On 8/19/25 6:59 AM, Yu Kuai wrote: > From: Yu Kuai <yukuai3@xxxxxxxxxx> > > In the case user trigger tags grow by queue sysfs attribute nr_requests, > hctx->sched_tags will be freed directly and replaced with a new > allocated tags, see blk_mq_tag_update_depth(). > > The problem is that hctx->sched_tags is from elevator->et->tags, while > et->tags is still the freed tags, hence later elevator exist will try to nit: 's/exist/exit' > free the tags again, causing kernel panic. > > Fix this problem by replacing et->tags will new allocated tags as well. nit: 's/will/with' > > Noted there are still some long term problems that will require some > refactor to be fixed thoroughly[1]. > > [1] https://lore.kernel.org/all/20250815080216.410665-1-yukuai1@xxxxxxxxxxxxxxx/ > Fixes: f5a6604f7a44 ("block: fix lockdep warning caused by lock dependency in elv_iosched_store") > > Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx> > --- > block/blk-mq-tag.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c > index d880c50629d6..5cffa5668d0c 100644 > --- a/block/blk-mq-tag.c > +++ b/block/blk-mq-tag.c > @@ -622,6 +622,7 @@ int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx, > return -ENOMEM; > > blk_mq_free_map_and_rqs(set, *tagsptr, hctx->queue_num); > + hctx->queue->elevator->et->tags[hctx->queue_num] = new; > *tagsptr = new; > } else { > /* Except the above minor nitpicking this change looks good to me: Reviewed-by: Nilay Shroff<nilay@xxxxxxxxxxxxx>
