kernel/linux.git/lib/Kconfig.debug, branch v6.1.168

Kunit to check the longest symbol length

2025-07-06T08:58:03+00:00

commit c104c16073b7fdb3e4eae18f66f4009f6b073d6f upstream. The longest length of a symbol (KSYM_NAME_LEN) was increased to 512 in the reference [1]. This patch adds kunit test suite to check the longest symbol length. These tests verify that the longest symbol length defined is supported. This test can also help other efforts for longer symbol length, like [2]. The test suite defines one symbol with the longest possible length. The first test verify that functions with names of the created symbol, can be called or not. The second test, verify that the symbols are created (or not) in the kernel symbol table. [1] https://lore.kernel.org/lkml/20220802015052.10452-6-ojeda@kernel.org/ [2] https://lore.kernel.org/lkml/20240605032120.3179157-1-song@kernel.org/ Link: https://lore.kernel.org/r/20250302221518.76874-1-sergio.collado@gmail.com Tested-by: Martin Rodriguez Reboredo Reviewed-by: Shuah Khan Reviewed-by: Rae Moar Signed-off-by: Sergio González Collado Link: https://github.com/Rust-for-Linux/linux/issues/504 Reviewed-by: Rae Moar Acked-by: David Gow Signed-off-by: Shuah Khan Signed-off-by: Greg Kroah-Hartman

lockdep: Fix upper limit for LOCKDEP_*_BITS configs

2025-02-21T12:49:29+00:00

[ Upstream commit e638072e61726cae363d48812815197a2a0e097f ] Lockdep has a set of configs used to determine the size of the static arrays that it uses. However, the upper limit that was initially setup for these configs is too high (30 bit shift). This equates to several GiB of static memory for individual symbols. Using such high values leads to linker errors: $ make defconfig $ ./scripts/config -e PROVE_LOCKING --set-val LOCKDEP_BITS 30 $ make olddefconfig all [...] ld: kernel image bigger than KERNEL_IMAGE_SIZE ld: section .bss VMA wraps around address space Adjust the upper limits to the maximum values that avoid these issues. The need for anything more, likely points to a problem elsewhere. Note that LOCKDEP_CHAINS_BITS was intentionally left out as its upper limit had a different symptom and has already been fixed [1]. Reported-by: J. R. Okajima Closes: https://lore.kernel.org/all/30795.1620913191@jrobl/ [1] Cc: Peter Zijlstra Cc: Boqun Feng Cc: Ingo Molnar Cc: Waiman Long Cc: Will Deacon Acked-by: Waiman Long Signed-off-by: Carlos Llamas Signed-off-by: Boqun Feng Link: https://lore.kernel.org/r/20241024183631.643450-2-cmllamas@google.com Signed-off-by: Sasha Levin

bpf, kconfig: Fix DEBUG_INFO_BTF_MODULES Kconfig definition

2024-05-17T09:55:56+00:00

[ Upstream commit 229087f6f1dc2d0c38feba805770f28529980ec0 ] Turns out that due to CONFIG_DEBUG_INFO_BTF_MODULES not having an explicitly specified "menu item name" in Kconfig, it's basically impossible to turn it off (see [0]). This patch fixes the issue by defining menu name for CONFIG_DEBUG_INFO_BTF_MODULES, which makes it actually adjustable and independent of CONFIG_DEBUG_INFO_BTF, in the sense that one can have DEBUG_INFO_BTF=y and DEBUG_INFO_BTF_MODULES=n. We still keep it as defaulting to Y, of course. Fixes: 5f9ae91f7c0d ("kbuild: Build kernel module BTFs if BTF is enabled and pahole supports it") Reported-by: Vincent Li Signed-off-by: Andrii Nakryiko Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/CAK3+h2xiFfzQ9UXf56nrRRP=p1+iUxGoEP5B+aq9MDT5jLXDSg@mail.gmail.com [0] Link: https://lore.kernel.org/bpf/20240404220344.3879270-1-andrii@kernel.org Signed-off-by: Sasha Levin

btf, scripts: Exclude Rust CUs with pahole

2024-01-20T10:50:10+00:00

commit c1177979af9c616661a126a80dd486ad0543b836 upstream. Version 1.24 of pahole has the capability to exclude compilation units (CUs) of specific languages [1] [2]. Rust, as of writing, is not currently supported by pahole and if it's used with a build that has BTF debugging enabled it results in malformed kernel and module binaries [3]. So it's better for pahole to exclude Rust CUs until support for it arrives. Co-developed-by: Eric Curtin Signed-off-by: Eric Curtin Signed-off-by: Martin Rodriguez Reboredo Signed-off-by: Daniel Borkmann Tested-by: Eric Curtin Reviewed-by: Neal Gompa Acked-by: Miguel Ojeda Acked-by: Arnaldo Carvalho de Melo Link: https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?id=49358dfe2aaae4e90b072332c3e324019826783f [1] Link: https://git.kernel.org/pub/scm/devel/pahole/pahole.git/commit/?id=8ee363790b7437283c53090a85a9fec2f0b0fbc4 [2] Link: https://github.com/Rust-for-Linux/linux/issues/735 [3] Link: https://lore.kernel.org/bpf/20230111152050.559334-1-yakoyoku@gmail.com Signed-off-by: Jiri Olsa Signed-off-by: Greg Kroah-Hartman

lib/Kconfig.debug: do not enable DEBUG_PREEMPT by default

2023-10-25T10:03:02+00:00

commit cc6003916ed46d7a67d91ee32de0f9138047d55f upstream. In workloads where this_cpu operations are frequently performed, enabling DEBUG_PREEMPT may result in significant increase in runtime overhead due to frequent invocation of __this_cpu_preempt_check() function. This can be demonstrated through benchmarks such as hackbench where this configuration results in a 10% reduction in performance, primarily due to the added overhead within memcg charging path. Therefore, do not to enable DEBUG_PREEMPT by default and make users aware of its potential impact on performance in some workloads. hackbench-process-sockets debug_preempt no_debug_preempt Amean 1 0.4743 ( 0.00%) 0.4295 * 9.45%* Amean 4 1.4191 ( 0.00%) 1.2650 * 10.86%* Amean 7 2.2677 ( 0.00%) 2.0094 * 11.39%* Amean 12 3.6821 ( 0.00%) 3.2115 * 12.78%* Amean 21 6.6752 ( 0.00%) 5.7956 * 13.18%* Amean 30 9.6646 ( 0.00%) 8.5197 * 11.85%* Amean 48 15.3363 ( 0.00%) 13.5559 * 11.61%* Amean 79 24.8603 ( 0.00%) 22.0597 * 11.27%* Amean 96 30.1240 ( 0.00%) 26.8073 * 11.01%* Link: https://lkml.kernel.org/r/20230121033942.350387-1-42.hyeyoo@gmail.com Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Acked-by: Roman Gushchin Acked-by: Mel Gorman Acked-by: Davidlohr Bueso Cc: Ben Segall Cc: Christoph Lameter Cc: Daniel Bristot de Oliveira Cc: David Rientjes Cc: Dennis Zhou Cc: Dietmar Eggemann Cc: Ingo Molnar Cc: Johannes Weiner Cc: Joonsoo Kim Cc: Juri Lelli Cc: Matthew Wilcox Cc: Muchun Song Cc: Pekka Enberg Cc: Peter Zijlstra Cc: Shakeel Butt Cc: Steven Rostedt (Google) Cc: Tejun Heo Cc: Valentin Schneider Cc: Vincent Guittot Cc: Vlastimil Babka Signed-off-by: Andrew Morton Cc: Luiz Capitulino Signed-off-by: Greg Kroah-Hartman

test_kprobes: Fix implicit declaration error of test_kprobes

2023-01-07T10:11:55+00:00

commit 63a4dc0a0bb0e9bfeb2c88ccda81abdde4cdd6b8 upstream. If KPROBES_SANITY_TEST and ARCH_CORRECT_STACKTRACE_ON_KRETPROBE is enabled, but STACKTRACE is not set. Build failed as below: lib/test_kprobes.c: In function ‘stacktrace_return_handler’: lib/test_kprobes.c:228:8: error: implicit declaration of function ‘stack_trace_save’; did you mean ‘stacktrace_driver’? [-Werror=implicit-function-declaration] ret = stack_trace_save(stack_buf, STACK_BUF_SIZE, 0); ^~~~~~~~~~~~~~~~ stacktrace_driver cc1: all warnings being treated as errors scripts/Makefile.build:250: recipe for target 'lib/test_kprobes.o' failed make[2]: *** [lib/test_kprobes.o] Error 1 To fix this error, Select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE is enabled. Link: https://lore.kernel.org/all/20221121030620.63181-1-hucool.lihua@huawei.com/ Fixes: 1f6d3a8f5e39 ("kprobes: Add a test case for stacktrace from kretprobe handler") Cc: stable@vger.kernel.org Signed-off-by: Li Hua Acked-by: Masami Hiramatsu (Google) Signed-off-by: Masami Hiramatsu (Google) Signed-off-by: Greg Kroah-Hartman

Merge tag 'mm-hotfixes-stable-2022-12-02' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-12-02T21:39:38+00:00

Pull misc hotfixes from Andrew Morton: "15 hotfixes, 11 marked cc:stable. Only three or four of the latter address post-6.0 issues, which is hopefully a sign that things are converging" * tag 'mm-hotfixes-stable-2022-12-02' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: revert "kbuild: fix -Wimplicit-function-declaration in license_is_gpl_compatible" Kconfig.debug: provide a little extra FRAME_WARN leeway when KASAN is enabled drm/amdgpu: temporarily disable broken Clang builds due to blown stack-frame mm/khugepaged: invoke MMU notifiers in shmem/file collapse paths mm/khugepaged: fix GUP-fast interaction by sending IPI mm/khugepaged: take the right locks for page table retraction mm: migrate: fix THP's mapcount on isolation mm: introduce arch_has_hw_nonleaf_pmd_young() mm: add dummy pmd_young() for architectures not having it mm/damon/sysfs: fix wrong empty schemes assumption under online tuning in damon_sysfs_set_schemes() tools/vm/slabinfo-gnuplot: use "grep -E" instead of "egrep" nilfs2: fix NULL pointer dereference in nilfs_palloc_commit_free_entry() hugetlb: don't delete vma_lock in hugetlb MADV_DONTNEED processing madvise: use zap_page_range_single for madvise dontneed mm: replace VM_WARN_ON to pr_warn if the node is offline with __GFP_THISNODE

error-injection: Add prompt for function error injection

2022-12-01T21:14:21+00:00

The config to be able to inject error codes into any function annotated with ALLOW_ERROR_INJECTION() is enabled when FUNCTION_ERROR_INJECTION is enabled. But unfortunately, this is always enabled on x86 when KPROBES is enabled, and there's no way to turn it off. As kprobes is useful for observability of the kernel, it is useful to have it enabled in production environments. But error injection should be avoided. Add a prompt to the config to allow it to be disabled even when kprobes is enabled, and get rid of the "def_bool y". This is a kernel debug feature (it's in Kconfig.debug), and should have never been something enabled by default. Cc: stable@vger.kernel.org Fixes: 540adea3809f6 ("error-injection: Separate error-injection from kprobe") Signed-off-by: Steven Rostedt (Google) Signed-off-by: Linus Torvalds

Kconfig.debug: provide a little extra FRAME_WARN leeway when KASAN is enabled

2022-11-30T22:49:42+00:00

When enabled, KASAN enlarges function's stack-frames. Pushing quite a few over the current threshold. This can mainly be seen on 32-bit architectures where the present limit (when !GCC) is a lowly 1024-Bytes. Link: https://lkml.kernel.org/r/20221125120750.3537134-3-lee@kernel.org Signed-off-by: Lee Jones Acked-by: Arnd Bergmann Cc: Alex Deucher Cc: "Christian König" Cc: Daniel Vetter Cc: David Airlie Cc: Harry Wentland Cc: Leo Li Cc: Maarten Lankhorst Cc: Maxime Ripard Cc: Nathan Chancellor Cc: Nick Desaulniers Cc: "Pan, Xinhui" Cc: Rodrigo Siqueira Cc: Thomas Zimmermann Cc: Tom Rix Cc: Signed-off-by: Andrew Morton

test_kprobes: fix implicit declaration error of test_kprobes

2022-11-23T02:50:45+00:00

If KPROBES_SANITY_TEST and ARCH_CORRECT_STACKTRACE_ON_KRETPROBE is enabled, but STACKTRACE is not set. Build failed as below: lib/test_kprobes.c: In function `stacktrace_return_handler': lib/test_kprobes.c:228:8: error: implicit declaration of function `stack_trace_save'; did you mean `stacktrace_driver'? [-Werror=implicit-function-declaration] ret = stack_trace_save(stack_buf, STACK_BUF_SIZE, 0); ^~~~~~~~~~~~~~~~ stacktrace_driver cc1: all warnings being treated as errors scripts/Makefile.build:250: recipe for target 'lib/test_kprobes.o' failed make[2]: *** [lib/test_kprobes.o] Error 1 To fix this error, Select STACKTRACE if ARCH_CORRECT_STACKTRACE_ON_KRETPROBE is enabled. Link: https://lkml.kernel.org/r/20221121030620.63181-1-hucool.lihua@huawei.com Fixes: 1f6d3a8f5e39 ("kprobes: Add a test case for stacktrace from kretprobe handler") Signed-off-by: Li Hua Acked-by: Masami Hiramatsu (Google) Cc: Steven Rostedt (VMware) Signed-off-by: Andrew Morton