linux.git/lib/Kconfig.debug, branch v6.6.132

Remove WARN_ALL_UNSEEDED_RANDOM kernel config option

2026-03-04T12:21:00+00:00

[ Upstream commit 7dff99b354601dd01829e1511711846e04340a69 ]

This config option goes way back - it used to be an internal debug
option to random.c (at that point called DEBUG_RANDOM_BOOT), then was
renamed and exposed as a config option as CONFIG_WARN_UNSEEDED_RANDOM,
and then further renamed to the current CONFIG_WARN_ALL_UNSEEDED_RANDOM.

It was all done with the best of intentions: the more limited
rate-limited reports were reporting some cases, but if you wanted to see
all the gory details, you'd enable this "ALL" option.

However, it turns out - perhaps not surprisingly - that when people
don't care about and fix the first rate-limited cases, they most
certainly don't care about any others either, and so warning about all
of them isn't actually helping anything.

And the non-ratelimited reporting causes problems, where well-meaning
people enable debug options, but the excessive flood of messages that
nobody cares about will hide actual real information when things go
wrong.

I just got a kernel bug report (which had nothing to do with randomness)
where two thirds of the the truncated dmesg was just variations of

   random: get_random_u32 called from __get_random_u32_below+0x10/0x70 with crng_init=0

and in the process early boot messages had been lost (in addition to
making the messages that _hadn't_ been lost harder to read).

The proper way to find these things for the hypothetical developer that
cares - if such a person exists - is almost certainly with boot time
tracing.  That gives you the option to get call graphs etc too, which is
likely a requirement for fixing any problems anyway.

See Documentation/trace/boottime-trace.rst for that option.

And if we for some reason do want to re-introduce actual printing of
these things, it will need to have some uniqueness filtering rather than
this "just print it all" model.

Fixes: cc1e127bfa95 ("random: remove ratelimiting for in-kernel unseeded randomness")
Acked-by: Jason Donenfeld 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

Kunit to check the longest symbol length

2025-07-06T09:00:16+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: Shuah Khan 
Signed-off-by: Greg Kroah-Hartman

lockdep: Fix upper limit for LOCKDEP_*_BITS configs

2025-02-17T08:40:03+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

lib/Kconfig.debug: fix grammar in RUST_BUILD_ASSERT_ALLOW

2024-11-01T00:58:18+00:00

[ Upstream commit ab8851431bef5cc44f0f3f0da112e883fd4d0df5 ]

Just a grammar fix in lib/Kconfig.debug, under the config option
RUST_BUILD_ASSERT_ALLOW.

Reported-by: Miguel Ojeda 
Closes: https://github.com/Rust-for-Linux/linux/issues/1006
Fixes: ecaa6ddff2fd ("rust: add `build_error` crate")
Signed-off-by: Timo Grautstueck 
Link: https://lore.kernel.org/r/20241006140244.5509-1-timo.grautstueck@web.de
Signed-off-by: Miguel Ojeda 
Signed-off-by: Sasha Levin

bpf, kconfig: Fix DEBUG_INFO_BTF_MODULES Kconfig definition

2024-05-17T10:01:59+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

lib/Kconfig.debug: TEST_IOV_ITER depends on MMU

2024-03-01T12:34:59+00:00

commit 1eb1e984379e2da04361763f66eec90dd75cf63e upstream.

Trying to run the iov_iter unit test on a nommu system such as the qemu
kc705-nommu emulation results in a crash.

    KTAP version 1
    # Subtest: iov_iter
    # module: kunit_iov_iter
    1..9
BUG: failure at mm/nommu.c:318/vmap()!
Kernel panic - not syncing: BUG!

The test calls vmap() directly, but vmap() is not supported on nommu
systems, causing the crash.  TEST_IOV_ITER therefore needs to depend on
MMU.

Link: https://lkml.kernel.org/r/20240208153010.1439753-1-linux@roeck-us.net
Fixes: 2d71340ff1d4 ("iov_iter: Kunit tests for copying to/from an iterator")
Signed-off-by: Guenter Roeck 
Cc: David Howells 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

cred: get rid of CONFIG_DEBUG_CREDENTIALS

2023-12-20T16:01:51+00:00

commit ae1914174a63a558113e80d24ccac2773f9f7b2b upstream.

This code is rarely (never?) enabled by distros, and it hasn't caught
anything in decades. Let's kill off this legacy debug code.

Suggested-by: Linus Torvalds 
Signed-off-by: Jens Axboe 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

iov_iter: Kunit tests for copying to/from an iterator

2023-09-09T22:11:49+00:00

Add some kunit tests for page extraction for ITER_BVEC, ITER_KVEC and
ITER_XARRAY type iterators.  ITER_UBUF and ITER_IOVEC aren't dealt with
as they require userspace VM interaction.  ITER_DISCARD isn't dealt with
either as that does nothing.

Signed-off-by: David Howells 
Cc: Christoph Hellwig 
Cc: Christian Brauner 
Cc: Jens Axboe 
Cc: Al Viro 
Cc: David Hildenbrand 
Cc: John Hubbard 
Signed-off-by: Linus Torvalds

Merge tag 'riscv-for-linus-6.6-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

2023-09-01T15:09:48+00:00

Pull RISC-V updates from Palmer Dabbelt:

 - Support for the new "riscv,isa-extensions" and "riscv,isa-base"
   device tree interfaces for probing extensions

 - Support for userspace access to the performance counters

 - Support for more instructions in kprobes

 - Crash kernels can be allocated above 4GiB

 - Support for KCFI

 - Support for ELFs in !MMU configurations

 - ARCH_KMALLOC_MINALIGN has been reduced to 8

 - mmap() defaults to sv48-sized addresses, with longer addresses hidden
   behind a hint (similar to Arm and Intel)

 - Also various fixes and cleanups

* tag 'riscv-for-linus-6.6-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (51 commits)
  lib/Kconfig.debug: Restrict DEBUG_INFO_SPLIT for RISC-V
  riscv: support PREEMPT_DYNAMIC with static keys
  riscv: Move create_tmp_mapping() to init sections
  riscv: Mark KASAN tmp* page tables variables as static
  riscv: mm: use bitmap_zero() API
  riscv: enable DEBUG_FORCE_FUNCTION_ALIGN_64B
  riscv: remove redundant mv instructions
  RISC-V: mm: Document mmap changes
  RISC-V: mm: Update pgtable comment documentation
  RISC-V: mm: Add tests for RISC-V mm
  RISC-V: mm: Restrict address space for sv39,sv48,sv57
  riscv: enable DMA_BOUNCE_UNALIGNED_KMALLOC for !dma_coherent
  riscv: allow kmalloc() caches aligned to the smallest value
  riscv: support the elf-fdpic binfmt loader
  binfmt_elf_fdpic: support 64-bit systems
  riscv: Allow CONFIG_CFI_CLANG to be selected
  riscv/purgatory: Disable CFI
  riscv: Add CFI error handling
  riscv: Add ftrace_stub_graph
  riscv: Add types to indirectly called assembly functions
  ...

lib/Kconfig.debug: Restrict DEBUG_INFO_SPLIT for RISC-V

2023-08-31T07:18:37+00:00

When building for ARCH=riscv using LLVM < 14, there is an error with
CONFIG_DEBUG_INFO_SPLIT=y:

  error: A dwo section may not contain relocations

This was worked around in LLVM 15 by disallowing '-gsplit-dwarf' with
'-mrelax' (the default), so CONFIG_DEBUG_INFO_SPLIT is not selectable
with newer versions of LLVM:

  $ clang --target=riscv64-linux-gnu -gsplit-dwarf -c -o /dev/null -x c /dev/null
  clang: error: -gsplit-dwarf is unsupported with RISC-V linker relaxation (-mrelax)

GCC silently had a similar issue that was resolved with GCC 12.x.
Restrict CONFIG_DEBUG_INFO_SPLIT for RISC-V when using LLVM or GCC <
12.x to avoid these known issues.

Link: https://github.com/ClangBuiltLinux/linux/issues/1914
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99090
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/all/202308090204.9yZffBWo-lkp@intel.com/
Signed-off-by: Nathan Chancellor 
Reviewed-by: Fangrui Song 
Reviewed-by: Nick Desaulniers 
Link: https://lore.kernel.org/r/20230816-riscv-debug_info_split-v1-1-d1019d6ccc11@kernel.org
Signed-off-by: Palmer Dabbelt