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Chen Wandun de1ccfb648 swapfile: fix soft lockup in scan_swap_map_slots
A softlockup occurs in scan free swap slot under huge memory pressure. 
The test scenario is: 64 CPU cores, 64GB memory, and 28 zram devices, the
disksize of each zram device is 50MB.

LATENCY_LIMIT is used to prevent softlockups in scan_swap_map_slots(), but
the real loop number would more than LATENCY_LIMIT because of "goto checks
and goto scan" repeatly without decreasing latency limit.

In order to fix it, decrease latency_ration in advance.

There is also a suspicious place that will cause softlockups in
get_swap_pages().  In this function, the "goto start_over" may result in
continuous scanning of the swap partition.  If there is no cond_sched in
scan_swap_map_slots(), it would cause a softlockup (I am not sure about
this).

WARN: soft lockup - CPU#11 stuck for 11s! [kswapd0:466]
CPU: 11 PID: 466 Comm: kswapd@ Kdump: loaded Tainted: G
dump backtrace+0x0/0x1le4
show stack+0x20/@x2c
dump_stack+0xd8/0x140
watchdog print_info+0x48/0x54
watchdog_process_before_softlockup+0x98/0xa0
watchdog_timer_fn+0xlac/0x2d0
hrtimer_rum_queues+0xb0/0x130
hrtimer_interrupt+0x13c/0x3c0
arch_timer_handler_virt+0x3c/0x50
handLe_percpu_devid_irq+0x90/0x1f4
handle domain irq+0x84/0x100
gic_handle_irq+0x88/0x2b0
e11 ira+0xhB/Bx140
scan_swap_map_slots+0x678/0x890
get_swap_pages+0x29c/0x440
get_swap_page+0x120/0x2e0
add_to_swap+UX2U/0XyC
shrink_page_list+0x5d0/0x152c
shrink_inactive_list+0xl6c/Bx500
shrink_lruvec+0x270/0x304

WARN: soft lockup - CPU#32 stuck for 11s! [stress-ng:309915]
watchdog_timer_fn+0x1ac/0x2d0
__run_hrtimer+0x98/0x2a0
__hrtimer_run_queues+0xb0/0x130
hrtimer_interrupt+0x13c/0x3c0
arch_timer_handler_virt+0x3c/0x50
handle_percpu_devid_irq+0x90/0x1f4
__handle_domain_irq+0x84/0x100
gic_handle_irq+0x88/0x2b0
el1_irq+0xb8/0x140
get_swap_pages+0x1e8/0x440
get_swap_page+0x1c8/0x2e0
add_to_swap+0x20/0x9c
shrink_page_list+0x5d0/0x152c
reclaim_pages+0x160/0x310
madvise_cold_or_pageout_pte_range+0x7bc/0xe3c
walk_pmd_range.isra.0+0xac/0x22c
walk_pud_range+0xfc/0x1c0
walk_pgd_range+0x158/0x1b0
__walk_page_range+0x64/0x100
walk_page_range+0x104/0x150

Link: https://lkml.kernel.org/r/20221118133850.3360369-1-chenwandun@huawei.com
Fixes: 048c27fd72 ("[PATCH] swap: scan_swap_map latency breaks")
Signed-off-by: Chen Wandun <chenwandun@huawei.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Cc: <xialonglong1@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-11-22 18:50:44 -08:00
arch arch/x86/mm/hugetlbpage.c: pud_huge() returns 0 when using 2-level paging 2022-11-08 15:57:25 -08:00
block block-6.1-2022-11-05 2022-11-05 09:02:28 -07:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto treewide: use get_random_bytes() when possible 2022-10-11 17:42:58 -06:00
Documentation docs: kmsan: fix formatting of "Example report" 2022-11-08 15:57:25 -08:00
drivers cxl fixes for 6.1-rc4 2022-11-06 13:09:52 -08:00
fs proc/meminfo: fix spacing in SecPageTables 2022-11-22 18:50:44 -08:00
include kbuild: fix -Wimplicit-function-declaration in license_is_gpl_compatible 2022-11-22 18:50:43 -08:00
init init: Kconfig: fix spelling mistake "satify" -> "satisfy" 2022-10-20 21:27:22 -07:00
io_uring io_uring: unlock if __io_run_local_work locked inside 2022-10-27 09:52:12 -06:00
ipc ipc/shm: call underlying open/close vm_ops 2022-11-22 18:50:42 -08:00
kernel gcov: clang: fix the buffer overflow issue 2022-11-22 18:50:41 -08:00
lib maple_tree: don't set a new maximum on the node when not reusing nodes 2022-11-08 15:57:25 -08:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm swapfile: fix soft lockup in scan_swap_map_slots 2022-11-22 18:50:44 -08:00
net Networking fixes for 6.1-rc4, including fixes from bluetooth and 2022-11-03 10:51:59 -07:00
rust Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
samples VFIO updates for v6.1-rc1 2022-10-12 14:46:48 -07:00
scripts kconfig: fix segmentation fault in menuconfig search 2022-11-02 17:32:05 +09:00
security lsm/stable-6.1 PR 20221031 2022-10-31 12:09:42 -07:00
sound ALSA: aoa: Fix I2S device accounting 2022-10-27 08:53:08 +02:00
tools maple_tree: reorganize testing to restore module testing 2022-11-08 15:57:22 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt Merge tag 'kvmarm-fixes-6.1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD 2022-11-06 03:30:49 -05:00
.clang-format PCI/DOE: Add DOE mailbox support functions 2022-07-19 15:38:04 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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 dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap mailmap: update email address for Satya Priya 2022-11-22 18:50:43 -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 drm for 5.20/6.0 2022-08-03 19:52:08 -07:00
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 MAINTAINERS: update Alex Hung's email address 2022-11-22 18:50:43 -08:00
Makefile Linux 6.1-rc4 2022-11-06 15:07:11 -08:00
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.