On Mon, Dec 19, 2016 at 12:16 PM, Jinpu Wang
<jinpu.wang@xxxxxxxxxxxxxxxx> wrote:
> Hi Neil,
>
> After apply the patch below, it paniced during boot in
> generic_make_request-> bio_list_pop.
> Looks related to you do bio_list_init(&bio_list_on_stack); again.
>> diff --git a/block/blk-core.c b/block/blk-core.c
>> index 14d7c0740dc0..3436b6fc3ef8 100644
>> --- a/block/blk-core.c
>> +++ b/block/blk-core.c
>> @@ -2036,10 +2036,31 @@ blk_qc_t generic_make_request(struct bio *bio)
>> struct request_queue *q = bdev_get_queue(bio->bi_bdev);
>>
>> if (likely(blk_queue_enter(q, false) == 0)) {
>> + struct bio_list hold;
>> + struct bio_list lower, same;
>> +
>> + /* Create a fresh bio_list for all subordinate requests */
>> + bio_list_merge(&hold, &bio_list_on_stack);
>> + bio_list_init(&bio_list_on_stack); ??? maybe init hold, and then merge bio_list_on_stack?
>> ret = q->make_request_fn(q, bio);
>>
>> blk_queue_exit(q);
>>
>> + /* sort new bios into those for a lower level
>> + * and those for the same level
>> + */
>> + bio_list_init(&lower);
>> + bio_list_init(&same);
>> + while ((bio = bio_list_pop(&bio_list_on_stack)) != NULL)
>> + if (q == bdev_get_queue(bio->bi_bdev))
>> + bio_list_add(&same, bio);
>> + else
>> + bio_list_add(&lower, bio);
>> + /* now assemble so we handle the lowest level first */
>> + bio_list_merge(&bio_list_on_stack, &lower);
>> + bio_list_merge(&bio_list_on_stack, &same);
>> + bio_list_merge(&bio_list_on_stack, &hold);
>> +
>> bio = bio_list_pop(current->bio_list);
>> } else {
>> struct bio *bio_next = bio_list_pop(current->bio_list);
>
>
Seems we don't need bio_list hold at all, lower and seem merge back to
bio_list_on_stack?
I'm currently testing patch below, so far so good.
diff --git a/block/blk-core.c b/block/blk-core.c
index e8d15d8..9c56cf7 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2064,10 +2064,24 @@ blk_qc_t generic_make_request(struct bio *bio)
struct request_queue *q = bdev_get_queue(bio->bi_bdev);
if (likely(blk_queue_enter(q, __GFP_DIRECT_RECLAIM) == 0)) {
+ struct bio_list lower, same;
ret = q->make_request_fn(q, bio);
blk_queue_exit(q);
+ /* sort new bios into those for a lower level
+ * and those for the same level
+ */
+ bio_list_init(&lower);
+ bio_list_init(&same);
+ while ((bio = bio_list_pop(&bio_list_on_stack)) != NULL)
+ if (q == bdev_get_queue(bio->bi_bdev))
+ bio_list_add(&same, bio);
+ else
+ bio_list_add(&lower, bio);
+ /* now assemble so we handle the lowest level first */
+ bio_list_merge(&bio_list_on_stack, &lower);
+ bio_list_merge(&bio_list_on_stack, &same);
bio = bio_list_pop(current->bio_list);
} else {
--
Jinpu Wang
Linux Kernel Developer
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D - 10405 Berlin
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