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SeongJae Park d44b509ba8 mm/damon: implement a function for max nr_accesses safe calculation
commit 35f5d94187 upstream.

Patch series "avoid divide-by-zero due to max_nr_accesses overflow".

The maximum nr_accesses of given DAMON context can be calculated by
dividing the aggregation interval by the sampling interval.  Some logics
in DAMON uses the maximum nr_accesses as a divisor.  Hence, the value
shouldn't be zero.  Such case is avoided since DAMON avoids setting the
agregation interval as samller than the sampling interval.  However, since
nr_accesses is unsigned int while the intervals are unsigned long, the
maximum nr_accesses could be zero while casting.

Avoid the divide-by-zero by implementing a function that handles the
corner case (first patch), and replaces the vulnerable direct max
nr_accesses calculations (remaining patches).

Note that the patches for the replacements are divided for broken commits,
to make backporting on required tres easier.  Especially, the last patch
is for a patch that not yet merged into the mainline but in mm tree.


This patch (of 4):

The maximum nr_accesses of given DAMON context can be calculated by
dividing the aggregation interval by the sampling interval.  Some logics
in DAMON uses the maximum nr_accesses as a divisor.  Hence, the value
shouldn't be zero.  Such case is avoided since DAMON avoids setting the
agregation interval as samller than the sampling interval.  However, since
nr_accesses is unsigned int while the intervals are unsigned long, the
maximum nr_accesses could be zero while casting.  Implement a function
that handles the corner case.

Note that this commit is not fixing the real issue since this is only
introducing the safe function that will replaces the problematic
divisions.  The replacements will be made by followup commits, to make
backporting on stable series easier.

Link: https://lkml.kernel.org/r/20231019194924.100347-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20231019194924.100347-2-sj@kernel.org
Fixes: 198f0f4c58 ("mm/damon/vaddr,paddr: support pageout prioritization")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: Jakub Acs <acsjakub@amazon.de>
Cc: <stable@vger.kernel.org>	[5.16+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-11-28 17:15:01 +00:00
arch KVM: x86: Fix lapic timer interrupt lost after loading a snapshot. 2023-11-28 17:15:00 +00:00
block blk-mq: make sure active queue usage is held for bio_integrity_prep() 2023-11-28 17:14:55 +00:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto crypto: pcrypt - Fix hungtask for PADATA_RESET 2023-11-28 17:14:46 +00:00
Documentation net/mlx5e: Add recovery flow for tx devlink health reporter for unhealthy PTP SQ 2023-11-28 17:14:57 +00:00
drivers dm crypt: account large pages in cc->n_allocated_pages 2023-11-28 17:15:01 +00:00
fs watchdog: move softlockup_panic back to early_param 2023-11-28 17:15:01 +00:00
include mm/damon: implement a function for max nr_accesses safe calculation 2023-11-28 17:15:01 +00:00
init proc: sysctl: prevent aliased sysctls from getting passed to init 2023-11-28 17:15:00 +00:00
io_uring io_uring/fdinfo: remove need for sqpoll lock for thread/pid retrieval 2023-11-28 17:14:56 +00:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel watchdog: move softlockup_panic back to early_param 2023-11-28 17:15:01 +00:00
lib lib/generic-radix-tree.c: Don't overflow in peek() 2023-11-28 17:14:40 +00:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/damon/ops-common: avoid divide-by-zero during region hotness calculation 2023-11-28 17:15:01 +00:00
net net: sched: do not offload flows with a helper in act_ct 2023-11-28 17:14:57 +00:00
rust rust: types: make Opaque be !Unpin 2023-11-08 14:09:04 +01:00
samples samples/bpf: syscall_tp_user: Fix array out-of-bound access 2023-11-28 17:14:52 +00:00
scripts randstruct: Fix gcc-plugin performance mode to stay in group 2023-11-28 17:14:58 +00:00
security apparmor: fix invalid reference on profile->disconnected 2023-11-20 11:57:12 +01:00
sound ALSA: hda/realtek: Add quirk for ASUS UX7602ZM 2023-11-28 17:14:52 +00:00
tools perf intel-pt: Fix async branch flags 2023-11-28 17:14:58 +00:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:53:29 +02:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.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: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Revert ".gitignore: ignore *.cover and *.mbx" 2023-07-04 15:05:12 -07:00
.mailmap mailmap: add entries for Simon Horman 2023-08-16 09:53:10 +01:00
.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 - Address -Wmissing-prototype warnings 2023-06-26 16:43:54 -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 sound fixes for 6.5 2023-08-25 08:48:14 -07:00
Makefile Linux 6.5.12 2023-11-20 11:57:26 +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.