linux.git/drivers/base/cacheinfo.c, branch v7.2-rc1

sched/cache: Calculate the LLC size and store it in sched_domain

2026-05-18T19:33:15+00:00

Cache aware scheduling needs to know the LLC size that a process
can use, so as to avoid memory-intensive tasks from being
over-aggregated on a single LLC.

Introduce a preparation patch to add get_effective_llc_bytes() to
get the LLC size that a CPU can use. The function can be further
enhanced by subtracting the LLC cache ways reserved by resctrl
(CAT in Intel RDT, etc).

Suggested-by: Peter Zijlstra (Intel) 
Signed-off-by: Chen Yu 
Co-developed-by: Tim Chen 
Signed-off-by: Tim Chen 
Signed-off-by: Peter Zijlstra (Intel) 
Tested-by: Tingyin Duan 
Link: https://patch.msgid.link/37afee09ff608034da0ce149e72d33b6f4698edf.1778703694.git.tim.c.chen@linux.intel.com

Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses

2026-02-22T16:26:33+00:00

Conversion performed via this Coccinelle script:

  // SPDX-License-Identifier: GPL-2.0-only
  // Options: --include-headers-for-types --all-includes --include-headers --keep-comments
  virtual patch

  @gfp depends on patch && !(file in "tools") && !(file in "samples")@
  identifier ALLOC = {kmalloc_obj,kmalloc_objs,kmalloc_flex,
 		    kzalloc_obj,kzalloc_objs,kzalloc_flex,
		    kvmalloc_obj,kvmalloc_objs,kvmalloc_flex,
		    kvzalloc_obj,kvzalloc_objs,kvzalloc_flex};
  @@

  	ALLOC(...
  -		, GFP_KERNEL
  	)

  $ make coccicheck MODE=patch COCCI=gfp.cocci

Build and boot tested x86_64 with Fedora 42's GCC and Clang:

Linux version 6.19.0+ (user@host) (gcc (GCC) 15.2.1 20260123 (Red Hat 15.2.1-7), GNU ld version 2.44-12.fc42) #1 SMP PREEMPT_DYNAMIC 1970-01-01
Linux version 6.19.0+ (user@host) (clang version 20.1.8 (Fedora 20.1.8-4.fc42), LLD 20.1.8) #1 SMP PREEMPT_DYNAMIC 1970-01-01

Signed-off-by: Kees Cook 
Signed-off-by: Linus Torvalds

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook

cacheinfo: Add arch hook to compress CPU h/w id into 32 bits for cache-id

2025-07-16T13:04:27+00:00

Filesystems like resctrl use the cache-id exposed via sysfs to identify
groups of CPUs. The value is also used for PCIe cache steering tags. On
DT platforms cache-id is not something that is described in the
device-tree, but instead generated from the smallest CPU h/w id of the
CPUs associated with that cache.

CPU h/w ids may be larger than 32 bits.

Add a hook to allow architectures to compress the value from the devicetree
into 32 bits. Returning the same value is always safe as cache_of_set_id()
will stop if a value larger than 32 bits is seen.

For example, on arm64 the value is the MPIDR affinity register, which only
has 32 bits of affinity data, but spread accross the 64 bit field. An
arch-specific bit swizzle gives a 32 bit value.

Signed-off-by: James Morse 
Reviewed-by: Jonathan Cameron 
Reviewed-by: Gavin Shan 
Link: https://lore.kernel.org/r/20250711182743.30141-3-james.morse@arm.com
Signed-off-by: Greg Kroah-Hartman

cacheinfo: Set cache 'id' based on DT data

2025-07-16T13:04:16+00:00

Use the minimum CPU h/w id of the CPUs associated with the cache for the
cache 'id'. This will provide a stable id value for a given system. As
we need to check all possible CPUs, we can't use the shared_cpu_map
which is just online CPUs. As there's not a cache to CPUs mapping in DT,
we have to walk all CPU nodes and then walk cache levels.

The cache_id exposed to user-space has historically been 32 bits, and
is too late to change. This value is parsed into a u32 by user-space
libraries such as libvirt:
https://github.com/libvirt/libvirt/blob/master/src/util/virresctrl.c#L1588

Give up on assigning cache-id's if a CPU h/w id greater than 32 bits
is found.

match_cache_node() does not make use of the __free() cleanup helpers
because of_find_next_cache_node(prev) does not drop a reference to prev,
and its too easy to accidentally drop the reference on cpu, which belongs
to for_each_of_cpu_node().

Cc: "Rafael J. Wysocki" 
Signed-off-by: Rob Herring 
[ ben: converted to use the __free cleanup idiom ]
Signed-off-by: Ben Horgan 
[ morse: Add checks to give up if a value larger than 32 bits is seen. ]
Signed-off-by: James Morse 
Reviewed-by: Jonathan Cameron 
Reviewed-by: Gavin Shan 
Link: https://lore.kernel.org/r/20250711182743.30141-2-james.morse@arm.com
Signed-off-by: Greg Kroah-Hartman

cacheinfo: Allocate memory during CPU hotplug if not done from the primary CPU

2024-12-06T12:07:47+00:00

Commit

  5944ce092b97 ("arch_topology: Build cacheinfo from primary CPU")

adds functionality that architectures can use to optionally allocate and
build cacheinfo early during boot. Commit

  6539cffa9495 ("cacheinfo: Add arch specific early level initializer")

lets secondary CPUs correct (and reallocate memory) cacheinfo data if
needed.

If the early build functionality is not used and cacheinfo does not need
correction, memory for cacheinfo is never allocated. x86 does not use
the early build functionality. Consequently, during the cacheinfo CPU
hotplug callback, last_level_cache_is_valid() attempts to dereference
a NULL pointer:

  BUG: kernel NULL pointer dereference, address: 0000000000000100
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not present page
  PGD 0 P4D 0
  Oops: 0000 [#1] PREEPMT SMP NOPTI
  CPU: 0 PID 19 Comm: cpuhp/0 Not tainted 6.4.0-rc2 #1
  RIP: 0010: last_level_cache_is_valid+0x95/0xe0a

Allocate memory for cacheinfo during the cacheinfo CPU hotplug callback
if not done earlier.

Moreover, before determining the validity of the last-level cache info,
ensure that it has been allocated. Simply checking for non-zero
cache_leaves() is not sufficient, as some architectures (e.g., Intel
processors) have non-zero cache_leaves() before allocation.

Dereferencing NULL cacheinfo can occur in update_per_cpu_data_slice_size().
This function iterates over all online CPUs. However, a CPU may have come
online recently, but its cacheinfo may not have been allocated yet.

While here, remove an unnecessary indentation in allocate_cache_info().

  [ bp: Massage. ]

Fixes: 6539cffa9495 ("cacheinfo: Add arch specific early level initializer")
Signed-off-by: Ricardo Neri 
Signed-off-by: Borislav Petkov (AMD) 
Reviewed-by: Radu Rendec 
Reviewed-by: Nikolay Borisov 
Reviewed-by: Andreas Herrmann 
Reviewed-by: Sudeep Holla 
Cc: stable@vger.kernel.org # 6.3+
Link: https://lore.kernel.org/r/20241128002247.26726-2-ricardo.neri-calderon@linux.intel.com

cacheinfo: Use of_property_present() for non-boolean properties

2024-11-10T09:54:07+00:00

The use of of_property_read_bool() for non-boolean properties is
deprecated in favor of of_property_present() when testing for property
presence.

Signed-off-by: Rob Herring (Arm) 
Link: https://lore.kernel.org/r/20241104190342.270883-1-robh@kernel.org
Signed-off-by: Greg Kroah-Hartman

cacheinfo: Don't opencode per_cpu_cacheinfo()

2024-11-04T00:59:06+00:00

That file contains a local helper that returns ->info_list, just use it.
No functional changes.

Signed-off-by: Nikolay Borisov 
Link: https://lore.kernel.org/r/20241023051118.888065-1-nik.borisov@suse.com
Signed-off-by: Greg Kroah-Hartman

drivers: cacheinfo: use __free attribute instead of of_node_put()

2024-07-31T11:56:34+00:00

Introduce the __free attribute for scope-based resource management.
Resources allocated with __free are automatically released at the end of
the scope. This enhancement aims to mitigate memory management issues
associated with forgetting to release resources by utilizing __free
instead of of_node_put().

To introduce this feature, some modifications to the code structure were
necessary. The original pattern:
```
prev = np;
while(...) {
  [...]
  np = of_find_next_cache_node(np);
  of_node_put(prev);
  prev = np;
  [...]
}
```
has been updated to:
```
while(...) {
  [...]
  struct device_node __free(device_node) *prev = np;
  np =  of_find_next_cache_node(np)
  [...]
}
```
With this change, the previous node is automatically cleaned up at the end
of each iteration, allowing the elimination of all of_node_put() calls and
some goto statements.

Suggested-by: Julia Lawall 
Signed-off-by: Vincenzo Mezzela 
Link: https://lore.kernel.org/r/20240719151335.869145-1-vincenzo.mezzela@gmail.com
Signed-off-by: Greg Kroah-Hartman

mm and cache_info: remove unnecessary CPU cache info update

2024-02-22T18:24:41+00:00

For each CPU hotplug event, we will update per-CPU data slice size and
corresponding PCP configuration for every online CPU to make the
implementation simple.  But, Kyle reported that this takes tens seconds
during boot on a machine with 34 zones and 3840 CPUs.

So, in this patch, for each CPU hotplug event, we only update per-CPU data
slice size and corresponding PCP configuration for the CPUs that share
caches with the hotplugged CPU.  With the patch, the system boot time
reduces 67 seconds on the machine.

Link: https://lkml.kernel.org/r/20240126081944.414520-1-ying.huang@intel.com
Fixes: 362d37a106dd ("mm, pcp: reduce lock contention for draining high-order pages")
Signed-off-by: "Huang, Ying" 
Originally-by: Kyle Meyer 
Reported-and-tested-by: Kyle Meyer 
Cc: Sudeep Holla 
Cc: Mel Gorman 
Signed-off-by: Andrew Morton