From: Xiang Chen chenxiang66@hisilicon.com
[ Upstream commit 550c0d89d52d3bec5c299f69b4ed5d2ee6b8a9a6 ]
For IOs from upper layer, preemption may be disabled as it may be called by function __blk_mq_delay_run_hw_queue which will call get_cpu() (it disables preemption). So if flags HISI_SAS_REJECT_CMD_BIT is set in function hisi_sas_task_exec(), it may disable preempt twice after down() and up() which will cause following call trace:
BUG: scheduling while atomic: fio/60373/0x00000002 Call trace: dump_backtrace+0x0/0x150 show_stack+0x24/0x30 dump_stack+0xa0/0xc4 __schedule_bug+0x68/0x88 __schedule+0x4b8/0x548 schedule+0x40/0xd0 schedule_timeout+0x200/0x378 __down+0x78/0xc8 down+0x54/0x70 hisi_sas_task_exec.isra.10+0x598/0x8d8 [hisi_sas_main] hisi_sas_queue_command+0x28/0x38 [hisi_sas_main] sas_queuecommand+0x168/0x1b0 [libsas] scsi_queue_rq+0x2ac/0x980 blk_mq_dispatch_rq_list+0xb0/0x550 blk_mq_do_dispatch_sched+0x6c/0x110 blk_mq_sched_dispatch_requests+0x114/0x1d8 __blk_mq_run_hw_queue+0xb8/0x130 __blk_mq_delay_run_hw_queue+0x1c0/0x220 blk_mq_run_hw_queue+0xb0/0x128 blk_mq_sched_insert_requests+0xdc/0x208 blk_mq_flush_plug_list+0x1b4/0x3a0 blk_flush_plug_list+0xdc/0x110 blk_finish_plug+0x3c/0x50 blkdev_direct_IO+0x404/0x550 generic_file_read_iter+0x9c/0x848 blkdev_read_iter+0x50/0x78 aio_read+0xc8/0x170 io_submit_one+0x1fc/0x8d8 __arm64_sys_io_submit+0xdc/0x280 el0_svc_common.constprop.0+0xe0/0x1e0 el0_svc_handler+0x34/0x90 el0_svc+0x10/0x14 ...
To solve the issue, check preemptible() to avoid disabling preempt multiple when flag HISI_SAS_REJECT_CMD_BIT is set.
Link: https://lore.kernel.org/r/1571926105-74636-5-git-send-email-john.garry@huawe... Signed-off-by: Xiang Chen chenxiang66@hisilicon.com Signed-off-by: John Garry john.garry@huawei.com Signed-off-by: Martin K. Petersen martin.petersen@oracle.com Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/scsi/hisi_sas/hisi_sas_main.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c index 7211578..ff5330b 100644 --- a/drivers/scsi/hisi_sas/hisi_sas_main.c +++ b/drivers/scsi/hisi_sas/hisi_sas_main.c @@ -612,7 +612,13 @@ static int hisi_sas_task_exec(struct sas_task *task, gfp_t gfp_flags, dev = hisi_hba->dev;
if (unlikely(test_bit(HISI_SAS_REJECT_CMD_BIT, &hisi_hba->flags))) { - if (in_softirq()) + /* + * For IOs from upper layer, it may already disable preempt + * in the IO path, if disable preempt again in down(), + * function schedule() will report schedule_bug(), so check + * preemptible() before goto down(). + */ + if (!preemptible()) return -EINVAL;
down(&hisi_hba->sem);