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Hugh Dickins 47d4f3eeef mm/thp: shrink_page_list() avoid splitting VM_LOCKED THP
4.8 commit 7751b2da6b ("vmscan: split file huge pages before paging
them out") inserted a split_huge_page_to_list() into shrink_page_list()
without considering the mlock case: no problem if the page has already
been marked as Mlocked (the !page_evictable check much higher up will
have skipped all this), but it has always been the case that races or
omissions in setting Mlocked can rely on page reclaim to detect this
and correct it before actually reclaiming - and that remains so, but
what a shame if a hugepage is needlessly split before discovering it.

It is surprising that page_check_references() returns PAGEREF_RECLAIM
when VM_LOCKED, but there was a good reason for that: try_to_unmap_one()
is where the condition is detected and corrected; and until now it could
not be done in page_referenced_one(), because that does not always have
the page locked.  Now that mlock's requirement for page lock has gone,
copy try_to_unmap_one()'s mlock restoration into page_referenced_one(),
and let page_check_references() return PAGEREF_ACTIVATE in this case.

But page_referenced_one() may find a pte mapping one part of a hugepage:
what hold should a pte mapped in a VM_LOCKED area exert over the entire
huge page?  That's debatable.  The approach taken here is to treat that
pte mapping in page_referenced_one() as if not VM_LOCKED, and if no
VM_LOCKED pmd mapping is found later in the walk, and lack of reference
permits, then PAGEREF_RECLAIM take it to attempted splitting as before.

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
2022-02-17 11:59:50 -05:00
Documentation Interrupt chip driver fixes: 2022-02-13 10:06:40 -08:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
arch ARM: 2022-02-15 11:07:59 -08:00
block block: bio-integrity: Advance seed correctly for larger interval sizes 2022-02-03 21:09:24 -07:00
certs certs: Fix build error when CONFIG_MODULE_SIG_KEY is empty 2022-01-23 00:08:44 +09:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2022-02-09 09:53:56 -08:00
drivers MMC core: 2022-02-16 12:09:22 -08:00
fs for-5.17-rc4-tag 2022-02-15 09:14:05 -08:00
include mm/munlock: maintain page->mlock_count while unevictable 2022-02-17 11:56:57 -05:00
init lib/stackdepot: allow optional init and stack_table allocation by kvmalloc() 2022-01-22 08:33:37 +02:00
ipc ipc/sem: do not sleep with a spin lock held 2022-02-04 09:25:05 -08:00
kernel mm/munlock: rmap call mlock_vma_page() munlock_vma_page() 2022-02-17 11:56:48 -05:00
lib lib/crypto: blake2s: avoid indirect calls to compression function for Clang CFI 2022-02-04 19:22:32 +01:00
mm mm/thp: shrink_page_list() avoid splitting VM_LOCKED THP 2022-02-17 11:59:50 -05:00
net Networking fixes for 5.17-rc4, including fixes from netfilter and can. 2022-02-10 16:01:22 -08:00
samples samples/seccomp: Adjust sample to also provide kill option 2022-02-10 19:09:12 -08:00
scripts kconfig: fix failing to generate auto.conf 2022-02-12 23:24:19 +09:00
security integrity-v5-17-fix 2022-02-07 09:55:14 -08:00
sound ASoC: Fixes for v5.17 2022-02-01 16:52:54 +01:00
tools ARM: 2022-02-15 11:07:59 -08:00
usr kbuild: remove include/linux/cyclades.h from header file check 2022-01-27 08:51:08 +01:00
virt Two larger x86 series: 2022-01-28 19:00:26 +02:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.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: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update Christian Brauner's email address 2022-02-01 11:21:31 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Removing Ohad from remoteproc/rpmsg maintenance 2021-12-08 10:09:40 -07:00
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 s390 updates for 5.17-rc4 2022-02-12 09:12:44 -08:00
Makefile Linux 5.17-rc4 2022-02-13 12:13:30 -08:00
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.