linux-toradex.git/kernel/panic.c, branch v5.19-rc1

Merge tag 'sysctl-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

2022-05-26T23:57:20+00:00

Pull sysctl updates from Luis Chamberlain:
 "For two kernel releases now kernel/sysctl.c has been being cleaned up
  slowly, since the tables were grossly long, sprinkled with tons of
  #ifdefs and all this caused merge conflicts with one susbystem or
  another.

  This tree was put together to help try to avoid conflicts with these
  cleanups going on different trees at time. So nothing exciting on this
  pull request, just cleanups.

  Thanks a lot to the Uniontech and Huawei folks for doing some of this
  nasty work"

* tag 'sysctl-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux: (28 commits)
  sched: Fix build warning without CONFIG_SYSCTL
  reboot: Fix build warning without CONFIG_SYSCTL
  kernel/kexec_core: move kexec_core sysctls into its own file
  sysctl: minor cleanup in new_dir()
  ftrace: fix building with SYSCTL=y but DYNAMIC_FTRACE=n
  fs/proc: Introduce list_for_each_table_entry for proc sysctl
  mm: fix unused variable kernel warning when SYSCTL=n
  latencytop: move sysctl to its own file
  ftrace: fix building with SYSCTL=n but DYNAMIC_FTRACE=y
  ftrace: Fix build warning
  ftrace: move sysctl_ftrace_enabled to ftrace.c
  kernel/do_mount_initrd: move real_root_dev sysctls to its own file
  kernel/delayacct: move delayacct sysctls to its own file
  kernel/acct: move acct sysctls to its own file
  kernel/panic: move panic sysctls to its own file
  kernel/lockdep: move lockdep sysctls to its own file
  mm: move page-writeback sysctls to their own file
  mm: move oom_kill sysctls to their own file
  kernel/reboot: move reboot sysctls to its own file
  sched: Move energy_aware sysctls to topology.c
  ...

Merge tag 'printk-for-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

2022-05-25T17:32:08+00:00

Pull printk updates from Petr Mladek:

 - Offload writing printk() messages on consoles to per-console
   kthreads.

   It prevents soft-lockups when an extensive amount of messages is
   printed. It was observed, for example, during boot of large systems
   with a lot of peripherals like disks or network interfaces.

   It prevents live-lockups that were observed, for example, when
   messages about allocation failures were reported and a CPU handled
   consoles instead of reclaiming the memory. It was hard to solve even
   with rate limiting because it would need to take into account the
   amount of messages and the speed of all consoles.

   It is a must to have for real time. Otherwise, any printk() might
   break latency guarantees.

   The per-console kthreads allow to handle each console on its own
   speed. Slow consoles do not longer slow down faster ones. And
   printk() does not longer unpredictably slows down various code paths.

   There are situations when the kthreads are either not available or
   not reliable, for example, early boot, suspend, or panic. In these
   situations, printk() uses the legacy mode and tries to handle
   consoles immediately.

 - Add documentation for the printk index.

* tag 'printk-for-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
  printk, tracing: fix console tracepoint
  printk: remove @console_locked
  printk: extend console_lock for per-console locking
  printk: add kthread console printers
  printk: add functions to prefer direct printing
  printk: add pr_flush()
  printk: move buffer definitions into console_emit_next_record() caller
  printk: refactor and rework printing logic
  printk: add con_printk() macro for console details
  printk: call boot_delay_msec() in printk_delay()
  printk: get caller_id/timestamp after migration disable
  printk: wake waiters for safe and NMI contexts
  printk: wake up all waiters
  printk: add missing memory barrier to wake_up_klogd()
  printk: cpu sync always disable interrupts
  printk: rename cpulock functions
  printk/index: Printk index feature documentation
  MAINTAINERS: Add printk indexing maintainers on mention of printk_index

randstruct: Reorganize Kconfigs and attribute macros

2022-05-08T08:33:06+00:00

In preparation for Clang supporting randstruct, reorganize the Kconfigs,
move the attribute macros, and generalize the feature to be named
CONFIG_RANDSTRUCT for on/off, CONFIG_RANDSTRUCT_FULL for the full
randomization mode, and CONFIG_RANDSTRUCT_PERFORMANCE for the cache-line
sized mode.

Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook 
Link: https://lore.kernel.org/r/20220503205503.3054173-4-keescook@chromium.org

printk: add functions to prefer direct printing

2022-04-22T19:30:58+00:00

Once kthread printing is available, console printing will no longer
occur in the context of the printk caller. However, there are some
special contexts where it is desirable for the printk caller to
directly print out kernel messages. Using pr_flush() to wait for
threaded printers is only possible if the caller is in a sleepable
context and the kthreads are active. That is not always the case.

Introduce printk_prefer_direct_enter() and printk_prefer_direct_exit()
functions to explicitly (and globally) activate/deactivate preferred
direct console printing. The term "direct console printing" refers to
printing to all enabled consoles from the context of the printk
caller. The term "prefer" is used because this type of printing is
only best effort. If the console is currently locked or other
printers are already actively printing, the printk caller will need
to rely on the other contexts to handle the printing.

This preferred direct printing is how all printing has been handled
until now (unless it was explicitly deferred).

When kthread printing is introduced, there may be some unanticipated
problems due to kthreads being unable to flush important messages.
In order to minimize such risks, preferred direct printing is
activated for the primary important messages when the system
experiences general types of major errors. These are:

 - emergency reboot/shutdown
 - cpu and rcu stalls
 - hard and soft lockups
 - hung tasks
 - warn
 - sysrq

Note that since kthread printing does not yet exist, no behavior
changes result from this commit. This is only implementing the
counter and marking the various places where preferred direct
printing is active.

Signed-off-by: John Ogness 
Reviewed-by: Petr Mladek 
Acked-by: Paul E. McKenney  # for RCU
Signed-off-by: Petr Mladek 
Link: https://lore.kernel.org/r/20220421212250.565456-13-john.ogness@linutronix.de

kernel/panic: move panic sysctls to its own file

2022-04-06T20:43:44+00:00

kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to places
where they actually belong.  The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.

All filesystem syctls now get reviewed by fs folks. This commit
follows the commit of fs, move the oops_all_cpu_backtrace sysctl to
its own file, kernel/panic.c.

Signed-off-by: tangmeng 
Signed-off-by: Luis Chamberlain

panic: move panic_print before kmsg dumpers

2022-03-24T02:00:35+00:00

The panic_print setting allows users to collect more information in a
panic event, like memory stats, tasks, CPUs backtraces, etc.  This is an
interesting debug mechanism, but currently the print event happens *after*
kmsg_dump(), meaning that pstore, for example, cannot collect a dmesg with
the panic_print extra information.

This patch changes that in 2 steps:

(a) The panic_print setting allows to replay the existing kernel log
    buffer to the console (bit 5), besides the extra information dump.
    This functionality makes sense only at the end of the panic()
    function.  So, we hereby allow to distinguish the two situations by a
    new boolean parameter in the function panic_print_sys_info().

(b) With the above change, we can safely call panic_print_sys_info()
    before kmsg_dump(), allowing to dump the extra information when using
    pstore or other kmsg dumpers.

The additional messages from panic_print could overwrite the oldest
messages when the buffer is full.  The only reasonable solution is to use
a large enough log buffer, hence we added an advice into the kernel
parameters documentation about that.

Link: https://lkml.kernel.org/r/20220214141308.841525-1-gpiccoli@igalia.com
Signed-off-by: Guilherme G. Piccoli 
Acked-by: Baoquan He 
Reviewed-by: Petr Mladek 
Reviewed-by: Sergey Senozhatsky 
Cc: Feng Tang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

panic: add option to dump all CPUs backtraces in panic_print

2022-03-24T02:00:35+00:00

Currently the "panic_print" parameter/sysctl allows some interesting debug
information to be printed during a panic event.  This is useful for
example in cases the user cannot kdump due to resource limits, or if the
user collects panic logs in a serial output (or pstore) and prefers a fast
reboot instead of a kdump.

Happens that currently there's no way to see all CPUs backtraces in a
panic using "panic_print" on architectures that support that.  We do have
"oops_all_cpu_backtrace" sysctl, but although partially overlapping in the
functionality, they are orthogonal in nature: "panic_print" is a panic
tuning (and we have panics without oopses, like direct calls to panic() or
maybe other paths that don't go through oops_enter() function), and the
original purpose of "oops_all_cpu_backtrace" is to provide more
information on oopses for cases in which the users desire to continue
running the kernel even after an oops, i.e., used in non-panic scenarios.

So, we hereby introduce an additional bit for "panic_print" to allow
dumping the CPUs backtraces during a panic event.

Link: https://lkml.kernel.org/r/20211109202848.610874-3-gpiccoli@igalia.com
Signed-off-by: Guilherme G. Piccoli 
Reviewed-by: Feng Tang 
Cc: Iurii Zaikin 
Cc: Kees Cook 
Cc: Luis Chamberlain 
Cc: Samuel Iglesias Gonsalvez 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

panic: unset panic_on_warn inside panic()

2022-03-24T02:00:34+00:00

In the current code, the following three places need to unset
panic_on_warn before calling panic() to avoid recursive panics:

kernel/kcsan/report.c: print_report()
kernel/sched/core.c: __schedule_bug()
mm/kfence/report.c: kfence_report_error()

In order to avoid copy-pasting "panic_on_warn = 0" all over the places,
it is better to move it inside panic() and then remove it from the other
places.

Link: https://lkml.kernel.org/r/1644324666-15947-4-git-send-email-yangtiezhu@loongson.cn
Signed-off-by: Tiezhu Yang 
Reviewed-by: Marco Elver 
Cc: Andrey Ryabinin 
Cc: Baoquan He 
Cc: Jonathan Corbet 
Cc: Xuefeng Li 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

panic: remove oops_id

2022-01-20T06:52:55+00:00

The oops id has been added as part of the end of trace marker for the
kerneloops.org project.  The id is used to automatically identify
duplicate submissions of the same report.  Identical looking reports
with different a id can be considered as the same oops occurred again.

The early initialisation of the oops_id can create a warning if the
random core is not yet fully initialized.  On PREEMPT_RT it is
problematic if the id is initialized on demand from non preemptible
context.

The kernel oops project is not available since 2017.  Remove the oops_id
and use 0 in the output in case parser rely on it.

Link: https://bugs.debian.org/953172
Link: https://lkml.kernel.org/r/Ybdi16aP2NEugWHq@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior 
Cc: Arjan van de Ven 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

panic: use error_report_end tracepoint on warnings

2022-01-20T06:52:55+00:00

Introduce the error detector "warning" to the error_report event and use
the error_report_end tracepoint at the end of a warning report.

This allows in-kernel tests but also userspace to more easily determine
if a warning occurred without polling kernel logs.

[akpm@linux-foundation.org: add comma to enum list, per Andy]

Link: https://lkml.kernel.org/r/20211115085630.1756817-1-elver@google.com
Signed-off-by: Marco Elver 
Cc: Steven Rostedt 
Cc: Ingo Molnar 
Cc: Alexander Potapenko 
Cc: Petr Mladek 
Cc: Luis Chamberlain 
Cc: Wei Liu 
Cc: Mike Rapoport 
Cc: Arnd Bergmann 
Cc: John Ogness 
Cc: Andy Shevchenko 
Cc: Alexander Popov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds