The static code analysis tool "Coverity Scan" pointed the following
implementation details out for further development considerations:
CID 1309755: Unused value
In sw842_compress: A value assigned to a variable is never used. (CWE-563)
returned_value: Assigning value from add_repeat_template(p, repeat_count)
to ret here, but that stored value is overwritten before it can be used.
Conclusion:
Add error handling for the return value from an add_repeat_template()
call.
Fixes: 2da572c959 ("lib: add software 842 compression/decompression")
Signed-off-by: Tanya Agarwal <tanyaagarwal25699@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Following the standardization on crc32c() as the lib entry point for the
Castagnoli CRC32 instead of the previous mix of crc32c(), crc32c_le(),
and __crc32c_le(), make the same change to the underlying base and arch
functions that implement it.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250208024911.14936-7-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Drop the use of __pure and __attribute_const__ from the CRC32 library
functions that had them. Both of these are unusual optimizations that
don't help properly written code. They seem more likely to cause
problems than have any real benefit.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250208024911.14936-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Add support for architecture-optimized implementations of the CRC64
library functions, following the approach taken for the CRC32 and
CRC-T10DIF library functions.
Also take the opportunity to tweak the function prototypes:
- Use 'const void *' for the lib entry points (since this is easier for
users) but 'const u8 *' for the underlying arch and generic functions
(since this is easier for the implementations of these functions).
- Don't bother with __pure. It's an unusual optimization that doesn't
help properly written code. It's a weird quirk we can do without.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Acked-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20250130035130.180676-6-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
This CRC64 variant comes from the NVME NVM Command Set Specification
(https://nvmexpress.org/wp-content/uploads/NVM-Express-NVM-Command-Set-Specification-1.0e-2024.07.29-Ratified.pdf).
The "Rocksoft Model CRC Algorithm", published in 1993 and available at
https://www.zlib.net/crc_v3.txt, is a generalized CRC algorithm that can
calculate any variant of CRC, given a list of parameters such as
polynomial, bit order, etc. It is not a CRC variant.
The NVME NVM Command Set Specification has a table that gives the
"Rocksoft Model Parameters" for the CRC variant it uses. When support
for this CRC variant was added to Linux, this table seems to have been
misinterpreted as naming the CRC variant the "Rocksoft" CRC. In fact,
the table names the CRC variant as the "NVM Express 64b CRC".
Most implementations of this CRC variant outside Linux have been calling
it CRC64-NVME. Therefore, update Linux to match.
While at it, remove the superfluous "update" from the function name, so
crc64_rocksoft_update() is now just crc64_nvme(), matching most of the
other CRC library functions.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Acked-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20250130035130.180676-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Following what was done for the CRC32 and CRC-T10DIF library functions,
get rid of the pointless use of the crypto API and make
crc64_rocksoft_update() call into the library directly. This is faster
and simpler.
Remove crc64_rocksoft() (the version of the function that did not take a
'crc' argument) since it is unused.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: "Martin K. Petersen" <martin.petersen@oracle.com>
Acked-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20250130035130.180676-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Pull hardening fixes from Kees Cook:
"Address a KUnit stack initialization regression that got tickled on
m68k, and solve a Clang(v14 and earlier) bug found by 0day:
- Fix stackinit KUnit regression on m68k
- Use ARRAY_SIZE() for memtostr*()/strtomem*()"
* tag 'hardening-v6.14-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
string.h: Use ARRAY_SIZE() for memtostr*()/strtomem*()
compiler.h: Introduce __must_be_byte_array()
compiler.h: Move C string helpers into C-only kernel section
stackinit: Fix comment for test_small_end
stackinit: Keep selftest union size small on m68k
Pull misc fixes from Andrew Morton:
"21 hotfixes. 8 are cc:stable and the remainder address post-6.13
issues. 13 are for MM and 8 are for non-MM.
All are singletons, please see the changelogs for details"
* tag 'mm-hotfixes-stable-2025-02-01-03-56' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (21 commits)
MAINTAINERS: include linux-mm for xarray maintenance
revert "xarray: port tests to kunit"
MAINTAINERS: add lib/test_xarray.c
mailmap, MAINTAINERS, docs: update Carlos's email address
mm/hugetlb: fix hugepage allocation for interleaved memory nodes
mm: gup: fix infinite loop within __get_longterm_locked
mm, swap: fix reclaim offset calculation error during allocation
.mailmap: update email address for Christopher Obbard
kfence: skip __GFP_THISNODE allocations on NUMA systems
nilfs2: fix possible int overflows in nilfs_fiemap()
mm: compaction: use the proper flag to determine watermarks
kernel: be more careful about dup_mmap() failures and uprobe registering
mm/fake-numa: handle cases with no SRAT info
mm: kmemleak: fix upper boundary check for physical address objects
mailmap: add an entry for Hamza Mahfooz
MAINTAINERS: mailmap: update Yosry Ahmed's email address
scripts/gdb: fix aarch64 userspace detection in get_current_task
mm/vmscan: accumulate nr_demoted for accurate demotion statistics
ocfs2: fix incorrect CPU endianness conversion causing mount failure
mm/zsmalloc: add __maybe_unused attribute for is_first_zpdesc()
...
Pull hardening fixes from Kees Cook:
"This is a fix for the soon to be released GCC 15 which has regressed
its initialization of unions when performing explicit initialization
(i.e. a general problem, not specifically a hardening problem; we're
just carrying the fix).
Details in the final patch, Acked by Masahiro, with updated selftests
to validate the fix"
* tag 'hardening-v6.14-rc1-fix1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
kbuild: Use -fzero-init-padding-bits=all
stackinit: Add union initialization to selftests
stackinit: Add old-style zero-init syntax to struct tests
The stack initialization selftests were checking scalars, strings,
and structs, but not unions. Add union tests (which are mostly identical
setup to structs). This catches the recent union initialization behavioral
changes seen in GCC 15. Before GCC 15, this new test passes:
ok 18 test_small_start_old_zero
With GCC 15, it fails:
not ok 18 test_small_start_old_zero
Specifically, a union with a larger member where a smaller member is
initialized with the older "= { 0 }" syntax:
union test_small_start {
char one:1;
char two;
short three;
unsigned long four;
struct big_struct {
unsigned long array[8];
} big;
};
This is a regression in compiler behavior that Linux has depended on.
GCC does not seem likely to fix it, instead suggesting that affected
projects start using -fzero-init-padding-bits=unions:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118403
Link: https://lore.kernel.org/r/20250127191031.245214-2-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
Pull CRC cleanups from Eric Biggers:
"Simplify the kconfig options for controlling which CRC implementations
are built into the kernel, as was requested by Linus.
This means making the option to disable the arch code visible only
when CONFIG_EXPERT=y, and standardizing on a single generic
implementation of CRC32"
* tag 'crc-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux:
lib/crc32: remove other generic implementations
lib/crc: simplify the kconfig options for CRC implementations
Pull sysctl table constification from Joel Granados:
"All ctl_table declared outside of functions and that remain unmodified
after initialization are const qualified.
This prevents unintended modifications to proc_handler function
pointers by placing them in the .rodata section.
This is a continuation of the tree-wide effort started a few releases
ago with the constification of the ctl_table struct arguments in the
sysctl API done in 78eb4ea25c ("sysctl: treewide: constify the
ctl_table argument of proc_handlers")"
* tag 'constfy-sysctl-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl:
treewide: const qualify ctl_tables where applicable
Make the following simplifications to the kconfig options for choosing
CRC implementations for CRC32 and CRC_T10DIF:
1. Make the option to disable the arch-optimized code be visible only
when CONFIG_EXPERT=y.
2. Make a single option control the inclusion of the arch-optimized code
for all enabled CRC variants.
3. Make CRC32_SARWATE (a.k.a. slice-by-1 or byte-by-byte) be the only
generic CRC32 implementation.
The result is there is now just one option, CRC_OPTIMIZATIONS, which is
default y and can be disabled only when CONFIG_EXPERT=y.
Rationale:
1. Enabling the arch-optimized code is nearly always the right choice.
However, people trying to build the tiniest kernel possible would
find some use in disabling it. Anything we add to CRC32 is de facto
unconditional, given that CRC32 gets selected by something in nearly
all kernels. And unfortunately enabling the arch CRC code does not
eliminate the need to build the generic CRC code into the kernel too,
due to CPU feature dependencies. The size of the arch CRC code will
also increase slightly over time as more CRC variants get added and
more implementations targeting different instruction set extensions
get added. Thus, it seems worthwhile to still provide an option to
disable it, but it should be considered an expert-level tweak.
2. Considering the use case described in (1), there doesn't seem to be
sufficient value in making the arch-optimized CRC code be
independently configurable for different CRC variants. Note also
that multiple variants were already grouped together, e.g.
CONFIG_CRC32 actually enables three different variants of CRC32.
3. The bit-by-bit implementation is uselessly slow, whereas slice-by-n
for n=4 and n=8 use tables that are inconveniently large: 4096 bytes
and 8192 bytes respectively, compared to 1024 bytes for n=1. Higher
n gives higher instruction-level parallelism, so higher n easily wins
on traditional microbenchmarks on most CPUs. However, the larger
tables, which are accessed randomly, can be harmful in real-world
situations where the dcache may be cold or useful data may need be
evicted from the dcache. Meanwhile, today most architectures have
much faster CRC32 implementations using dedicated CRC32 instructions
or carryless multiplication instructions anyway, which make the
generic code obsolete in most cases especially on long messages.
Another reason for going with n=1 is that this is already what is
used by all the other CRC variants in the kernel. CRC32 was unique
in having support for larger tables. But as per the above this can
be considered an outdated optimization.
The standardization on slice-by-1 a.k.a. CRC32_SARWATE makes much of
the code in lib/crc32.c unused. A later patch will clean that up.
Link: https://lore.kernel.org/r/20250123212904.118683-2-ebiggers@kernel.org
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Kernel test robot reported an "imbalanced put" in the rcuref_put() slow
path, which turned out to be a false positive. Consider the following race:
ref = 0 (via rcuref_init(ref, 1))
T1 T2
rcuref_put(ref)
-> atomic_add_negative_release(-1, ref) # ref -> 0xffffffff
-> rcuref_put_slowpath(ref)
rcuref_get(ref)
-> atomic_add_negative_relaxed(1, &ref->refcnt)
-> return true; # ref -> 0
rcuref_put(ref)
-> atomic_add_negative_release(-1, ref) # ref -> 0xffffffff
-> rcuref_put_slowpath()
-> cnt = atomic_read(&ref->refcnt); # cnt -> 0xffffffff / RCUREF_NOREF
-> atomic_try_cmpxchg_release(&ref->refcnt, &cnt, RCUREF_DEAD)) # ref -> 0xe0000000 / RCUREF_DEAD
-> return true
-> cnt = atomic_read(&ref->refcnt); # cnt -> 0xe0000000 / RCUREF_DEAD
-> if (cnt > RCUREF_RELEASED) # 0xe0000000 > 0xc0000000
-> WARN_ONCE(cnt >= RCUREF_RELEASED, "rcuref - imbalanced put()")
The problem is the additional read in the slow path (after it
decremented to RCUREF_NOREF) which can happen after the counter has been
marked RCUREF_DEAD.
Prevent this by reusing the return value of the decrement. Now every "final"
put uses RCUREF_NOREF in the slow path and attempts the final cmpxchg() to
RCUREF_DEAD.
[ bigeasy: Add changelog ]
Fixes: ee1ee6db07 ("atomics: Provide rcuref - scalable reference counting")
Reported-by: kernel test robot <oliver.sang@intel.com>
Debugged-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: stable@vger.kernel.org
Closes: https://lore.kernel.org/oe-lkp/202412311453.9d7636a2-lkp@intel.com
Pull driver core and debugfs updates from Greg KH:
"Here is the big set of driver core and debugfs updates for 6.14-rc1.
Included in here is a bunch of driver core, PCI, OF, and platform rust
bindings (all acked by the different subsystem maintainers), hence the
merge conflict with the rust tree, and some driver core api updates to
mark things as const, which will also require some fixups due to new
stuff coming in through other trees in this merge window.
There are also a bunch of debugfs updates from Al, and there is at
least one user that does have a regression with these, but Al is
working on tracking down the fix for it. In my use (and everyone
else's linux-next use), it does not seem like a big issue at the
moment.
Here's a short list of the things in here:
- driver core rust bindings for PCI, platform, OF, and some i/o
functions.
We are almost at the "write a real driver in rust" stage now,
depending on what you want to do.
- misc device rust bindings and a sample driver to show how to use
them
- debugfs cleanups in the fs as well as the users of the fs api for
places where drivers got it wrong or were unnecessarily doing
things in complex ways.
- driver core const work, making more of the api take const * for
different parameters to make the rust bindings easier overall.
- other small fixes and updates
All of these have been in linux-next with all of the aforementioned
merge conflicts, and the one debugfs issue, which looks to be resolved
"soon""
* tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (95 commits)
rust: device: Use as_char_ptr() to avoid explicit cast
rust: device: Replace CString with CStr in property_present()
devcoredump: Constify 'struct bin_attribute'
devcoredump: Define 'struct bin_attribute' through macro
rust: device: Add property_present()
saner replacement for debugfs_rename()
orangefs-debugfs: don't mess with ->d_name
octeontx2: don't mess with ->d_parent or ->d_parent->d_name
arm_scmi: don't mess with ->d_parent->d_name
slub: don't mess with ->d_name
sof-client-ipc-flood-test: don't mess with ->d_name
qat: don't mess with ->d_name
xhci: don't mess with ->d_iname
mtu3: don't mess wiht ->d_iname
greybus/camera - stop messing with ->d_iname
mediatek: stop messing with ->d_iname
netdevsim: don't embed file_operations into your structs
b43legacy: make use of debugfs_get_aux()
b43: stop embedding struct file_operations into their objects
carl9170: stop embedding file_operations into their objects
...
Add the const qualifier to all the ctl_tables in the tree except for
watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls,
loadpin_sysctl_table and the ones calling register_net_sysctl (./net,
drivers/inifiniband dirs). These are special cases as they use a
registration function with a non-const qualified ctl_table argument or
modify the arrays before passing them on to the registration function.
Constifying ctl_table structs will prevent the modification of
proc_handler function pointers as the arrays would reside in .rodata.
This is made possible after commit 78eb4ea25c ("sysctl: treewide:
constify the ctl_table argument of proc_handlers") constified all the
proc_handlers.
Created this by running an spatch followed by a sed command:
Spatch:
virtual patch
@
depends on !(file in "net")
disable optional_qualifier
@
identifier table_name != {
watchdog_hardlockup_sysctl,
iwcm_ctl_table,
ucma_ctl_table,
memory_allocation_profiling_sysctls,
loadpin_sysctl_table
};
@@
+ const
struct ctl_table table_name [] = { ... };
sed:
sed --in-place \
-e "s/struct ctl_table .table = &uts_kern/const struct ctl_table *table = \&uts_kern/" \
kernel/utsname_sysctl.c
Reviewed-by: Song Liu <song@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> # for kernel/trace/
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> # SCSI
Reviewed-by: Darrick J. Wong <djwong@kernel.org> # xfs
Acked-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Corey Minyard <cminyard@mvista.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Bill O'Donnell <bodonnel@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Acked-by: Anna Schumaker <anna.schumaker@oracle.com>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Pull Char/Misc/IIO driver updates from Greg KH:
"Here is the "big" set of char/misc/iio and other smaller driver
subsystem updates for 6.14-rc1. Loads of different things in here this
development cycle, highlights are:
- ntsync "driver" to handle Windows locking types enabling Wine to
work much better on many workloads (i.e. games). The driver
framework was in 6.13, but now it's enabled and fully working
properly. Should make many SteamOS users happy. Even comes with
tests!
- Large IIO driver updates and bugfixes
- FPGA driver updates
- Coresight driver updates
- MHI driver updates
- PPS driver updatesa
- const bin_attribute reworking for many drivers
- binder driver updates
- smaller driver updates and fixes
All of these have been in linux-next for a while with no reported
issues"
* tag 'char-misc-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (311 commits)
ntsync: Fix reference leaks in the remaining create ioctls.
spmi: hisi-spmi-controller: Drop duplicated OF node assignment in spmi_controller_probe()
spmi: Set fwnode for spmi devices
ntsync: fix a file reference leak in drivers/misc/ntsync.c
scripts/tags.sh: Don't tag usages of DECLARE_BITMAP
dt-bindings: interconnect: qcom,msm8998-bwmon: Add SM8750 CPU BWMONs
dt-bindings: interconnect: OSM L3: Document sm8650 OSM L3 compatible
dt-bindings: interconnect: qcom-bwmon: Document QCS615 bwmon compatibles
interconnect: sm8750: Add missing const to static qcom_icc_desc
memstick: core: fix kernel-doc notation
intel_th: core: fix kernel-doc warnings
binder: log transaction code on failure
iio: dac: ad3552r-hs: clear reset status flag
iio: dac: ad3552r-common: fix ad3541/2r ranges
iio: chemical: bme680: Fix uninitialized variable in __bme680_read_raw()
misc: fastrpc: Fix copy buffer page size
misc: fastrpc: Fix registered buffer page address
misc: fastrpc: Deregister device nodes properly in error scenarios
nvmem: core: improve range check for nvmem_cell_write()
nvmem: qcom-spmi-sdam: Set size in struct nvmem_config
...
Pull MM updates from Andrew Morton:
"The various patchsets are summarized below. Plus of course many
indivudual patches which are described in their changelogs.
- "Allocate and free frozen pages" from Matthew Wilcox reorganizes
the page allocator so we end up with the ability to allocate and
free zero-refcount pages. So that callers (ie, slab) can avoid a
refcount inc & dec
- "Support large folios for tmpfs" from Baolin Wang teaches tmpfs to
use large folios other than PMD-sized ones
- "Fix mm/rodata_test" from Petr Tesarik performs some maintenance
and fixes for this small built-in kernel selftest
- "mas_anode_descend() related cleanup" from Wei Yang tidies up part
of the mapletree code
- "mm: fix format issues and param types" from Keren Sun implements a
few minor code cleanups
- "simplify split calculation" from Wei Yang provides a few fixes and
a test for the mapletree code
- "mm/vma: make more mmap logic userland testable" from Lorenzo
Stoakes continues the work of moving vma-related code into the
(relatively) new mm/vma.c
- "mm/page_alloc: gfp flags cleanups for alloc_contig_*()" from David
Hildenbrand cleans up and rationalizes handling of gfp flags in the
page allocator
- "readahead: Reintroduce fix for improper RA window sizing" from Jan
Kara is a second attempt at fixing a readahead window sizing issue.
It should reduce the amount of unnecessary reading
- "synchronously scan and reclaim empty user PTE pages" from Qi Zheng
addresses an issue where "huge" amounts of pte pagetables are
accumulated:
https://lore.kernel.org/lkml/cover.1718267194.git.zhengqi.arch@bytedance.com/
Qi's series addresses this windup by synchronously freeing PTE
memory within the context of madvise(MADV_DONTNEED)
- "selftest/mm: Remove warnings found by adding compiler flags" from
Muhammad Usama Anjum fixes some build warnings in the selftests
code when optional compiler warnings are enabled
- "mm: don't use __GFP_HARDWALL when migrating remote pages" from
David Hildenbrand tightens the allocator's observance of
__GFP_HARDWALL
- "pkeys kselftests improvements" from Kevin Brodsky implements
various fixes and cleanups in the MM selftests code, mainly
pertaining to the pkeys tests
- "mm/damon: add sample modules" from SeongJae Park enhances DAMON to
estimate application working set size
- "memcg/hugetlb: Rework memcg hugetlb charging" from Joshua Hahn
provides some cleanups to memcg's hugetlb charging logic
- "mm/swap_cgroup: remove global swap cgroup lock" from Kairui Song
removes the global swap cgroup lock. A speedup of 10% for a
tmpfs-based kernel build was demonstrated
- "zram: split page type read/write handling" from Sergey Senozhatsky
has several fixes and cleaups for zram in the area of
zram_write_page(). A watchdog softlockup warning was eliminated
- "move pagetable_*_dtor() to __tlb_remove_table()" from Kevin
Brodsky cleans up the pagetable destructor implementations. A rare
use-after-free race is fixed
- "mm/debug: introduce and use VM_WARN_ON_VMG()" from Lorenzo Stoakes
simplifies and cleans up the debugging code in the VMA merging
logic
- "Account page tables at all levels" from Kevin Brodsky cleans up
and regularizes the pagetable ctor/dtor handling. This results in
improvements in accounting accuracy
- "mm/damon: replace most damon_callback usages in sysfs with new
core functions" from SeongJae Park cleans up and generalizes
DAMON's sysfs file interface logic
- "mm/damon: enable page level properties based monitoring" from
SeongJae Park increases the amount of information which is
presented in response to DAMOS actions
- "mm/damon: remove DAMON debugfs interface" from SeongJae Park
removes DAMON's long-deprecated debugfs interfaces. Thus the
migration to sysfs is completed
- "mm/hugetlb: Refactor hugetlb allocation resv accounting" from
Peter Xu cleans up and generalizes the hugetlb reservation
accounting
- "mm: alloc_pages_bulk: small API refactor" from Luiz Capitulino
removes a never-used feature of the alloc_pages_bulk() interface
- "mm/damon: extend DAMOS filters for inclusion" from SeongJae Park
extends DAMOS filters to support not only exclusion (rejecting),
but also inclusion (allowing) behavior
- "Add zpdesc memory descriptor for zswap.zpool" from Alex Shi
introduces a new memory descriptor for zswap.zpool that currently
overlaps with struct page for now. This is part of the effort to
reduce the size of struct page and to enable dynamic allocation of
memory descriptors
- "mm, swap: rework of swap allocator locks" from Kairui Song redoes
and simplifies the swap allocator locking. A speedup of 400% was
demonstrated for one workload. As was a 35% reduction for kernel
build time with swap-on-zram
- "mm: update mips to use do_mmap(), make mmap_region() internal"
from Lorenzo Stoakes reworks MIPS's use of mmap_region() so that
mmap_region() can be made MM-internal
- "mm/mglru: performance optimizations" from Yu Zhao fixes a few
MGLRU regressions and otherwise improves MGLRU performance
- "Docs/mm/damon: add tuning guide and misc updates" from SeongJae
Park updates DAMON documentation
- "Cleanup for memfd_create()" from Isaac Manjarres does that thing
- "mm: hugetlb+THP folio and migration cleanups" from David
Hildenbrand provides various cleanups in the areas of hugetlb
folios, THP folios and migration
- "Uncached buffered IO" from Jens Axboe implements the new
RWF_DONTCACHE flag which provides synchronous dropbehind for
pagecache reading and writing. To permite userspace to address
issues with massive buildup of useless pagecache when
reading/writing fast devices
- "selftests/mm: virtual_address_range: Reduce memory" from Thomas
Weißschuh fixes and optimizes some of the MM selftests"
* tag 'mm-stable-2025-01-26-14-59' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits)
mm/compaction: fix UBSAN shift-out-of-bounds warning
s390/mm: add missing ctor/dtor on page table upgrade
kasan: sw_tags: use str_on_off() helper in kasan_init_sw_tags()
tools: add VM_WARN_ON_VMG definition
mm/damon/core: use str_high_low() helper in damos_wmark_wait_us()
seqlock: add missing parameter documentation for raw_seqcount_try_begin()
mm/page-writeback: consolidate wb_thresh bumping logic into __wb_calc_thresh
mm/page_alloc: remove the incorrect and misleading comment
zram: remove zcomp_stream_put() from write_incompressible_page()
mm: separate move/undo parts from migrate_pages_batch()
mm/kfence: use str_write_read() helper in get_access_type()
selftests/mm/mkdirty: fix memory leak in test_uffdio_copy()
kasan: hw_tags: Use str_on_off() helper in kasan_init_hw_tags()
selftests/mm: virtual_address_range: avoid reading from VM_IO mappings
selftests/mm: vm_util: split up /proc/self/smaps parsing
selftests/mm: virtual_address_range: unmap chunks after validation
selftests/mm: virtual_address_range: mmap() without PROT_WRITE
selftests/memfd/memfd_test: fix possible NULL pointer dereference
mm: add FGP_DONTCACHE folio creation flag
mm: call filemap_fdatawrite_range_kick() after IOCB_DONTCACHE issue
...
Pull non-MM updates from Andrew Morton:
"Mainly individually changelogged singleton patches. The patch series
in this pull are:
- "lib min_heap: Improve min_heap safety, testing, and documentation"
from Kuan-Wei Chiu provides various tightenings to the min_heap
library code
- "xarray: extract __xa_cmpxchg_raw" from Tamir Duberstein preforms
some cleanup and Rust preparation in the xarray library code
- "Update reference to include/asm-<arch>" from Geert Uytterhoeven
fixes pathnames in some code comments
- "Converge on using secs_to_jiffies()" from Easwar Hariharan uses
the new secs_to_jiffies() in various places where that is
appropriate
- "ocfs2, dlmfs: convert to the new mount API" from Eric Sandeen
switches two filesystems to the new mount API
- "Convert ocfs2 to use folios" from Matthew Wilcox does that
- "Remove get_task_comm() and print task comm directly" from Yafang
Shao removes now-unneeded calls to get_task_comm() in various
places
- "squashfs: reduce memory usage and update docs" from Phillip
Lougher implements some memory savings in squashfs and performs
some maintainability work
- "lib: clarify comparison function requirements" from Kuan-Wei Chiu
tightens the sort code's behaviour and adds some maintenance work
- "nilfs2: protect busy buffer heads from being force-cleared" from
Ryusuke Konishi fixes an issues in nlifs when the fs is presented
with a corrupted image
- "nilfs2: fix kernel-doc comments for function return values" from
Ryusuke Konishi fixes some nilfs kerneldoc
- "nilfs2: fix issues with rename operations" from Ryusuke Konishi
addresses some nilfs BUG_ONs which syzbot was able to trigger
- "minmax.h: Cleanups and minor optimisations" from David Laight does
some maintenance work on the min/max library code
- "Fixes and cleanups to xarray" from Kemeng Shi does maintenance
work on the xarray library code"
* tag 'mm-nonmm-stable-2025-01-24-23-16' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (131 commits)
ocfs2: use str_yes_no() and str_no_yes() helper functions
include/linux/lz4.h: add some missing macros
Xarray: use xa_mark_t in xas_squash_marks() to keep code consistent
Xarray: remove repeat check in xas_squash_marks()
Xarray: distinguish large entries correctly in xas_split_alloc()
Xarray: move forward index correctly in xas_pause()
Xarray: do not return sibling entries from xas_find_marked()
ipc/util.c: complete the kernel-doc function descriptions
gcov: clang: use correct function param names
latencytop: use correct kernel-doc format for func params
minmax.h: remove some #defines that are only expanded once
minmax.h: simplify the variants of clamp()
minmax.h: move all the clamp() definitions after the min/max() ones
minmax.h: use BUILD_BUG_ON_MSG() for the lo < hi test in clamp()
minmax.h: reduce the #define expansion of min(), max() and clamp()
minmax.h: update some comments
minmax.h: add whitespace around operators and after commas
nilfs2: do not update mtime of renamed directory that is not moved
nilfs2: handle errors that nilfs_prepare_chunk() may return
CREDITS: fix spelling mistake
...
When memory allocation profiling is disabled there is no need to update
current->alloc_tag and these manipulations add unnecessary overhead. Fix
the overhead by skipping these extra updates.
I ran comprehensive testing on Pixel 6 on Big, Medium and Little cores:
Overhead before fixes Overhead after fixes
slab alloc page alloc slab alloc page alloc
Big 6.21% 5.32% 3.31% 4.93%
Medium 4.51% 5.05% 3.79% 4.39%
Little 7.62% 1.82% 6.68% 1.02%
This is an allocation microbenchmark doing allocations in a tight loop.
Not a really realistic scenario and useful only to make performance
comparisons.
Link: https://lkml.kernel.org/r/20241226211639.1357704-1-surenb@google.com
Fixes: b951aaff50 ("mm: enable page allocation tagging")
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Cc: David Wang <00107082@163.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zhenhua Huang <quic_zhenhuah@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
As of now during link list corruption it prints about cluprit address and
its wrong value, but sometime it is not enough to catch the actual issue
point.
If it prints allocation and free path of that corrupted node, it will be a
lot easier to find and fix the issues.
Adding the same information when data mismatch is found in link list
debug data:
[ 14.243055] slab kmalloc-32 start ffff0000cda19320 data offset 32 pointer offset 8 size 32 allocated at add_to_list+0x28/0xb0
[ 14.245259] __kmalloc_cache_noprof+0x1c4/0x358
[ 14.245572] add_to_list+0x28/0xb0
...
[ 14.248632] do_el0_svc_compat+0x1c/0x34
[ 14.249018] el0_svc_compat+0x2c/0x80
[ 14.249244] Free path:
[ 14.249410] kfree+0x24c/0x2f0
[ 14.249724] do_force_corruption+0xbc/0x100
...
[ 14.252266] el0_svc_common.constprop.0+0x40/0xe0
[ 14.252540] do_el0_svc_compat+0x1c/0x34
[ 14.252763] el0_svc_compat+0x2c/0x80
[ 14.253071] ------------[ cut here ]------------
[ 14.253303] list_del corruption. next->prev should be ffff0000cda192a8, but was 6b6b6b6b6b6b6b6b. (next=ffff0000cda19348)
[ 14.254255] WARNING: CPU: 3 PID: 84 at lib/list_debug.c:65 __list_del_entry_valid_or_report+0x158/0x164
Moved prototype of mem_dump_obj() to bug.h, as mm.h can not be included in
bug.h.
Link: https://lkml.kernel.org/r/20241230101043.53773-1-maninder1.s@samsung.com
Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
Acked-by: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Marco Elver <elver@google.com>
Cc: Rohit Thapliyal <r.thapliyal@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
We don't support large entries which expand two more level xa_node in
split. For case "xas->xa_shift + 2 * XA_CHUNK_SHIFT == order", we also
need two level of xa_node to expand. Distinguish entry as large entry in
case "xas->xa_shift + 2 * XA_CHUNK_SHIFT == order".
As max order of folio in pagecache (MAX_PAGECACHE_ORDER) is <=
(XA_CHUNK_SHIFT * 2 - 1), this change is more likely a cleanup...
Link: https://lkml.kernel.org/r/20241213122523.12764-4-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Mattew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
After xas_load(), xas->index could point to mid of found multi-index entry
and xas->index's bits under node->shift maybe non-zero. The afterward
xas_pause() will move forward xas->index with xa->node->shift with bits
under node->shift un-masked and thus skip some index unexpectedly.
Consider following case:
Assume XA_CHUNK_SHIFT is 4.
xa_store_range(xa, 16, 31, ...)
xa_store(xa, 32, ...)
XA_STATE(xas, xa, 17);
xas_for_each(&xas,...)
xas_load(&xas)
/* xas->index = 17, xas->xa_offset = 1, xas->xa_node->xa_shift = 4 */
xas_pause()
/* xas->index = 33, xas->xa_offset = 2, xas->xa_node->xa_shift = 4 */
As we can see, index of 32 is skipped unexpectedly.
Fix this by mask bit under node->xa_shift when move forward index in
xas_pause().
For now, this will not cause serious problems. Only minor problem like
cachestat return less number of page status could happen.
Link: https://lkml.kernel.org/r/20241213122523.12764-3-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Mattew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "Fixes and cleanups to xarray", v5.
This series contains some random fixes and cleanups to xarray. Patch 1-2
are fixes and patch 3-6 are cleanups. More details can be found in
respective patches.
This patch (of 5):
Similar to issue fixed in commit cbc0285433 ("XArray: Do not return
sibling entries from xa_load()"), we may return sibling entries from
xas_find_marked as following:
Thread A: Thread B:
xa_store_range(xa, entry, 6, 7, gfp);
xa_set_mark(xa, 6, mark)
XA_STATE(xas, xa, 6);
xas_find_marked(&xas, 7, mark);
offset = xas_find_chunk(xas, advance, mark);
[offset is 6 which points to a valid entry]
xa_store_range(xa, entry, 4, 7, gfp);
entry = xa_entry(xa, node, 6);
[entry is a sibling of 4]
if (!xa_is_node(entry))
return entry;
Skip sibling entry like xas_find() does to protect caller from seeing
sibling entry from xas_find_marked() or caller may use sibling entry
as a valid entry and crash the kernel.
Besides, load_race() test is modified to catch mentioned issue and modified
load_race() only passes after this fix is merged.
Here is an example how this bug could be triggerred in tmpfs which
enables large folio in mapping:
Let's take a look at involved racer:
1. How pages could be created and dirtied in shmem file.
write
ksys_write
vfs_write
new_sync_write
shmem_file_write_iter
generic_perform_write
shmem_write_begin
shmem_get_folio
shmem_allowable_huge_orders
shmem_alloc_and_add_folios
shmem_alloc_folio
__folio_set_locked
shmem_add_to_page_cache
XA_STATE_ORDER(..., index, order)
xax_store()
shmem_write_end
folio_mark_dirty()
2. How dirty pages could be deleted in shmem file.
ioctl
do_vfs_ioctl
file_ioctl
ioctl_preallocate
vfs_fallocate
shmem_fallocate
shmem_truncate_range
shmem_undo_range
truncate_inode_folio
filemap_remove_folio
page_cache_delete
xas_store(&xas, NULL);
3. How dirty pages could be lockless searched
sync_file_range
ksys_sync_file_range
__filemap_fdatawrite_range
filemap_fdatawrite_wbc
do_writepages
writeback_use_writepage
writeback_iter
writeback_get_folio
filemap_get_folios_tag
find_get_entry
folio = xas_find_marked()
folio_try_get(folio)
Kernel will crash as following:
1.Create 2.Search 3.Delete
/* write page 2,3 */
write
...
shmem_write_begin
XA_STATE_ORDER(xas, i_pages, index = 2, order = 1)
xa_store(&xas, folio)
shmem_write_end
folio_mark_dirty()
/* sync page 2 and page 3 */
sync_file_range
...
find_get_entry
folio = xas_find_marked()
/* offset will be 2 */
offset = xas_find_chunk()
/* delete page 2 and page 3 */
ioctl
...
xas_store(&xas, NULL);
/* write page 0-3 */
write
...
shmem_write_begin
XA_STATE_ORDER(xas, i_pages, index = 0, order = 2)
xa_store(&xas, folio)
shmem_write_end
folio_mark_dirty(folio)
/* get sibling entry from offset 2 */
entry = xa_entry(.., 2)
/* use sibling entry as folio and crash kernel */
folio_try_get(folio)
Link: https://lkml.kernel.org/r/20241213122523.12764-1-shikemeng@huaweicloud.com
Link: https://lkml.kernel.org/r/20241213122523.12764-2-shikemeng@huaweicloud.com
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Mattew Wilcox <willy@infradead.org> [English fixes]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
