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Tejun Heo d527ab46d1 cgroup,writeback: don't switch wbs immediately on dead wbs if the memcg is dead 
commit 65de03e251 upstream.

cgroup writeback tries to refresh the associated wb immediately if the
current wb is dead.  This is to avoid keeping issuing IOs on the stale
wb after memcg - blkcg association has changed (ie. when blkcg got
disabled / enabled higher up in the hierarchy).

Unfortunately, the logic gets triggered spuriously on inodes which are
associated with dead cgroups.  When the logic is triggered on dead
cgroups, the attempt fails only after doing quite a bit of work
allocating and initializing a new wb.

While c3aab9a0bd ("mm/filemap.c: don't initiate writeback if mapping
has no dirty pages") alleviated the issue significantly as it now only
triggers when the inode has dirty pages.  However, the condition can
still be triggered before the inode is switched to a different cgroup
and the logic simply doesn't make sense.

Skip the immediate switching if the associated memcg is dying.

This is a simplified version of the following two patches:

 * https://lore.kernel.org/linux-mm/20190513183053.GA73423@dennisz-mbp/
 * http://lkml.kernel.org/r/156355839560.2063.5265687291430814589.stgit@buzz

Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Fixes: e8a7abf5a5 ("writeback: disassociate inodes from dying bdi_writebacks")
Acked-by: Dennis Zhou <dennis@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2019-11-12 19:18:47 +01:00
Documentation sched/fair: Fix low cpu usage with high throttling by removing expiration of cpu-local slices 2019-11-12 19:18:29 +01:00
arch x86/apic/32: Avoid bogus LDR warnings 2019-11-12 19:18:46 +01:00
block blk-mq: move cancel of requeue_work to the front of blk_exit_queue 2019-10-05 12:47:37 +02:00
certs Replace magic for trusting the secondary keyring with #define 2018-09-09 19:55:54 +02:00
crypto crypto: skcipher - Unmap pages after an external error 2019-10-11 18:18:32 +02:00
drivers can: flexcan: disable completely the ECC mechanism 2019-11-12 19:18:46 +01:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs cgroup,writeback: don't switch wbs immediately on dead wbs if the memcg is dead 2019-11-12 19:18:47 +01:00
include ipvs: move old_secure_tcp into struct netns_ipvs 2019-11-12 19:18:38 +01:00
init init: initialize jump labels before command line option parsing 2019-05-16 19:42:23 +02:00
ipc ipc/mqueue.c: only perform resource calculation if user valid 2019-08-06 19:05:24 +02:00
kernel sched/fair: Fix -Wunused-but-set-variable warnings 2019-11-12 19:18:29 +01:00
lib lib/scatterlist: Introduce sgl_alloc() and sgl_free() 2019-11-12 19:18:30 +01:00
mm mm/filemap.c: don't initiate writeback if mapping has no dirty pages 2019-11-12 19:18:46 +01:00
net ipvs: move old_secure_tcp into struct netns_ipvs 2019-11-12 19:18:38 +01:00
samples samples, bpf: fix to change the buffer size for read() 2019-07-21 09:04:17 +02:00
scripts scripts/setlocalversion: Improve -dirty check with git-status --no-optional-locks 2019-11-06 12:42:55 +01:00
security ima: always return negative code for error 2019-10-11 18:18:37 +02:00
sound ASoC: davinci-mcasp: Fix an error handling path in 'davinci_mcasp_probe()' 2019-11-12 19:18:26 +01:00
tools perf tools: Fix time sorting 2019-11-12 19:18:03 +01:00
usr kbuild: clean compressed initramfs image 2019-10-07 18:55:14 +02:00
virt KVM: coalesced_mmio: add bounds checking 2019-09-21 07:15:28 +02:00
.cocciconfig
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.get_maintainer.ignore
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.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: rpm-pkg: keep spec file until make mrproper 2018-02-13 10:19:46 +01:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING
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CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS USB: rio500: Remove Rio 500 kernel driver 2019-10-17 13:43:20 -07:00
Makefile Linux 4.14.153 2019-11-10 11:25:43 +01:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README 

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.