With PREEMPT_RCU, unless I use following check before calling
wait_event_interruptible() as follow:
if (!rcu_preempt_depth())
wait_event_interruptible(pu32hdd_wq, (hwdrvblkdev_rqst == 0));
I am getting the following stack dump and system hanging; any pointers
as to why could be the reason ?
[ 2.217625] ------------[ cut here ]------------
[ 2.218801] WARNING: CPU: 0 PID: 1 at kernel/rcu/tree_plugin.h:359 0x828000
[ 2.220019] CPU: 0 PID: 1 Comm: swapper Not tainted
5.13.0-00005-g730a9ddaf856-dirty #1
[ 2.221176] stacktrace:
[ 2.225111] 0x00820974 0x000247c2 show_stack+0x64/0x222
[ 2.226481] 0x00820998 0x005c1918 __dump_stack+0x22/0x2c
[ 2.227595] 0x0082099c 0x005c193e dump_stack+0x8/0x12
[ 2.228684] 0x008209a0 0x0002bdb4 __warn+0x10a/0x10e
[ 2.229841] 0x008209c4 0x0002be0a warn_slowpath_fmt+0x52/0x96
[ 2.231045] 0x008209e0 0x00090c7e rcu_note_context_switch+0x112/0x248
[ 2.232337] 0x008209f4 0x005e16d4 __schedule+0x54/0x698
[ 2.233705] 0x00820a28 0x005e1d98 schedule+0x80/0x128
[ 2.234962] 0x00820a34 0x005c0542 hwdrvblkdev_isbsy_+0x78/0x90
[ 2.236355] 0x00820a4c 0x005c02f2 hwdrvblkdev_isrdy+0x2e/0x52
[ 2.237671] 0x00820a50 0x005c0818 pu32hdd_do_request+0x1d0/0x56c
[ 2.238920] 0x00820a98 0x005c0be2 pu32hdd_queue_rq+0x2e/0xdc
[ 2.240087] 0x00820ab8 0x00378c56 __blk_mq_issue_directly+0x64/0x136
[ 2.241311] 0x00820ad8 0x00378e5e __blk_mq_try_issue_directly+0x136/0x16c
[ 2.242561] 0x00820af8 0x0037c002 blk_mq_try_issue_directly+0x36/0xac
[ 2.243821] 0x00820b0c 0x0037cb0c blk_mq_submit_bio+0x4c0/0x4e8
[ 2.245110] 0x00820b50 0x00369da8 __submit_bio_noacct_mq+0x10a/0x156
[ 2.246537] 0x00820b78 0x0036a676 submit_bio_noacct+0x92/0x9c
[ 2.247848] 0x00820b80 0x0036a756 submit_bio+0xd6/0x22e
[ 2.249245] 0x00820be0 0x00196ab8 submit_bh_wbc+0x234/0x428
[ 2.250418] 0x00820c08 0x0019b110 submit_bh+0xe/0x18
[ 2.251540] 0x00820c0c 0x0019e43e block_read_full_page+0x628/0x662
[ 2.252902] 0x00820c78 0x001a0956 blkdev_readpage+0x12/0x1c
[ 2.254101] 0x00820c7c 0x000c35f4 do_read_cache_page+0x178/0x4b4
[ 2.255488] 0x00820ca8 0x000c5e40 read_cache_page+0x10/0x1a
[ 2.256766] 0x00820cac 0x0038c67c read_part_sector+0xd2/0x220
[ 2.257992] 0x00820ccc 0x0038e1ac read_lba+0x1f8/0x238
[ 2.259217] 0x00820d08 0x0038fd4c find_valid_gpt+0x118/0x416
[ 2.260483] 0x00820d44 0x003900a2 efi_partition+0x58/0x54a
[ 2.261853] 0x00820dd0 0x0038b740 check_partition+0x1ac/0x2d4
[ 2.263054] 0x00820dec 0x0038c40a blk_add_partitions+0x84/0x224
[ 2.264277] 0x00820e08 0x001a3798 bdev_disk_changed+0xf6/0x254
[ 2.265581] 0x00820e30 0x001a39b4 __blkdev_get+0xbe/0x3b4
[ 2.266837] 0x00820e50 0x001a3e08 blkdev_get_by_dev+0x8c/0x1bc
[ 2.268121] 0x00820e70 0x00385ef8 disk_scan_partitions+0x14e/0x16c
[ 2.269503] 0x00820e80 0x003877d8 register_disk+0x15c/0x1e2
[ 2.270650] 0x00820e98 0x003879ca __device_add_disk+0x16c/0x2f4
[ 2.271842] 0x00820ec0 0x00387b5e device_add_disk+0xc/0x16
[ 2.273139] 0x00820f60 0x005e0128 kernel_init+0xe/0x128
[ 2.274375] 0x00820f6c 0x005e024a ret_from_exception+0x0/0x8
[ 2.276210] ---[ end trace 9d003344614aff8b ]---
