If a ublk server process releases a ublk char device file, any requests dispatched to the ublk server but not yet completed will retain a ref value of UBLK_REFCOUNT_INIT. Before commit e63d2228ef83 ("ublk: simplify aborting ublk request"), __ublk_fail_req() would decrement the reference count before completing the failed request. However, that commit optimized __ublk_fail_req() to call __ublk_complete_rq() directly without decrementing the request reference count. The leaked reference count incorrectly allows user copy and zero copy operations on the completed ublk request. It also triggers the WARN_ON_ONCE(refcount_read(&io->ref)) warnings in ublk_queue_reinit() and ublk_deinit_queue(). Commit c5c5eb24ed61 ("ublk: avoid ublk_io_release() called after ublk char dev is closed") already fixed the issue for ublk devices using UBLK_F_SUPPORT_ZERO_COPY or UBLK_F_AUTO_BUF_REG. However, the reference count leak also affects UBLK_F_USER_COPY, the other reference-counted data copy mode. Fix the condition in ublk_check_and_reset_active_ref() to include all reference-counted data copy modes. This ensures that any ublk requests still owned by the ublk server when it exits have their reference counts reset to 0. Signed-off-by: Caleb Sander Mateos Fixes: e63d2228ef83 ("ublk: simplify aborting ublk request") --- drivers/block/ublk_drv.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index df9831783a13..78f3e22151b9 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -1581,12 +1581,11 @@ static void ublk_set_canceling(struct ublk_device *ub, bool canceling) static bool ublk_check_and_reset_active_ref(struct ublk_device *ub) { int i, j; - if (!(ub->dev_info.flags & (UBLK_F_SUPPORT_ZERO_COPY | - UBLK_F_AUTO_BUF_REG))) + if (!ublk_dev_need_req_ref(ub)) return false; for (i = 0; i < ub->dev_info.nr_hw_queues; i++) { struct ublk_queue *ubq = ublk_get_queue(ub, i); -- 2.45.2