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Li Nan 72c215ed87 md/raid10: fix task hung in raid10d 
commit fe630de009 ("md/raid10: avoid deadlock on recovery.") allowed
normal io and sync io to exist at the same time. Task hung will occur as
below:

T1                      T2		T3		T4
raid10d
 handle_read_error
  allow_barrier
   conf->nr_pending--
    -> 0
                        //submit sync io
                        raid10_sync_request
                         raise_barrier
			  ->will not be blocked
			  ...
			//submit to drivers
  raid10_read_request
   wait_barrier
    conf->nr_pending++
     -> 1
					//retry read fail
					raid10_end_read_request
					 reschedule_retry
					  add to retry_list
					  conf->nr_queued++
					   -> 1
							//sync io fail
							end_sync_read
							 __end_sync_read
							  reschedule_retry
							   add to retry_list
					                    conf->nr_queued++
							     -> 2
 ...
 handle_read_error
 get form retry_list
 conf->nr_queued--
  freeze_array
   wait nr_pending == nr_queued+1
        ->1	      ->2
   //task hung

retry read and sync io will be added to retry_list(nr_queued->2) if they
fails. raid10d() called handle_read_error() and hung in freeze_array().
nr_queued will not decrease because raid10d is blocked, nr_pending will
not increase because conf->barrier is not released.

Fix it by moving allow_barrier() after raid10_read_request().
raise_barrier() will wait for nr_waiting to become 0. Therefore, sync io
and regular io will not be issued at the same time.

Also remove the check of nr_queued in stop_waiting_barrier. It can be 0
but don't need to be blocking. Remove the check for MD_RECOVERY_RUNNING as
the check is redundent.

Fixes: fe630de009 ("md/raid10: avoid deadlock on recovery.")
Signed-off-by: Li Nan <linan122@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20230222041000.3341651-2-linan666@huaweicloud.com
2023-04-13 22:20:23 -07:00
arch s390/dasd: add autoquiesce feature 2023-04-11 19:53:08 -06:00
block blk-mq: remove __blk_mq_run_hw_queue 2023-04-13 06:58:02 -06:00
certs Kbuild updates for v6.3 2023-02-26 11:53:25 -08:00
crypto Networking changes for 6.3. 2023-02-21 18:24:12 -08:00
Documentation block: null_blk: make fault-injection dynamically configurable per device 2023-04-13 07:38:55 -06:00
drivers md/raid10: fix task hung in raid10d 2023-04-13 22:20:23 -07:00
fs Fixes for 6.3-rc1: 2023-03-12 09:47:08 -07:00
include fault-inject: allow configuration via configfs 2023-04-13 07:38:54 -06:00
init Kbuild updates for v6.3 2023-02-26 11:53:25 -08:00
io_uring blk-mq: remove hybrid polling 2023-03-20 15:30:03 -06:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel kernel.fork.v6.3-rc2 2023-03-12 09:04:28 -07:00
lib fault-inject: allow configuration via configfs 2023-04-13 07:38:54 -06:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: avoid gcc complaint about pointer casting 2023-03-04 14:03:27 -08:00
net wifi: cfg80211: Partial revert "wifi: cfg80211: Fix use after free for wext" 2023-03-12 16:21:59 -07:00
rust Rust fixes for 6.3-rc1 2023-03-03 14:51:15 -08:00
samples LoongArch changes for v6.3 2023-03-01 09:27:00 -08:00
scripts Remove Intel compiler support 2023-03-05 10:49:37 -08:00
security capability: just use a 'u64' instead of a 'u32[2]' array 2023-03-01 10:01:22 -08:00
sound sound fixes for 6.3-rc1 2023-03-04 10:53:59 -08:00
tools kernel.fork.v6.3-rc2 2023-03-12 09:04:28 -07:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM/riscv changes for 6.3 2023-02-15 12:33:28 -05:00
.clang-format cpumask: re-introduce constant-sized cpumask optimizations 2023-03-05 14:30:34 -08:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore .gitignore: ignore *.cover and *.mbx 2023-02-05 18:51:22 +09:00
.mailmap drm fixes for 6.3-rc2 2023-03-10 08:57:46 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS There is no particular theme here - mainly quick hits all over the tree. 2023-02-23 17:55:40 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Staging driver fixes and removal for 6.3-rc2 2023-03-12 09:17:30 -07:00
Makefile Linux 6.3-rc2 2023-03-12 16:36:44 -07:00
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.