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Filename Latest commit message Latest commit date
Shakeel Butt dffcac2cb8 mm/vmscan.c: prevent useless kswapd loops
In production we have noticed hard lockups on large machines running
large jobs due to kswaps hoarding lru lock within isolate_lru_pages when
sc->reclaim_idx is 0 which is a small zone.  The lru was couple hundred
GiBs and the condition (page_zonenum(page) > sc->reclaim_idx) in
isolate_lru_pages() was basically skipping GiBs of pages while holding
the LRU spinlock with interrupt disabled.

On further inspection, it seems like there are two issues:

(1) If kswapd on the return from balance_pgdat() could not sleep (i.e.
    node is still unbalanced), the classzone_idx is unintentionally set
    to 0 and the whole reclaim cycle of kswapd will try to reclaim only
    the lowest and smallest zone while traversing the whole memory.

(2) Fundamentally isolate_lru_pages() is really bad when the
    allocation has woken kswapd for a smaller zone on a very large machine
    running very large jobs.  It can hoard the LRU spinlock while skipping
    over 100s of GiBs of pages.

This patch only fixes (1).  (2) needs a more fundamental solution.  To
fix (1), in the kswapd context, if pgdat->kswapd_classzone_idx is
invalid use the classzone_idx of the previous kswapd loop otherwise use
the one the waker has requested.

Link: http://lkml.kernel.org/r/20190701201847.251028-1-shakeelb@google.com
Fixes: e716f2eb24 ("mm, vmscan: prevent kswapd sleeping prematurely due to mismatched classzone_idx")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Yang Shi <yang.shi@linux.alibaba.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-05 11:12:07 +09:00
arch This includes three fixes: 2019-07-04 10:26:17 +09:00
block block, bfq: fix operator in BFQQ_TOTALLY_SEEKY 2019-06-25 11:38:08 -06:00
certs
crypto treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
Documentation dt-bindings: riscv: resolve 'make dt_binding_check' warnings 2019-06-26 10:28:53 -07:00
drivers A single fixup for the SPI CS gpios that regressed 2019-07-04 09:59:08 +09:00
fs fs/userfaultfd.c: disable irqs for fault_pending and event locks 2019-07-05 11:12:07 +09:00
include Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-06-29 19:39:17 +08:00
init initramfs: fix populate_initrd_image() section mismatch 2019-06-29 16:43:45 +08:00
ipc treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
kernel ptrace: Fix ->ptracer_cred handling for PTRACE_TRACEME 2019-07-05 02:00:41 +09:00
lib XArray updates for 5.2-rc6 2019-06-29 17:14:57 +08:00
LICENSES
mm mm/vmscan.c: prevent useless kswapd loops 2019-07-05 11:12:07 +09:00
net Bluetooth: Fix faulty expression for minimum encryption key size check 2019-07-03 16:09:09 +08:00
samples samples: make pidfd-metadata fail gracefully on older kernels 2019-06-24 15:55:50 +02:00
scripts treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 505 2019-06-19 17:11:22 +02:00
security SPDX update for 5.2-rc6 2019-06-21 09:58:42 -07:00
sound sound fixes for 5.2 2019-07-05 02:03:50 +09:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-06-29 19:39:17 +08:00
usr
virt SPDX update for 5.2-rc6 2019-06-21 09:58:42 -07:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap MAINTAINERS: Update my email address 2019-06-18 14:37:27 +01:00
COPYING
CREDITS MAINTAINERS: Farewell Martin Schwidefsky 2019-05-31 10:14:11 +02:00
Kbuild
Kconfig
MAINTAINERS MAINTAINERS: add CLANG/LLVM BUILD SUPPORT info 2019-06-29 16:43:45 +08:00
Makefile Linux 5.2-rc7 2019-06-30 11:25:36 +08:00
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.