> Hi Neil, > > I found a old mail thread below > http://www.spinics.net/lists/raid/msg52792.html > > Likely Alex is trying to fix same bug, right? > in one reply you suggested to modify the call in make_request > > @@ -1207,7 +1207,8 @@ read_again: > sectors_handled; > goto read_again; > } else > - generic_make_request(read_bio); > + reschedule_retry(r1_bio); > return; > } > > > I append above change, it looks fix the bug, I've run same tests over > one hour, no hung task anymore. > > Do you think this is right fix? Do we still need the change you > suggested with punt_bios_to_rescuer? I don't really like that fix. I suspect it would probably hurt performance. I'd prefer to fix generic_make_request() to process queued requests in a more sensible order. Can you please try the following (with all other patches removed)? Thanks, NeilBrown 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); 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);
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