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Heinz Mauelshagen 0cd2d2577a dm raid: fix inconclusive reshape layout on fast raid4/5/6 table reload sequences
commit f99a8e4373 upstream.

If fast table reloads occur during an ongoing reshape of raid4/5/6
devices the target may race reading a superblock vs the the MD resync
thread; causing an inconclusive reshape state to be read in its
constructor.

lvm2 test lvconvert-raid-reshape-stripes-load-reload.sh can cause
BUG_ON() to trigger in md_run(), e.g.:
"kernel BUG at drivers/md/raid5.c:7567!".

Scenario triggering the bug:

1. the MD sync thread calls end_reshape() from raid5_sync_request()
   when done reshaping. However end_reshape() _only_ updates the
   reshape position to MaxSector keeping the changed layout
   configuration though (i.e. any delta disks, chunk sector or RAID
   algorithm changes). That inconclusive configuration is stored in
   the superblock.

2. dm-raid constructs a mapping, loading named inconsistent superblock
   as of step 1 before step 3 is able to finish resetting the reshape
   state completely, and calls md_run() which leads to mentioned bug
   in raid5.c.

3. the MD RAID personality's finish_reshape() is called; which resets
   the reshape information on chunk sectors, delta disks, etc. This
   explains why the bug is rarely seen on multi-core machines, as MD's
   finish_reshape() superblock update races with the dm-raid
   constructor's superblock load in step 2.

Fix identifies inconclusive superblock content in the dm-raid
constructor and resets it before calling md_run(), factoring out
identifying checks into rs_is_layout_change() to share in existing
rs_reshape_requested() and new rs_reset_inclonclusive_reshape(). Also
enhance a comment and remove an empty line.

Cc: stable@vger.kernel.org
Signed-off-by: Heinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-05-11 14:47:36 +02:00
arch crypto: arm/curve25519 - Move '.fpu' after '.arch' 2021-05-11 14:47:35 +02:00
block block: return -EBUSY when there are open partitions in blkdev_reread_part 2021-04-28 13:39:59 +02:00
certs certs: Fix blacklist flag type confusion 2021-03-04 11:37:59 +01:00
crypto crypto: rng - fix crypto_rng_reset() refcounting when !CRYPTO_STATS 2021-05-11 14:47:35 +02:00
Documentation dt-bindings: net: ethernet-controller: fix typo in NVMEM 2021-04-14 08:42:12 +02:00
drivers dm raid: fix inconclusive reshape layout on fast raid4/5/6 table reload sequences 2021-05-11 14:47:36 +02:00
fs jffs2: Hook up splice_write callback 2021-05-11 14:47:35 +02:00
include perf: Rework perf_event_exit_event() 2021-05-11 14:47:31 +02:00
init init/Kconfig: make COMPILE_TEST depend on HAS_IOMEM 2021-04-10 13:36:11 +02:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2020-09-05 12:14:29 -07:00
kernel kcsan, debugfs: Move debugfs file creation out of early init 2021-05-11 14:47:33 +02:00
lib dyndbg: fix parsing file query without a line-range suffix 2021-05-11 14:47:11 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm: ptdump: fix build failure 2021-04-21 13:00:57 +02:00
net openvswitch: fix stack OOB read while fragmenting IPv4 packets 2021-05-11 14:47:34 +02:00
samples samples, bpf: Add missing munmap in xdpsock 2021-03-17 17:06:12 +01:00
scripts kasan: fix hwasan build for gcc 2021-04-28 13:40:02 +02:00
security KEYS: trusted: Fix TPM reservation for seal/unseal 2021-04-28 13:39:59 +02:00
sound ALSA: hda/realtek: Add quirk for Intel Clevo PCx0Dx 2021-05-11 14:47:33 +02:00
tools tools/power/turbostat: Fix turbostat for AMD Zen CPUs 2021-05-11 14:47:33 +02:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: Use kvm_pfn_t for local PFN variable in hva_to_pfn_remapped() 2021-02-26 10:13:01 +01:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: docs: ignore sphinx_*/ directories 2020-09-10 10:44:31 -06:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: move the staging subsystem to lists.linux.dev 2021-03-25 09:04:18 +01:00
Makefile Makefile: Move -Wno-unused-but-set-variable out of GCC only block 2021-05-11 14:47:33 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.