When device-mapper adapted for multi-queue functionality, they also re-organized the way the make-request function was set. Before, this happened when the device-mapper logical device was created. Now it is done once the mapping table gets loaded the first time (this also decides whether the block device is request or bio based). However in generic_make_request(), the request function gets used without further checks and this happens if one tries to mount such a partially set up device. This can easily be reproduced with the following steps: - dmsetup create -n test - mount /dev/dm-<#> /mnt This maybe is something which also should be fixed up in device- mapper. But given there is already a check for an unset queue pointer and potentially there could be other drivers which do or might do the same, it sounds like a good move to add another check to generic_make_request_checks() and to bail out if the request function has not been set, yet. BugLink: https://bugs.launchpad.net/bugs/1860231 Fixes: ff36ab34583a ("dm: remove request-based logic from make_request_fn wrapper") Signed-off-by: Stefan Bader <stefan.bader@xxxxxxxxxxxxx> --- block/blk-core.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/block/blk-core.c b/block/blk-core.c index 1075aaff606d..adcd042edd2d 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -884,6 +884,13 @@ generic_make_request_checks(struct bio *bio) bio_devname(bio, b), (long long)bio->bi_iter.bi_sector); goto end_io; } + if (unlikely(!q->make_request_fn)) { + printk(KERN_ERR + "generic_make_request: Trying to access " + "block-device without request function: %s\n", + bio_devname(bio, b)); + goto end_io; + } /* * Non-mq queues do not honor REQ_NOWAIT, so complete a bio -- 2.17.1
