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[ Upstream commit 432061b3da64e488be3403124a72a9250bbe96d4 ] 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> Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.