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List: dm-devel
Subject: [dm-devel] [PATCH 0/1] Handle NULL make_request_fn in generic_make_request()
From: Stefan Bader <stefan.bader () canonical ! com>
Date: 2020-01-23 9:17:12
Message-ID: 20200123091713.12623-1-stefan.bader () canonical ! com
[Download RAW message or body]
In ff36ab34583a "dm: remove request-based logic from make_request_fn wrapper",
device creation became a 2 stage process. In the first stage, the block
device is created which has a queue set up but no mapping function set.
This is done in the second stage, when the mapping table is supplied. At
that stage the device can become either multi-queue/request based or
doing the mapping on the bio level.
So right now, it is possible to crash the kernel by doing a
- dmsetup create --notable <name>
- mount /dev/dm-<minor> <somewhere>
While this may also need to be some fixing up in the device-
mapper codebase, it also should be handled from the block core as
allocating a queue can potentially be done separate from assigning a
mapping function.
There is already one check for not having set up a queue for a device,
so this just adds an additional check for make_request_fn being unset
before trying to further submit the requests.
-Stefan
Stefan Bader (1):
blk/core: Gracefully handle unset make_request_fn
block/blk-core.c | 7 +++++++
1 file changed, 7 insertions(+)
--
2.17.1
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