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For leaf cgroups this tree is empty, so the > timer fires and exits without dispatching the throttled bio. > > The throttled bio sits in the parent's pending_tree with disptime set > to jiffies (THROTL_TG_CANCELING zeroes all dispatch times), but the > parent's timer is never explicitly rescheduled. The bio only gets > dispatched when the parent timer eventually fires at its previously > scheduled expiry. > > Fix by calling throtl_schedule_next_dispatch(sq->parent_sq, true) > instead, matching what tg_set_limit() already does. This forces the > parent's dispatch cycle to run immediately and flush all canceling > bios without waiting for a stale timer. > > Signed-off-by: Tao Cui Hello Tao, Trial runs of blktests CI for this patch caught the failure of test case throtl/004 using scsi_debug device. I tried to recreate the failure manually. I applied the patch on v7.1-rc4 kernel, and ran the test case and got the result below. Is this failure expected? # ./check throtl/004 throtl/004 (nullb) (delete disk while IO is throttled) [passed] runtime 1.546s ... 1.332s throtl/004 (sdebug) (delete disk while IO is throttled) [failed] runtime 2.654s ... 2.435s --- tests/throtl/004.out 2026-03-20 14:25:50.478000000 +0900 +++ /home/shin/Blktests/blktests/results/nodev_sdebug/throtl/004.out.bad 2026-05-20 21:26:14.470000000 +0900 @@ -1,3 +1,2 @@ Running throtl/004 -Input/output error Test complete