Messages in this thread | | | From | Miquel Raynal <> | Subject | Re: [PATCH] mtd: fix lock hierarchy in deregister_mtd_blktrans | Date | Fri, 6 Aug 2021 21:45:56 +0200 |
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On Sat, 2021-07-17 at 10:07:19 UTC, Desmond Cheong Zhi Xi wrote: > There is a lock hierarchy of major_names_lock --> mtd_table_mutex. One > existing chain is as follows: > > 1. major_names_lock --> loop_ctl_mutex (when blk_request_module calls > loop_probe) > > 2. loop_ctl_mutex --> bdev->bd_mutex (when loop_control_ioctl calls > loop_remove, which then calls del_gendisk) > > 3. bdev->bd_mutex --> mtd_table_mutex (when blkdev_get_by_dev calls > __blkdev_get, which then calls blktrans_open) > > Since unregister_blkdev grabs the major_names_lock, we need to call it > outside the critical section for mtd_table_mutex, otherwise we invert > the lock hierarchy. > > Reported-by: Hillf Danton <hdanton@sina.com> > Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/fixes, thanks.
Miquel
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