[PATCH 1/1] block: print warning when invalid domain set to ioprio

[zhaoyang.huang]

From: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>

Since few caller check IOPRIO_PRIO_VALUE's return value and bio_set_prio
is a open macro to set bio->ioprio directly.It is confused for the developer
who run across kernel panic[1] but can find nothing in previous kernel log.
Add a pr_err here to dump the information.

[1]
Here is the kernel panic I run across which caused by a out of bounds check
introduced by CONFIG_FOTIFY_SOURCE.

[exception_serialno]:
[exception_kernel_version]:
[exception_reboot_reason]: kernel_crash
[exception_panic_reason]: UBSAN: array index out of bounds: Fatal exception
[exception_time]: 1970-01-01_08-00-23
[exception_file_info]: not-bugon
[exception_task_id]: 409
[exception_task_family]: [f2fs_ckpt-254:4, 409][kthreadd, 2]
[exception_pc_symbol]: [<ffffffc080736974>] dd_request_merge+0x100/0x110
[exception_stack_info]: [<ffffffc07a27e274>] get_exception_stack_info+0x124/0x2d8 [sysdump]gc
[<ffffffc07a27e670>] prepare_exception_info+0x158/0x1d4 [sysdump]gc
[<ffffffc07a280128>] sysdump_panic_event+0x5d8/0x748 [sysdump]gc
[<ffffffc08016a508>] notifier_call_chain+0x98/0x17cgc
[<ffffffc08016a9b4>] atomic_notifier_call_chain+0x44/0x68gc
[<ffffffc0810f0eb4>] panic+0x194/0x37cgc
[<ffffffc0800a638c>] die+0x300/0x310gc
[<ffffffc0800a77e8>] ubsan_handler+0x34/0x4cgc
[<ffffffc0800960a8>] brk_handler+0x9c/0x11cgc
[<ffffffc0800bf998>] do_debug_exception+0xb0/0x140gc
[<ffffffc0810f8bf0>] el1_dbg+0x58/0x74gc
[<ffffffc0810f89f4>] el1h_64_sync_handler+0x3c/0x90gc
[<ffffffc080091298>] el1h_64_sync+0x68/0x6cgc
[<ffffffc080736974>] dd_request_merge+0x100/0x110gc   //out of bound
here caused by the value of class transferred from ioprio
[<ffffffc080707f28>] elv_merge+0x248/0x270gc
[<ffffffc0807146e8>] blk_mq_sched_try_merge+0x4c/0x20cgc
[<ffffffc080736824>] dd_bio_merge+0x64/0xb4gc
[<ffffffc080723e3c>] blk_mq_sched_bio_merge+0x68/0x144gc
[<ffffffc08071b944>] blk_mq_submit_bio+0x2e8/0x6c0gc
[<ffffffc08070dd3c>] __submit_bio+0xbc/0x1b0gc
[<ffffffc08070c440>] submit_bio_noacct_nocheck+0xe4/0x2f0gc
[<ffffffc08070c8e4>] submit_bio_noacct+0x298/0x3d8gc
[<ffffffc08070caf8>] submit_bio+0xd4/0xf0gc
[<ffffffc080642644>] f2fs_submit_write_bio+0xcc/0x49cgc
[<ffffffc0806442d4>] __submit_merged_bio+0x48/0x13cgc
[<ffffffc080641de4>] __submit_merged_write_cond+0x18c/0x1f8gc
[<ffffffc080641c4c>] f2fs_submit_merged_write+0x2c/0x38
[<ffffffc080655724>] f2fs_sync_node_pages+0x6e0/0x740gc
[<ffffffc08063946c>] f2fs_write_checkpoint+0x4c0/0x97cgc
[<ffffffc08063b37c>] __checkpoint_and_complete_reqs+0x88/0x248gc
[<ffffffc08063ad70>] issue_checkpoint_thread+0x94/0xf4gc
[<ffffffc080167c20>] kthread+0x110/0x1b8gc

Signed-off-by: Zhaoyang Huang <zhaoyang.huang@xxxxxxxxxx>
---
 include/uapi/linux/ioprio.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/ioprio.h b/include/uapi/linux/ioprio.h
index bee2bdb0eedb..73c420a0df72 100644
--- a/include/uapi/linux/ioprio.h
+++ b/include/uapi/linux/ioprio.h
@@ -112,8 +112,11 @@ static __always_inline __u16 ioprio_value(int prioclass, int priolevel,
 {
 	if (IOPRIO_BAD_VALUE(prioclass, IOPRIO_NR_CLASSES) ||
 	    IOPRIO_BAD_VALUE(priolevel, IOPRIO_NR_LEVELS) ||
-	    IOPRIO_BAD_VALUE(priohint, IOPRIO_NR_HINTS))
+	    IOPRIO_BAD_VALUE(priohint, IOPRIO_NR_HINTS)) {
+		pr_err("%s: get a invalid domain in class %d, level %d, hint %d\n",
+			__func__, prioclass, priolevel, priohint);
 		return IOPRIO_CLASS_INVALID << IOPRIO_CLASS_SHIFT;
+	}
 
 	return (prioclass << IOPRIO_CLASS_SHIFT) |
 		(priohint << IOPRIO_HINT_SHIFT) | priolevel;
-- 
2.25.1