1. 23 Sep, 2020 5 commits
  2. 15 Sep, 2020 5 commits
  3. 14 Sep, 2020 1 commit
    • Tejun Heo's avatar
      iocost: fix infinite loop bug in adjust_inuse_and_calc_cost() · aa67db24
      Tejun Heo authored
      adjust_inuse_and_calc_cost() is responsible for reducing the amount of
      donated weights dynamically in period as the budget runs low. Because we
      don't want to do full donation calculation in period, we keep latching up
      inuse by INUSE_ADJ_STEP_PCT of the active weight of the cgroup until the
      resulting hweight_inuse is satisfactory.
      
      Unfortunately, the adj_step calculation was reading the active weight before
      acquiring ioc->lock. Because the current thread could have lost race to
      activate the iocg to another thread before entering this function, it may
      read the active weight as zero before acquiring ioc->lock. When this
      happens, the adj_step is calculated as zero and the incremental adjustment
      loop becomes an infinite one.
      
      Fix it by fetching the active weight after acquiring ioc->lock.
      
      Fixes: b0853ab4 ("blk-iocost: revamp in-period donation snapbacks")
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      aa67db24
  4. 11 Sep, 2020 6 commits
  5. 10 Sep, 2020 20 commits
  6. 08 Sep, 2020 3 commits