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Zach O'Keefe fd71c8d3b0 mm/MADV_COLLAPSE: set EAGAIN on unexpected page refcount
commit ae63c898f4 upstream.

During collapse, in a few places we check to see if a given small page has
any unaccounted references.  If the refcount on the page doesn't match our
expectations, it must be there is an unknown user concurrently interested
in the page, and so it's not safe to move the contents elsewhere.
However, the unaccounted pins are likely an ephemeral state.

In this situation, MADV_COLLAPSE returns -EINVAL when it should return
-EAGAIN.  This could cause userspace to conclude that the syscall
failed, when it in fact could succeed by retrying.

Link: https://lkml.kernel.org/r/20230125015738.912924-1-zokeefe@google.com
Fixes: 7d8faaf155 ("mm/madvise: introduce MADV_COLLAPSE sync hugepage collapse")
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Reported-by: Hugh Dickins <hughd@google.com>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-02-22 12:59:49 +01:00
arch s390/decompressor: specify __decompress() buf len to avoid overflow 2023-02-22 12:59:43 +01:00
block block, bfq: fix uaf for bfqq in bic_set_bfqq() 2023-02-09 11:28:06 +01:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto use less confusing names for iov_iter direction initializers 2023-02-09 11:28:04 +01:00
Documentation Documentation/hw-vuln: Add documentation for Cross-Thread Return Predictions 2023-02-14 19:11:56 +01:00
drivers ata: libata-core: Disable READ LOG DMA EXT for Samsung MZ7LH 2023-02-22 12:59:49 +01:00
fs nilfs2: fix underflow in second superblock position calculations 2023-02-22 12:59:49 +01:00
include hugetlb: check for undefined shift on 32 bit architectures 2023-02-22 12:59:49 +01:00
init gcc: disable -Warray-bounds for gcc-11 too 2023-01-14 10:33:43 +01:00
io_uring use less confusing names for iov_iter direction initializers 2023-02-09 11:28:04 +01:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel sched/psi: Fix use-after-free in ep_remove_wait_queue() 2023-02-22 12:59:49 +01:00
lib maple_tree: fix mas_empty_area_rev() lower bound validation 2023-02-09 11:28:23 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm/MADV_COLLAPSE: set EAGAIN on unexpected page refcount 2023-02-22 12:59:49 +01:00
net net: sched: sch: Bounds check priority 2023-02-22 12:59:43 +01:00
rust rust: print: avoid evaluating arguments in pr_* macros in unsafe blocks 2023-02-06 08:06:34 +01:00
samples ftrace: Export ftrace_free_filter() to modules 2023-02-01 08:34:37 +01:00
scripts kbuild: modinst: Fix build error when CONFIG_MODULE_SIG_KEY is a PKCS#11 URI 2023-02-09 11:28:11 +01:00
security use less confusing names for iov_iter direction initializers 2023-02-09 11:28:04 +01:00
sound ALSA: hda/realtek: Enable mute/micmute LEDs and speaker support for HP Laptops 2023-02-22 12:59:48 +01:00
tools selftests: mptcp: userspace: fix v4-v6 test in v6.1 2023-02-22 12:59:45 +01:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: Fix potential deadlock on vfio group_lock 2023-02-01 08:34:36 +01:00
.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 panic: Expose "warn_count" to sysfs 2023-01-24 07:24:41 +01:00
Makefile Linux 6.1.12 2023-02-14 19:11:56 +01:00
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.