Now blk_cleanup_queue() can be called before calling
del_gendisk()[1], inside which hctx->ctxs is touched
from blk_mq_unregister_hctx(), but the variable has
been freed by blk_cleanup_queue() at that time.
So this patch moves freeing of hctx->ctxs into queue's
release handler for fixing the oops reported by Stefan.
Also ctx's kobject is embedded into each ctx pointed by
hctx->ctxs[], which shouldn't have been released so early.
[1], 6cd18e711dd8075 (block: destroy bdi before blockdev is
unregistered)
Reported-by: Stefan Seyfried <stefan.seyfried@xxxxxxxxxxxxxx>
Cc: NeilBrown <neilb@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: stable@xxxxxxxxxxxxxxx (v4.0)
Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
---
block/blk-mq.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index e68b71b..594eea0 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1600,6 +1600,7 @@ static int blk_mq_hctx_notify(void *data, unsigned long action,
return NOTIFY_OK;
}
+/* hctx->ctxs will be freed in queue's release handler */
static void blk_mq_exit_hctx(struct request_queue *q,
struct blk_mq_tag_set *set,
struct blk_mq_hw_ctx *hctx, unsigned int hctx_idx)
@@ -1618,7 +1619,6 @@ static void blk_mq_exit_hctx(struct request_queue *q,
blk_mq_unregister_cpu_notifier(&hctx->cpu_notifier);
blk_free_flush_queue(hctx->fq);
- kfree(hctx->ctxs);
blk_mq_free_bitmap(&hctx->ctx_map);
}
@@ -1891,8 +1891,12 @@ void blk_mq_release(struct request_queue *q)
unsigned int i;
/* hctx kobj stays in hctx */
- queue_for_each_hw_ctx(q, hctx, i)
+ queue_for_each_hw_ctx(q, hctx, i) {
+ if (!hctx)
+ continue;
+ kfree(hctx->ctxs);
kfree(hctx);
+ }
kfree(q->queue_hw_ctx);
--
1.9.1
--
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