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The linux-next integration testing tree
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Kairui Song 0ec8bc9e88 mm, swap: fix allocation and scanning race with swapoff 
There are two flags used to synchronize allocation and scanning with
swapoff: SWP_WRITEOK and SWP_SCANNING.

SWP_WRITEOK: Swapoff will first unset this flag, at this point any further
swap allocation or scanning on this device should just abort so no more
new entries will be referencing this device.  Swapoff will then unuse all
existing swap entries.

SWP_SCANNING: This flag is set when device is being scanned.  Swapoff will
wait for all scanner to stop before the final release of the swap device
structures to avoid UAF.  Note this flag is the highest used bit of
si->flags so it could be added up arithmetically, if there are multiple
scanner.

commit 5f843a9a3a ("mm: swap: separate SSD allocation from
scan_swap_map_slots()") ignored SWP_SCANNING and SWP_WRITEOK flags while
separating cluster allocation path from the old allocation path.  Add the
flags back to fix swapoff race.  The race is hard to trigger as si->lock
prevents most parallel operations, but si->lock could be dropped for
reclaim or discard.  This issue is found during code review.

This commit fixes this problem.  For SWP_SCANNING, Just like before, set
the flag before scan and remove it afterwards.

For SWP_WRITEOK, there are several places where si->lock could be dropped,
it will be error-prone and make the code hard to follow if we try to cover
these places one by one.  So just do one check before the real allocation,
which is also very similar like before.  With new cluster allocator it may
waste a bit of time iterating the clusters but won't take long, and
swapoff is not performance sensitive.

Link: https://lkml.kernel.org/r/20241112083414.78174-1-ryncsn@gmail.com
Fixes: 5f843a9a3a ("mm: swap: separate SSD allocation from scan_swap_map_slots()")
Reported-by: "Huang, Ying" <ying.huang@intel.com>
Closes: https://lore.kernel.org/linux-mm/87a5es3f1f.fsf@yhuang6-desk2.ccr.corp.intel.com/
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-11-14 15:25:07 -08:00
arch mm: refactor arch_calc_vm_flag_bits() and arm64 MTE handling 2024-11-05 16:49:55 -08:00
block block-6.12-20241101 2024-11-01 13:41:55 -10:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto This push fixes the following issues: 2024-10-16 08:42:54 -07:00
Documentation mm: count zeromap read and set for swapout and swapin 2024-11-11 00:00:37 -08:00
drivers phy fixes for 6.12 2024-11-03 10:19:34 -10:00
fs ocfs2: fix UBSAN warning in ocfs2_verify_volume() 2024-11-11 17:20:23 -08:00
include mm: count zeromap read and set for swapout and swapin 2024-11-11 00:00:37 -08:00
init cfi: fix conditions for HAVE_CFI_ICALL_NORMALIZE_INTEGERS 2024-10-13 22:23:13 +02:00
io_uring io_uring/rw: fix missing NOWAIT check for O_DIRECT start write 2024-10-31 08:21:02 -06:00
ipc struct fd layout change (and conversion to accessor helpers) 2024-09-23 09:35:36 -07:00
kernel signal: restore the override_rlimit logic 2024-11-07 14:14:59 -08:00
lib objpool: fix to make percpu slot allocation more robust 2024-11-07 14:14:58 -08:00
LICENSES LICENSES: add 0BSD license text 2024-09-01 20:43:24 -07:00
mm mm, swap: fix allocation and scanning race with swapoff 2024-11-14 15:25:07 -08:00
net nfsd-6.12 fixes: 2024-11-02 09:27:11 -10:00
rust Driver core fix for 6.12-rc3 2024-10-13 09:10:52 -07:00
samples [tree-wide] finally take no_llseek out 2024-09-27 08:18:43 -07:00
scripts Kbuild fixes for v6.12 (2nd) 2024-11-03 08:29:02 -10:00
security ipe: fallback to platform keyring also if key in trusted keyring is rejected 2024-10-18 12:14:53 -07:00
sound ALSA: hda/realtek: Fix headset mic on TUXEDO Stellaris 16 Gen6 mb1 2024-10-30 14:46:59 +01:00
tools selftests: hugetlb_dio: fixup check for initial conditions to skip in the start 2024-11-12 10:14:00 -08:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt ARM64: 2024-10-21 11:22:04 -07:00
.clang-format clang-format: Update with v6.11-rc1's for_each macro list 2024-08-02 13:20:31 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Kbuild updates for v6.12 2024-09-24 13:02:06 -07:00
.mailmap mailmap: add entry for Thorsten Blum 2024-11-07 14:14:59 -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 CREDITS: sort alphabetically by name 2024-10-09 12:47:19 -07:00
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 Char/Misc/IIO driver fixes for 6.12-rc6 2024-11-03 08:45:03 -10:00
Makefile Linux 6.12-rc6 2024-11-03 14:05:52 -10:00
README README: Fix spelling 2024-03-18 03:36:32 -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 reStructuredText 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.