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Peter Xu 7e3ce3f8d2 mm: fix a few rare cases of using swapin error pte marker 
This patch should harden commit 15520a3f04 ("mm: use pte markers for
swap errors") on using pte markers for swapin errors on a few corner
cases.

1. Propagate swapin errors across fork()s: if there're swapin errors in
   the parent mm, after fork()s the child should sigbus too when an error
   page is accessed.

2. Fix a rare condition race in pte_marker_clear() where a uffd-wp pte
   marker can be quickly switched to a swapin error.

3. Explicitly ignore swapin error pte markers in change_protection().

I mostly don't worry on (2) or (3) at all, but we should still have them. 
Case (1) is special because it can potentially cause silent data corrupt
on child when parent has swapin error triggered with swapoff, but since
swapin error is rare itself already it's probably not easy to trigger
either.

Currently there is a priority difference between the uffd-wp bit and the
swapin error entry, in which the swapin error always has higher priority
(e.g.  we don't need to wr-protect a swapin error pte marker).

If there will be a 3rd bit introduced, we'll probably need to consider a
more involved approach so we may need to start operate on the bits.  Let's
leave that for later.

This patch is tested with case (1) explicitly where we'll get corrupted
data before in the child if there's existing swapin error pte markers, and
after patch applied the child can be rightfully killed.

We don't need to copy stable for this one since 15520a3f04 just landed
as part of v6.2-rc1, only "Fixes" applied.

Link: https://lkml.kernel.org/r/20221214200453.1772655-3-peterx@redhat.com
Fixes: 15520a3f04 ("mm: use pte markers for swap errors")
Signed-off-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Pengfei Xu <pengfei.xu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-01-18 17:02:19 -08:00
arch - Make sure the poking PGD is pinned for Xen PV as it requires it this way 2023-01-15 07:17:44 -06:00
block block-6.2-2023-01-13 2023-01-13 17:41:19 -06:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto This update includes the following changes: 2022-12-14 12:31:09 -08:00
Documentation Sync with v6.2-rc4 2023-01-18 16:52:20 -08:00
drivers - Fix the EDAC device's confusion in the polling setting units 2023-01-15 07:12:58 -06:00
fs Sync with v6.2-rc4 2023-01-18 16:52:20 -08:00
include Sync with v6.2-rc4 2023-01-18 16:52:20 -08:00
init Sync with v6.2-rc4 2023-01-18 16:52:20 -08:00
io_uring io_uring: lock overflowing for IOPOLL 2023-01-13 07:32:46 -07:00
ipc Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
kernel modules-6.2-rc4 2023-01-14 08:17:27 -06:00
lib Sync with v6.2-rc4 2023-01-18 16:52:20 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: fix a few rare cases of using swapin error pte marker 2023-01-18 17:02:19 -08:00
net Including fixes from rxrpc. 2023-01-12 18:20:44 -06:00
rust rust: types: add Opaque type 2022-12-04 01:59:16 +01:00
samples Char/Misc driver changes for 6.2-rc1 2022-12-16 03:49:24 -08:00
scripts kernel hardening fixes for v6.2-rc4 2023-01-14 10:04:00 -06:00
security kernel hardening fixes for v6.2-rc1 2022-12-23 12:00:24 -08:00
sound sound fixes for 6.2-rc4 2023-01-13 08:20:29 -06:00
tools Sync with v6.2-rc4 2023-01-18 16:52:20 -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: Ensure lockdep knows about kvm->lock vs. vcpu->mutex ordering rule 2023-01-11 13:32:21 -05:00
.clang-format iommufd for 6.2 2022-12-14 09:15:43 -08:00
.cocciconfig
.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 .gitignore: ignore *.rpm 2022-12-30 17:22:14 +09:00
.mailmap Sync with v6.2-rc4 2023-01-18 16:52:20 -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: zram: zsmalloc: Add an additional co-maintainer 2022-12-15 16:37:49 -08:00
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 Sync with v6.2-rc4 2023-01-18 16:52:20 -08:00
Makefile Linux 6.2-rc4 2023-01-15 09:22:43 -06:00
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.