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  1. 17 3月, 2018 2 次提交
    • J
      blk-throttle: fix race between blkcg_bio_issue_check() and cgroup_rmdir() · 4c699480
      由 Joseph Qi 提交于 
      We've triggered a WARNING in blk_throtl_bio() when throttling writeback
io, which complains blkg->refcnt is already 0 when calling blkg_get(),
and then kernel crashes with invalid page request.
After investigating this issue, we've found it is caused by a race
between blkcg_bio_issue_check() and cgroup_rmdir(), which is described
below:

writeback kworker               cgroup_rmdir
                                  cgroup_destroy_locked
                                    kill_css
                                      css_killed_ref_fn
                                        css_killed_work_fn
                                          offline_css
                                            blkcg_css_offline
  blkcg_bio_issue_check
    rcu_read_lock
    blkg_lookup
                                              spin_trylock(q->queue_lock)
                                              blkg_destroy
                                              spin_unlock(q->queue_lock)
    blk_throtl_bio
    spin_lock_irq(q->queue_lock)
    ...
    spin_unlock_irq(q->queue_lock)
  rcu_read_unlock

Since rcu can only prevent blkg from releasing when it is being used,
the blkg->refcnt can be decreased to 0 during blkg_destroy() and schedule
blkg release.
Then trying to blkg_get() in blk_throtl_bio() will complains the WARNING.
And then the corresponding blkg_put() will schedule blkg release again,
which result in double free.
This race is introduced by commit ae118896 ("blkcg: consolidate blkg
creation in blkcg_bio_issue_check()"). Before this commit, it will
lookup first and then try to lookup/create again with queue_lock. Since
revive this logic is a bit drastic, so fix it by only offlining pd during
blkcg_css_offline(), and move the rest destruction (especially
blkg_put()) into blkcg_css_free(), which should be the right way as
discussed.

Fixes: ae118896 ("blkcg: consolidate blkg creation in blkcg_bio_issue_check()")
Reported-by: NJiufei Xue <jiufei.xue@linux.alibaba.com>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      4c699480
    • J
      block: sed-opal: fix u64 short atom length · 5f990d31
      由 Jonas Rabenstein 提交于 
      The length must be given as bytes and not as 4 bit tuples.
Reviewed-by: NScott Bauer <scott.bauer@intel.com>
Signed-off-by: NJonas Rabenstein <jonas.rabenstein@studium.uni-erlangen.de>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      5f990d31
  3. 14 3月, 2018 3 次提交
  5. 13 3月, 2018 2 次提交
  7. 10 3月, 2018 1 次提交
  9. 09 3月, 2018 15 次提交
  11. 07 3月, 2018 2 次提交
  13. 01 3月, 2018 15 次提交