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v5.11 changes the blkdev lookup mechanism completely since commit22ae8ce8b8("block: simplify bdev/disk lookup in blkdev_get"), and small part of the change is to unhash part bdev inode when deleting partition. Turns out this kind of change does fix one nasty issue in case of BLOCK_EXT_MAJOR: 1) when one partition is deleted & closed, disk_put_part() is always called before bdput(bdev), see blkdev_put(); so the part's devt can be freed & re-used before the inode is dropped 2) then new partition with same devt can be created just before the inode in 1) is dropped, then the old inode/bdev structurein 1) is re-used for this new partition, this way causes use-after-free and kernel panic. It isn't possible to backport the whole big patchset of "merge struct block_device and struct hd_struct v4" for addressing this issue. https://lore.kernel.org/linux-block/20201128161510.347752-1-hch@lst.de/ So fixes it by unhashing part bdev in delete_partition(), and this way is actually aligned with v5.11+'s behavior. Backported from the following 5.10.y commit:5f2f775605("block: unhash blkdev part inode when the part is deleted") Reported-by: Shiwei Cui <cuishw@inspur.com> Tested-by: Shiwei Cui <cuishw@inspur.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.