432061b3da
There's a XFS on dm-crypt deadlock, recursing back to itself due to the crypto subsystems use of GFP_KERNEL, reported here: https://bugzilla.kernel.org/show_bug.cgi?id=200835 * dm-crypt calls crypt_convert in xts mode * init_crypt from xts.c calls kmalloc(GFP_KERNEL) * kmalloc(GFP_KERNEL) recurses into the XFS filesystem, the filesystem tries to submit some bios and wait for them, causing a deadlock Fix this by updating both the DM crypt and integrity targets to no longer use the CRYPTO_TFM_REQ_MAY_SLEEP flag, which will change the crypto allocations from GFP_KERNEL to GFP_ATOMIC, therefore they can't recurse into a filesystem. A GFP_ATOMIC allocation can fail, but init_crypt() in xts.c handles the allocation failure gracefully - it will fall back to preallocated buffer if the allocation fails. The crypto API maintainer says that the crypto API only needs to allocate memory when dealing with unaligned buffers and therefore turning CRYPTO_TFM_REQ_MAY_SLEEP off is safe (see this discussion: https://www.redhat.com/archives/dm-devel/2018-August/msg00195.html ) Cc: stable@vger.kernel.org Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.