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: cc1e127bfa ("random: remove ratelimiting for in-kernel unseeded randomness")
Acked-by: Jason Donenfeld <Jason@zx2c4.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The softlockup_panic sysctl is currently a binary option: panic
immediately or never panic on soft lockups.
Panicking on any soft lockup, regardless of duration, can be overly
aggressive for brief stalls that may be caused by legitimate operations.
Conversely, never panicking may allow severe system hangs to persist
undetected.
Extend softlockup_panic to accept an integer threshold, allowing the
kernel to panic only when the normalized lockup duration exceeds N
watchdog threshold periods. This provides finer-grained control to
distinguish between transient delays and persistent system failures.
The accepted values are:
- 0: Don't panic (unchanged)
- 1: Panic when duration >= 1 * threshold (20s default, original behavior)
- N > 1: Panic when duration >= N * threshold (e.g., 2 = 40s, 3 = 60s.)
The original behavior is preserved for values 0 and 1, maintaining full
backward compatibility while allowing systems to tolerate brief lockups
while still catching severe, persistent hangs.
[lirongqing@baidu.com: v2]
Link: https://lkml.kernel.org/r/20251218074300.4080-1-lirongqing@baidu.com
Link: https://lkml.kernel.org/r/20251216074521.2796-1-lirongqing@baidu.com
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The hung_task_panic sysctl is currently a blunt instrument: it's all or
nothing.
Panicking on a single hung task can be an overreaction to a transient
glitch. A more reliable indicator of a systemic problem is when
multiple tasks hang simultaneously.
Extend hung_task_panic to accept an integer threshold, allowing the
kernel to panic only when N hung tasks are detected in a single scan.
This provides finer control to distinguish between isolated incidents
and system-wide failures.
The accepted values are:
- 0: Don't panic (unchanged)
- 1: Panic on the first hung task (unchanged)
- N > 1: Panic after N hung tasks are detected in a single scan
The original behavior is preserved for values 0 and 1, maintaining full
backward compatibility.
[lance.yang@linux.dev: new changelog]
Link: https://lkml.kernel.org/r/20251015063615.2632-1-lirongqing@baidu.com
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Tested-by: Lance Yang <lance.yang@linux.dev>
Acked-by: Andrew Jeffery <andrew@codeconstruct.com.au> [aspeed_g5_defconfig]
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Florian Wesphal <fw@strlen.de>
Cc: Jakub Kacinski <kuba@kernel.org>
Cc: Jason A. Donenfeld <jason@zx2c4.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Simon Horman <horms@kernel.org>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm: Rework generic PTDUMP configs", v3.
The series reworks generic PTDUMP configs before eventually renaming them
after some basic cleanups first.
This patch (of 5):
The platforms that support GENERIC_PTDUMP select the config explicitly.
But enabling this feature on platforms that don't really support - does
nothing or might cause a build failure. Hence just drop GENERIC_PTDUMP
from generic debug.config
Link: https://lkml.kernel.org/r/20250226122404.1927473-1-anshuman.khandual@arm.com
Link: https://lkml.kernel.org/r/20250226122404.1927473-2-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Commit 0aaa8977ac ("configs: introduce debug.config for CI-like setup")
added CONFIG_PROVE_RCU_LIST=y to the common CI config,
but RCU_EXPERT is not set, and it's a dependency for
CONFIG_PROVE_RCU_LIST=y. Make sure CIs take advantage
of CONFIG_PROVE_RCU_LIST=y, recent fixes in networking
indicate that it does catch bugs.
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20241016011144.3058445-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The debug.config file is really great to easily enable a bunch of
general debugging features on a CI-like setup. But it would be great to
also include core networking debugging config.
A few CI's validating features from the Net tree also enable a few other
debugging options on top of debug.config. A small selection is quite
generic for the whole net tree. They validate some assumptions in
different parts of the core net tree. As suggested by Jakub Kicinski in
[1], having them added to this debug.config file would help other CIs
using network features to find bugs in this area.
Note that the two REFCNT configs also select REF_TRACKER, which doesn't
seem to be an issue.
Link: https://lore.kernel.org/netdev/20240202093148.33bd2b14@kernel.org/T/ [1]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20240212-kconfig-debug-enable-net-v1-1-fb026de8174c@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Currently the Kconfig fragments in kernel/configs and arch/*/configs
that aren't used internally aren't discoverable through "make help",
which consists of hard-coded lists of config fragments. Instead, list
all the fragment targets that have a "# Help: " comment prefix so the
targets can be generated dynamically.
Add logic to the Makefile to search for and display the fragment and
comment. Add comments to fragments that are intended to be direct targets.
Signed-off-by: Kees Cook <keescook@chromium.org>
Co-developed-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Previously, I failed to realize that Kees' patch [1] has not been merged
into the mainline yet, and dropped DEBUG_INFO=y too eagerly from the
mainline. As the results, "make debug.config" won't be able to flip
DEBUG_INFO=n from the existing .config. This should close the gaps of a
few weeks before Kees' patch is there, and work regardless of their
merging status anyway.
Link: https://lore.kernel.org/all/20220125075126.891825-1-keescook@chromium.org/ [1]
Link: https://lkml.kernel.org/r/20220308153524.8618-1-quic_qiancai@quicinc.com
Signed-off-by: Qian Cai <quic_qiancai@quicinc.com>
Reported-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
CONFIG_DEBUG_INFO can't be set by user directly, so set
CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y instead.
Otherwise, we end up with no debuginfo in vmlinux which is a big no-no
for kernel debugging.
Link: https://lkml.kernel.org/r/20220301202920.18488-1-quic_qiancai@quicinc.com
Signed-off-by: Qian Cai <quic_qiancai@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some general debugging features like kmemleak, KASAN, lockdep, UBSAN etc
help fix many viruses like a microscope. On the other hand, those
features are scatter around and mixed up with more situational debugging
options making them difficult to consume properly. This cold help
amplify the general debugging/testing efforts and help establish
sensitive default values for those options across the broad. This could
also help different distros to collaborate on maintaining debug-flavored
kernels.
The config is based on years' experiences running daily CI inside the
largest enterprise Linux distro company to seek regressions on
linux-next builds on different bare-metal and virtual platforms. It can
be used for example,
$ make ARCH=arm64 defconfig debug.config
Since KASAN and KCSAN can't be enabled together, we will need to create
a separate one for KCSAN later as well.
Link: https://lkml.kernel.org/r/20211115134754.7334-1-quic_qiancai@quicinc.com
Signed-off-by: Qian Cai <quic_qiancai@quicinc.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Marco Elver <elver@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: "Stephen Rothwell" <sfr@canb.auug.org.au>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
