ublk_batch_prep_io() calls __ublk_fetch() while holding io->lock spinlock. When the last IO makes the device ready, ublk_mark_io_ready() tries to acquire ub->cancel_mutex which can sleep, causing a sleeping-while-atomic bug. Fix by moving ublk_mark_io_ready() out of __ublk_fetch() and into the callers (ublk_fetch and ublk_batch_prep_io) after the spinlock is released. Reported-by: Jens Axboe Fixes: b256795b3606 ("ublk: handle UBLK_U_IO_PREP_IO_CMDS") Signed-off-by: Ming Lei --- drivers/block/ublk_drv.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 1e374ecbf0f1..31279a8238b8 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -3064,7 +3064,6 @@ static int __ublk_fetch(struct io_uring_cmd *cmd, struct ublk_device *ub, WRITE_ONCE(io->task, NULL); else WRITE_ONCE(io->task, get_task_struct(current)); - ublk_mark_io_ready(ub, q_id); return 0; } @@ -3083,6 +3082,8 @@ static int ublk_fetch(struct io_uring_cmd *cmd, struct ublk_device *ub, ret = __ublk_fetch(cmd, ub, io, q_id); if (!ret) ret = ublk_config_io_buf(ub, io, cmd, buf_addr, NULL); + if (!ret) + ublk_mark_io_ready(ub, q_id); mutex_unlock(&ub->mutex); return ret; } @@ -3484,6 +3485,9 @@ static int ublk_batch_prep_io(struct ublk_queue *ubq, io->buf = buf; ublk_io_unlock(io); + if (!ret) + ublk_mark_io_ready(data->ub, ubq->q_id); + return ret; } -- 2.47.0