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| author | Shaohua Li <shaohua.li@intel.com> | 2011-12-16 14:00:22 +0100 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2011-12-16 14:00:22 +0100 |
| commit | 4a0b75c7d02c2bd46ed227d4ba5941ba8a0aba5d (patch) | |
| tree | a5a0c37a44c87227539ebc356178cc80435144d9 /block/cfq-iosched.c | |
| parent | f1f8cc94651738b418ba54c039df536303b91704 (diff) | |
| download | lwn-4a0b75c7d02c2bd46ed227d4ba5941ba8a0aba5d.tar.gz lwn-4a0b75c7d02c2bd46ed227d4ba5941ba8a0aba5d.zip | |
block, cfq: fix empty queue crash caused by request merge
All requests of a queue could be merged to other requests of other queue.
Such queue will not have request in it, but it's in service tree. This
will cause kernel oops.
I encounter a BUG_ON() in cfq_dispatch_request() with next patch, but the
issue should exist without the patch.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/cfq-iosched.c')
| -rw-r--r-- | block/cfq-iosched.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index f3b44c394e6d..163263ddd381 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -1656,6 +1656,8 @@ cfq_merged_requests(struct request_queue *q, struct request *rq, struct request *next) { struct cfq_queue *cfqq = RQ_CFQQ(rq); + struct cfq_data *cfqd = q->elevator->elevator_data; + /* * reposition in fifo if next is older than rq */ @@ -1670,6 +1672,16 @@ cfq_merged_requests(struct request_queue *q, struct request *rq, cfq_remove_request(next); cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg, rq_data_dir(next), rq_is_sync(next)); + + cfqq = RQ_CFQQ(next); + /* + * all requests of this queue are merged to other queues, delete it + * from the service tree. If it's the active_queue, + * cfq_dispatch_requests() will choose to expire it or do idle + */ + if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) && + cfqq != cfqd->active_queue) + cfq_del_cfqq_rr(cfqd, cfqq); } static int cfq_allow_merge(struct request_queue *q, struct request *rq, |