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Coly Li e599bfe543 bcache: only set BCACHE_DEV_WB_RUNNING when cached device attached
commit 1f0ffa6734 upstream.

When people set a writeback percent via sysfs file,
  /sys/block/bcache<N>/bcache/writeback_percent
current code directly sets BCACHE_DEV_WB_RUNNING to dc->disk.flags
and schedules kworker dc->writeback_rate_update.

If there is no cache set attached to, the writeback kernel thread is
not running indeed, running dc->writeback_rate_update does not make
sense and may cause NULL pointer deference when reference cache set
pointer inside update_writeback_rate().

This patch checks whether the cache set point (dc->disk.c) is NULL in
sysfs interface handler, and only set BCACHE_DEV_WB_RUNNING and
schedule dc->writeback_rate_update when dc->disk.c is not NULL (it
means the cache device is attached to a cache set).

This problem might be introduced from initial bcache commit, but
commit 3fd47bfe55 ("bcache: stop dc->writeback_rate_update properly")
changes part of the original code piece, so I add 'Fixes: 3fd47bfe55b0'
to indicate from which commit this patch can be applied.

Fixes: 3fd47bfe55 ("bcache: stop dc->writeback_rate_update properly")
Reported-by: Bjørn Forsman <bjorn.forsman@gmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Bjørn Forsman <bjorn.forsman@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-19 08:18:00 +02:00
arch ARM: exynos: Fix undefined instruction during Exynos5422 resume 2019-06-15 11:54:10 +02:00
block block, bfq: increase idling for weight-raised queues 2019-06-15 11:54:10 +02:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: ccm - fix incompatibility between "ccm" and "ccm_base" 2019-05-22 07:37:43 +02:00
Documentation tcp: add tcp_min_snd_mss sysctl 2019-06-17 19:51:56 +02:00
drivers bcache: only set BCACHE_DEV_WB_RUNNING when cached device attached 2019-06-19 08:18:00 +02:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs fs/ocfs2: fix race in ocfs2_dentry_attach_lock() 2019-06-19 08:18:00 +02:00
include tcp: add tcp_min_snd_mss sysctl 2019-06-17 19:51:56 +02:00
init initramfs: free initrd memory if opening /initrd.image fails 2019-06-15 11:54:01 +02:00
ipc ipc: prevent lockup on alloc_msg and free_msg 2019-06-15 11:54:00 +02:00
kernel ptrace: restore smp_rmb() in __ptrace_may_access() 2019-06-19 08:18:00 +02:00
lib test_firmware: Use correct snprintf() limit 2019-06-11 12:20:54 +02:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/vmscan.c: fix trying to reclaim unevictable LRU page 2019-06-19 08:18:00 +02:00
net tcp: enforce tcp_min_snd_mss in tcp_mtu_probing() 2019-06-17 19:51:56 +02:00
samples samples: mei: use /dev/mei0 instead of /dev/mei 2019-02-15 08:10:11 +01:00
scripts gcc-plugins: Fix build failures under Darwin host 2019-06-09 09:17:22 +02:00
security evm: check hash algorithm passed to init_desc() 2019-06-09 09:17:21 +02:00
sound ALSA: firewire-motu: fix destruction of data for isochronous resources 2019-06-19 08:17:59 +02:00
tools objtool: Don't use ignore flag for fake jumps 2019-06-15 11:54:03 +02:00
usr initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
virt KVM: s390: Do not report unusabled IDs via KVM_CAP_MAX_VCPU_ID 2019-06-09 09:17:18 +02:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS platform/x86: Add Intel AtomISP2 dummy / power-management driver 2019-04-20 09:16:02 +02:00
Makefile Linux 4.19.52 2019-06-17 19:51:57 +02:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -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.
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.