linux-stable.git/Documentation/kernel-hacking, branch master

Documentation: adopt new coding style of type-aware kmalloc-family

2026-05-03T14:54:21+00:00

Update the documentation to reflect new type-aware kmalloc-family as
suggested in commit 2932ba8d9c99 ("slab: Introduce kmalloc_obj()
and family")

ptr = kmalloc(sizeof(*ptr), gfp);
 -> ptr = kmalloc_obj(*ptr, gfp);
ptr = kmalloc(sizeof(struct some_obj_name), gfp);
 -> ptr = kmalloc_obj(*ptr, gfp);
ptr = kzalloc(sizeof(*ptr), gfp);
 -> ptr = kzalloc_obj(*ptr, gfp);
ptr = kmalloc_array(count, sizeof(*ptr), gfp);
 -> ptr = kmalloc_objs(*ptr, count, gfp);
ptr = kcalloc(count, sizeof(*ptr), gfp);
 -> ptr = kzalloc_objs(*ptr, count, gfp);

Signed-off-by: Manuel Ebner 
Acked-by: SeongJae Park 
Acked-by: Vlastimil Babka (SUSE) 
Signed-off-by: Jonathan Corbet 
Message-ID: <20260429071445.309733-2-manuelebner@mailbox.org>

Documentation: kernel-hacking: Remove :c:func: annotations

2026-01-06T22:15:15+00:00

Remove the useless :c:func: annotations.

Suggested-by: Jonathan Corbet 
Signed-off-by: Thorsten Blum 
Signed-off-by: Jonathan Corbet 
Message-ID: <20251222232506.2615-2-thorsten.blum@linux.dev>

Documentation: kernel-hacking: Convert internal links

2026-01-06T22:08:43+00:00

Convert internal cross-references in "Putting Your Stuff in the kernel"
section from inline code to internal links.

Signed-off-by: Bagas Sanjaya 
Signed-off-by: Jonathan Corbet 
Message-ID: <20251223035254.22894-4-bagasdotme@gmail.com>

Documentation: kernel-hacking: Do not italicize EXPORT_SYMBOL{,_GPL}() references

2026-01-06T22:08:43+00:00

Do not italicize EXPORT_SYMBOL() and EXPORT_SYMBOL_GPL() references in
EXPORT_SYMBOL_NS() and EXPORT_SYMBOL_NS_GPL() subsections.

Signed-off-by: Bagas Sanjaya 
Signed-off-by: Jonathan Corbet 
Message-ID: <20251223035254.22894-3-bagasdotme@gmail.com>

Documentation: kernel-hacking: Remove current macro annotation

2026-01-06T22:08:43+00:00

Remove unneeded :c:macro: annotation of current macro.

Signed-off-by: Bagas Sanjaya 
Signed-off-by: Jonathan Corbet 
Message-ID: <20251223035254.22894-2-bagasdotme@gmail.com>

Documentation: kernel-hacking: Remove comma

2025-12-22T21:40:24+00:00

The comma is wrong, remove it.

Signed-off-by: Thorsten Blum 
Acked-by: Randy Dunlap 
Signed-off-by: Jonathan Corbet 
Message-ID: <20251219171827.44015-2-thorsten.blum@linux.dev>

docs/licensing: Clarify wording about "GPL" and "Proprietary"

2024-11-22T17:44:25+00:00

There are currently some doubts about out-of-tree kernel modules licensed
under GPLv3 and if they are supposed to be able to use symbols exported
using EXPORT_SYMBOL_GPL.

Clarify that "Proprietary" means anything non-GPL2 even though the
license might be an open source license. Also disambiguate "GPL
compatible" to "GPLv2 compatible".

Signed-off-by: Uwe Kleine-König 
Signed-off-by: Jonathan Corbet 
Link: https://lore.kernel.org/r/20241115103842.585207-2-ukleinek@kernel.org

fix grammar on false-sharing.rst

2024-10-14T19:22:17+00:00

Fix slight grammar mistake on kernel-hacking/false-sharing.rst

Signed-off-by: Vishnu Sanal T 
Signed-off-by: Jonathan Corbet 
Link: https://lore.kernel.org/r/20241007191253.112697-2-t.v.s10123@gmail.com

Documentation: Add document for false sharing

2023-04-10T22:46:11+00:00

When doing performance tuning or debugging performance regressions,
more and more cases are found to be related to false sharing [1][2][3],
and the situation can be worse for newer platforms with hundreds of
CPUs. There are already many commits in current kernel specially
for mitigating the performance degradation due to false sharing.

False sharing could harm the performance silently without being
noticed, due to reasons like:
* data members of a big data structure randomly sitting together
  in one cache line
* global data of small size are linked compactly together

So it's better to make a simple document about the normal pattern
of false sharing, basic ways to mitigate it and call out to
developers to pay attention during code-writing.

[ Many thanks to Dave Hansen, Ying Huang, Tim Chen, Julie Du and
  Yu Chen for their contributions ]

[1]. https://lore.kernel.org/lkml/20220619150456.GB34471@xsang-OptiPlex-9020/
[2]. https://lore.kernel.org/lkml/20201102091543.GM31092@shao2-debian/
[3]. https://lore.kernel.org/lkml/20230307125538.818862491@linutronix.de/

Signed-off-by: Feng Tang 
Reviewed-by: Randy Dunlap 
Reviewed-by: Shakeel Butt 
Link: https://lore.kernel.org/r/20230407041235.37886-1-feng.tang@intel.com
Signed-off-by: Jonathan Corbet

docs: locking: Discourage from calling disable_irq() in atomic

2023-01-11T18:45:26+00:00

Correct the example in the documentation so that disable_irq() is not being
called in atomic context.

disable_irq() calls sleeping synchronize_irq(), it's not allowed to call
them in atomic context.

Signed-off-by: Alexander Sverdlin 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Manfred Spraul 
Cc: linux-doc@vger.kernel.org
Link: https://lore.kernel.org/lkml/87k02wbs2n.ffs@tglx/
Link: https://lore.kernel.org/r/20221212163715.830315-1-alexander.sverdlin@siemens.com