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Matthew Wilcox (Oracle) 9025ee1079 block: Remove special-casing of compound pages 
commit 1b151e2435 upstream.

The special casing was originally added in pre-git history; reproducing
the commit log here:

> commit a318a92567d77
> Author: Andrew Morton <akpm@osdl.org>
> Date:   Sun Sep 21 01:42:22 2003 -0700
>
>     [PATCH] Speed up direct-io hugetlbpage handling
>
>     This patch short-circuits all the direct-io page dirtying logic for
>     higher-order pages.  Without this, we pointlessly bounce BIOs up to
>     keventd all the time.

In the last twenty years, compound pages have become used for more than
just hugetlb.  Rewrite these functions to operate on folios instead
of pages and remove the special case for hugetlbfs; I don't think
it's needed any more (and if it is, we can put it back in as a call
to folio_test_hugetlb()).

This was found by inspection; as far as I can tell, this bug can lead
to pages used as the destination of a direct I/O read not being marked
as dirty.  If those pages are then reclaimed by the MM without being
dirtied for some other reason, they won't be written out.  Then when
they're faulted back in, they will not contain the data they should.
It'll take a pretty unusual setup to produce this problem with several
races all going the wrong way.

This problem predates the folio work; it could for example have been
triggered by mmaping a THP in tmpfs and using that as the target of an
O_DIRECT read.

Fixes: 800d8c63b2 ("shmem: add huge pages support")
Cc:  <stable@vger.kernel.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2024-01-25 15:27:52 -08:00
arch LoongArch: BPF: Prevent out-of-bounds memory access 2024-01-25 15:27:50 -08:00
block block: Remove special-casing of compound pages 2024-01-25 15:27:52 -08:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: scomp - fix req->dst buffer overflow 2024-01-25 15:27:23 -08:00
Documentation dt-bindings: gpio: xilinx: Fix node address in gpio 2024-01-25 15:27:50 -08:00
drivers i2c: s3c24xx: fix transferring more than one message in polling mode 2024-01-25 15:27:52 -08:00
fs ksmbd: only v2 leases handle the directory 2024-01-25 15:27:41 -08:00
include netfilter: bridge: replace physindev with physinif in nf_bridge_info 2024-01-25 15:27:51 -08:00
init rootfs: Fix support for rootfstype= when root= is given 2024-01-25 15:27:43 -08:00
io_uring io_uring/rw: ensure io->bytes_done is always initialized 2024-01-25 15:27:41 -08:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel kdb: Fix a potential buffer overflow in kdb_local() 2024-01-25 15:27:51 -08:00
lib kunit: debugfs: Fix unchecked dereference in debugfs_print_results() 2024-01-25 15:27:21 -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 mm: fix unmap_mapping_range high bits shift bug 2024-01-10 17:10:35 +01:00
net ipv6: mcast: fix data-race in ipv6_mc_down / mld_ifc_work 2024-01-25 15:27:51 -08:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples fprobe: Pass entry_data to handlers 2023-10-25 12:03:12 +02:00
scripts powerpc: remove checks for binutils older than 2.25 2024-01-25 15:27:18 -08:00
security apparmor: avoid crash when parsed profile name is empty 2024-01-25 15:27:48 -08:00
sound ASoC: mediatek: sof-common: Add NULL check for normal_link string 2024-01-25 15:27:48 -08:00
tools selftests: mlxsw: qos_pfc: Adjust the test to support 8 lanes 2024-01-25 15:27:51 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:42:46 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.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 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -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 MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
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 genirq/affinity: Move group_cpus_evenly() into lib/ 2024-01-10 17:10:33 +01:00
Makefile Linux 6.1.74 2024-01-20 11:50:11 +01:00
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.