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Dongsheng Yang 7e59c506c3 bcache: check c->root with IS_ERR_OR_NULL() in mca_reserve()
In mca_reserve(c) macro, we are checking root whether is NULL or not.
But that's not enough, when we read the root node in run_cache_set(),
if we got an error in bch_btree_node_read_done(), we will return
ERR_PTR(-EIO) to c->root.

And then we will go continue to unregister, but before calling
unregister_shrinker(&c->shrink), there is a possibility to call
bch_mca_count(), and we would get a crash with call trace like that:

[ 2149.876008] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000b5
... ...
[ 2150.598931] Call trace:
[ 2150.606439]  bch_mca_count+0x58/0x98 [escache]
[ 2150.615866]  do_shrink_slab+0x54/0x310
[ 2150.624429]  shrink_slab+0x248/0x2d0
[ 2150.632633]  drop_slab_node+0x54/0x88
[ 2150.640746]  drop_slab+0x50/0x88
[ 2150.648228]  drop_caches_sysctl_handler+0xf0/0x118
[ 2150.657219]  proc_sys_call_handler.isra.18+0xb8/0x110
[ 2150.666342]  proc_sys_write+0x40/0x50
[ 2150.673889]  __vfs_write+0x48/0x90
[ 2150.681095]  vfs_write+0xac/0x1b8
[ 2150.688145]  ksys_write+0x6c/0xd0
[ 2150.695127]  __arm64_sys_write+0x24/0x30
[ 2150.702749]  el0_svc_handler+0xa0/0x128
[ 2150.710296]  el0_svc+0x8/0xc

Signed-off-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-10-02 14:25:29 -06:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-09-22 14:43:50 -07:00
block Merge branch 'for-5.10/block' into for-5.10/drivers 2020-09-24 13:44:39 -06:00
certs .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
crypto md/raid6: let async recovery function support different page offset 2020-09-24 16:44:44 -07:00
Documentation Merge branch 'for-5.10/block' into for-5.10/drivers 2020-09-24 13:44:39 -06:00
drivers bcache: check c->root with IS_ERR_OR_NULL() in mca_reserve() 2020-10-02 14:25:29 -06:00
fs Merge branch 'for-5.10/block' into for-5.10/drivers 2020-09-24 13:44:39 -06:00
include md/raid6: let async recovery function support different page offset 2020-09-24 16:44:44 -07:00
init bootconfig: init: make xbc_namebuf static 2020-09-18 22:17:05 -04:00
ipc ipc: adjust proc_ipc_sem_dointvec definition to match prototype 2020-09-05 12:14:29 -07:00
kernel Merge branch 'for-5.10/block' into for-5.10/drivers 2020-09-24 13:44:39 -06:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-09-22 14:43:50 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm Merge branch 'for-5.10/block' into for-5.10/drivers 2020-09-24 13:44:39 -06:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-09-22 14:43:50 -07:00
samples treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
scripts kconfig: qconf: revive help message in the info view 2020-09-20 12:58:54 +09:00
security device_cgroup RCU warning fix from Amol Grover <frextrite@gmail.com> 2020-09-15 16:26:57 -07:00
sound sound fixes for 5.9-rc6 2020-09-18 11:38:08 -07:00
tools Merge branch 'for-5.10/block' into for-5.10/drivers 2020-09-24 13:44:39 -06:00
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: fix memory leak in kvm_io_bus_unregister_dev() 2020-09-11 13:15:11 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2020-09-01 12:53:42 +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: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: Add ZSTD-compressed files 2020-07-31 11:50:49 +02:00
.mailmap mailmap: add older email addresses for Kees Cook 2020-09-19 13:13:38 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS CREDITS: Replace HTTP links with HTTPS ones 2020-07-23 14:53:58 -06:00
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 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2020-09-22 14:43:50 -07:00
Makefile Linux 5.9-rc6 2020-09-20 16:33:55 -07:00
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.