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Linux kernel source tree for SHARP Brain series (PW-SH1 or later)
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Muchun Song 5c93fc4668 writeback: fix obtain a reference to a freeing memcg css 
[ Upstream commit 8b0ed8443ae6458786580d36b7d5f8125535c5d4 ]

The caller of wb_get_create() should pin the memcg, because
wb_get_create() relies on this guarantee. The rcu read lock
only can guarantee that the memcg css returned by css_from_id()
cannot be released, but the reference of the memcg can be zero.

  rcu_read_lock()
  memcg_css = css_from_id()
  wb_get_create(memcg_css)
      cgwb_create(memcg_css)
          // css_get can change the ref counter from 0 back to 1
          css_get(memcg_css)
  rcu_read_unlock()

Fix it by holding a reference to the css before calling
wb_get_create(). This is not a problem I encountered in the
real world. Just the result of a code review.

Fixes: 682aa8e1a6 ("writeback: implement unlocked_inode_to_wb transaction and use it for stat updates")
Link: https://lore.kernel.org/r/20210402091145.80635-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
 		2021-07-14 16:53:35 +02:00
Documentation clocksource: Retry clock read if long delays detected 2021-07-14 16:53:18 +02:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch KVM: nVMX: Ensure 64-bit shift when checking VMFUNC bitmap 2021-07-14 16:53:23 +02:00
block blk-wbt: make sure throttle is enabled properly 2021-07-14 16:53:25 +02:00
certs certs: Move load_system_certificate_list to a common function 2021-06-30 08:47:55 -04:00
crypto crypto: shash - avoid comparing pointers to exported functions under CFI 2021-07-14 16:53:13 +02:00
drivers clk: si5341: Update initialization magic 2021-07-14 16:53:35 +02:00
fs writeback: fix obtain a reference to a freeing memcg css 2021-07-14 16:53:35 +02:00
include net: sched: add barrier to ensure correct ordering for lockless qdisc 2021-07-14 16:53:31 +02:00
init kbuild: add CONFIG_LD_IS_LLD 2021-06-30 08:47:44 -04:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel sched/uclamp: Fix uclamp_tg_restrict() 2021-07-14 16:53:24 +02:00
lib lib: vsprintf: Fix handling of number field widths in vsscanf 2021-07-14 16:53:16 +02:00
mm mm, futex: fix shared futex pgoff on shmem huge page 2021-06-30 08:47:55 -04:00
net Bluetooth: Fix handling of HCI_LE_Advertising_Set_Terminated event 2021-07-14 16:53:34 +02:00
samples samples/bpf: Fix the error return code of xdp_redirect's main() 2021-07-14 16:53:30 +02:00
scripts kbuild: Fix objtool dependency for 'OBJECT_FILES_NON_STANDARD_<obj> := n' 2021-07-14 16:53:20 +02:00
security evm: fix writing <securityfs>/evm overflow 2021-07-14 16:53:21 +02:00
sound ALSA: hda/realtek: Apply LED fixup for HP Dragonfly G1, too 2021-07-14 16:52:59 +02:00
tools tc-testing: fix list handling 2021-07-14 16:53:31 +02:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt KVM: do not allow mapping valid but non-reference-counted pages 2021-06-30 08:47:50 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Documentation/llvm: add documentation on building w/ Clang/LLVM 2020-08-26 10:40:46 +02:00
Makefile Makefile: fix GDB warning with CONFIG_RELR 2021-07-14 16:53:12 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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.