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Yang Shi 6d67b2a73b mm: khugepaged: skip huge page collapse for special files 
commit a4aeaa06d4 upstream.

The read-only THP for filesystems will collapse THP for files opened
readonly and mapped with VM_EXEC.  The intended usecase is to avoid TLB
misses for large text segments.  But it doesn't restrict the file types
so a THP could be collapsed for a non-regular file, for example, block
device, if it is opened readonly and mapped with EXEC permission.  This
may cause bugs, like [1] and [2].

This is definitely not the intended usecase, so just collapse THP for
regular files in order to close the attack surface.

[shy828301@gmail.com: fix vm_file check [3]]

Link: https://lore.kernel.org/lkml/CACkBjsYwLYLRmX8GpsDpMthagWOjWWrNxqY6ZLNQVr6yx+f5vA@mail.gmail.com/ [1]
Link: https://lore.kernel.org/linux-mm/000000000000c6a82505ce284e4c@google.com/ [2]
Link: https://lkml.kernel.org/r/CAHbLzkqTW9U3VvTu1Ki5v_cLRC9gHW+znBukg_ycergE0JWj-A@mail.gmail.com [3]
Link: https://lkml.kernel.org/r/20211027195221.3825-1-shy828301@gmail.com
Fixes: 99cb0dbd47 ("mm,thp: add read-only THP support for (non-shmem) FS")
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Yang Shi <shy828301@gmail.com>
Reported-by: Hao Sun <sunhao.th@gmail.com>
Reported-by: syzbot+aae069be1de40fb11825@syzkaller.appspotmail.com
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Andrea Righi <andrea.righi@canonical.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-06 14:10:09 +01:00
arch riscv: Fix asan-stack clang build 2021-11-02 19:48:25 +01:00
block block: decode QUEUE_FLAG_HCTX_ACTIVE in debugfs output 2021-10-27 09:56:46 +02:00
certs certs: Trigger creation of RSA module signing key if it's not an RSA key 2021-09-15 09:50:29 +02:00
crypto crypto: sm2 - fix a memory leak in sm2 2021-07-14 16:56:06 +02:00
Documentation dt-bindings: drm/bridge: ti-sn65dsi86: Fix reg value 2021-10-13 10:04:27 +02:00
drivers Revert "usb: core: hcd: Add support for deferring roothub registration" 2021-11-06 14:10:09 +01:00
fs Revert "io_uring: reinforce cancel on flush during exit" 2021-11-06 14:10:08 +01:00
include Revert "usb: core: hcd: Add support for deferring roothub registration" 2021-11-06 14:10:09 +01:00
init sched/core: Initialize the idle task with preemption disabled 2021-07-14 16:55:50 +02:00
ipc ipc/mqueue, msg, sem: avoid relying on a stack reference past its expiry 2021-05-26 12:06:54 +02:00
kernel bpf: Fix error usage of map_fd and fdget() in generic_map_update_batch() 2021-11-02 19:48:21 +01:00
lib treewide: Change list_sort to use const pointers 2021-09-30 10:11:04 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm: khugepaged: skip huge page collapse for special files 2021-11-06 14:10:09 +01:00
net sctp: add vtag check in sctp_sf_ootb 2021-11-02 19:48:24 +01:00
samples samples: bpf: Fix tracex7 error raised on the missing argument 2021-09-18 13:40:23 +02:00
scripts gcc-plugins/structleak: add makefile var for disabling structleak 2021-10-27 09:56:54 +02:00
security Smack: Fix wrong semantics in smk_access_entry() 2021-09-18 13:40:18 +02:00
sound ALSA: hda: avoid write to STATESTS if controller is in reset 2021-10-27 09:56:55 +02:00
tools perf script: Check session->header.env.arch before using it 2021-11-02 19:48:25 +01:00
usr Merge branch 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 13:29:39 -07:00
virt KVM: do not shrink halt_poll_ns below grow_start 2021-10-09 14:40:58 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.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 kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +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 f2fs: move ioctl interface definitions to separated file 2021-05-19 10:13:00 +02:00
Makefile Linux 5.10.77 2021-11-02 19:48:25 +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.