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authorJan Kara <jack@suse.cz>2021-06-23 12:36:34 +0300
committerJens Axboe <axboe@kernel.dk>2021-06-25 03:43:55 +0300
commitfd2ef39cc9a6b9c4c41864ac506906c52f94b06a (patch)
tree0d9ad0660f5947bccc862825bcdaf9f3bfd20789 /block/blk-mq.h
parenta921c655f2033dd1ce1379128efe881dda23ea37 (diff)
downloadlinux-fd2ef39cc9a6b9c4c41864ac506906c52f94b06a.tar.xz
blk: Fix lock inversion between ioc lock and bfqd lock
Lockdep complains about lock inversion between ioc->lock and bfqd->lock: bfqd -> ioc: put_io_context+0x33/0x90 -> ioc->lock grabbed blk_mq_free_request+0x51/0x140 blk_put_request+0xe/0x10 blk_attempt_req_merge+0x1d/0x30 elv_attempt_insert_merge+0x56/0xa0 blk_mq_sched_try_insert_merge+0x4b/0x60 bfq_insert_requests+0x9e/0x18c0 -> bfqd->lock grabbed blk_mq_sched_insert_requests+0xd6/0x2b0 blk_mq_flush_plug_list+0x154/0x280 blk_finish_plug+0x40/0x60 ext4_writepages+0x696/0x1320 do_writepages+0x1c/0x80 __filemap_fdatawrite_range+0xd7/0x120 sync_file_range+0xac/0xf0 ioc->bfqd: bfq_exit_icq+0xa3/0xe0 -> bfqd->lock grabbed put_io_context_active+0x78/0xb0 -> ioc->lock grabbed exit_io_context+0x48/0x50 do_exit+0x7e9/0xdd0 do_group_exit+0x54/0xc0 To avoid this inversion we change blk_mq_sched_try_insert_merge() to not free the merged request but rather leave that upto the caller similarly to blk_mq_sched_try_merge(). And in bfq_insert_requests() we make sure to free all the merged requests after dropping bfqd->lock. Fixes: aee69d78dec0 ("block, bfq: introduce the BFQ-v0 I/O scheduler as an extra scheduler") Reviewed-by: Ming Lei <ming.lei@redhat.com> Acked-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20210623093634.27879-3-jack@suse.cz Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/blk-mq.h')
-rw-r--r--block/blk-mq.h11
1 files changed, 11 insertions, 0 deletions
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 4b1ca7b7bbeb..d08779f77a26 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -302,6 +302,17 @@ static inline struct blk_plug *blk_mq_plug(struct request_queue *q,
return NULL;
}
+/* Free all requests on the list */
+static inline void blk_mq_free_requests(struct list_head *list)
+{
+ while (!list_empty(list)) {
+ struct request *rq = list_entry_rq(list->next);
+
+ list_del_init(&rq->queuelist);
+ blk_mq_free_request(rq);
+ }
+}
+
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