-31 10:50:54 -04:00
Kconfig block: introduce blk-iolatency io controller 2018-07-09 09:07:54 -06:00
Kconfig.iosched License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kyber-iosched.c block: kyber: make kyber more friendly with merging 2018-05-30 10:47:40 -06:00
Makefile block: introduce blk-iolatency io controller 2018-07-09 09:07:54 -06:00
mq-deadline.c block drivers/block: Use octal not symbolic permissions 2018-05-24 13:38:59 -06:00
noop-iosched.c block: move existing elevator ops to union 2017-01-17 10:03:33 -07:00
opal_proto.h block: sed-opal: Set MBRDone on S3 resume path if TPER is MBREnabled 2017-09-11 09:45:52 -06:00
partition-generic.c block: Track DISCARD statistics and output them in stat and diskstat 2018-07-18 08:44:22 -06:00
scsi_ioctl.c block: consistently use GFP_NOIO instead of __GFP_NORECLAIM 2018-05-14 08:55:18 -06:00
sed-opal.c block: sed-opal: Fix a couple off by one bugs 2018-06-20 12:04:06 -06:00
t10-pi.c block: move dif_prepare/dif_complete functions to block layer 2018-07-30 08:27:02 -06:00