mainlining shenanigans
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David Hildenbrand 363106c4ce mm/khugepaged: remove reuse_swap_page() usage
reuse_swap_page() currently indicates if we can write to an anon page
without COW.  A COW is required if the page is shared by multiple
processes (either already mapped or via swap entries) or if there is
concurrent writeback that cannot tolerate concurrent page modifications.

However, in the context of khugepaged we're not actually going to write to
a read-only mapped page, we'll copy the page content to our newly
allocated THP and map that THP writable.  All we have to make sure is that
the read-only mapped page we're about to copy won't get reused by another
process sharing the page, otherwise, page content would get modified.  But
that is already guaranteed via multiple mechanisms (e.g., holding a
reference, holding the page lock, removing the rmap after copying the
page).

The swapcache handling was introduced in commit 10359213d0 ("mm:
incorporate read-only pages into transparent huge pages") and it sounds
like it merely wanted to mimic what do_swap_page() would do when trying to
map a page obtained via the swapcache writable.

As that logic is unnecessary, let's just remove it, removing the last user
of reuse_swap_page().

Link: https://lkml.kernel.org/r/20220131162940.210846-7-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Liang Zhang <zhangliang5@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-03-24 19:06:51 -07:00
arch arm64: select KASAN_VMALLOC for SW/HW_TAGS modes 2022-03-24 19:06:48 -07:00
block Filesystem folio changes for 5.18 2022-03-22 18:26:56 -07:00
certs KEYS: Introduce link restriction for machine keys 2022-03-08 13:55:52 +02:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2022-03-21 16:02:36 -07:00
Documentation kasan: documentation updates 2022-03-24 19:06:48 -07:00
drivers Networking changes for 5.18. 2022-03-24 13:13:26 -07:00
fs Merge branch 'akpm' (patches from Andrew) 2022-03-24 14:14:07 -07:00
include mm/khugepaged: remove reuse_swap_page() usage 2022-03-24 19:06:51 -07:00
init Merge branch 'akpm' (patches from Andrew) 2022-03-24 14:14:07 -07:00
ipc fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
kernel kasan, vmalloc: only tag normal vmalloc allocations 2022-03-24 19:06:48 -07:00
lib kasan: update function name in comments 2022-03-24 19:06:48 -07:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm/khugepaged: remove reuse_swap_page() usage 2022-03-24 19:06:51 -07:00
net Networking changes for 5.18. 2022-03-24 13:13:26 -07:00
samples Networking changes for 5.18. 2022-03-24 13:13:26 -07:00
scripts Merge branch 'akpm' (patches from Andrew) 2022-03-24 14:14:07 -07:00
security Networking changes for 5.18. 2022-03-24 13:13:26 -07:00
sound flexible-array transformations for 5.18-rc1 2022-03-24 11:39:32 -07:00
tools userfaultfd/selftests: enable hugetlb remap and remove event testing 2022-03-24 19:06:50 -07:00
usr reiserfs_xattr.h: add linux/reiserfs_xattr.h to UAPI compile-test coverage 2022-02-17 09:09:38 +01:00
virt KVM: compat: riscv: Prevent KVM_COMPAT from being selected 2022-03-11 19:02:15 +05:30
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig
.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 MAINTAINERS: Update Jisheng's email address 2022-03-08 17:30:32 +01:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
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 Networking changes for 5.18. 2022-03-24 13:13:26 -07:00
Makefile Linux 5.17 2022-03-20 13:14:17 -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.