From: Andrew Morton <akpm@linux-foundation.org>
To: yzaikin@google.com,siglesias@igalia.com,mcgrof@kernel.org,keescook@chromium.org,feng.tang@intel.com,gpiccoli@igalia.com,akpm@linux-foundation.org,patches@lists.linux.dev,linux-mm@kvack.org,mm-commits@vger.kernel.org,torvalds@linux-foundation.org,akpm@linux-foundation.org
Subject: [patch 36/41] panic: add option to dump all CPUs backtraces in panic_print
Date: Wed, 23 Mar 2022 16:07:06 -0700 [thread overview]
Message-ID: <20220323230707.20A52C340E9@smtp.kernel.org> (raw)
In-Reply-To: <20220323160453.65922ced539cbf445b191555@linux-foundation.org>
From: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Subject: panic: add option to dump all CPUs backtraces in panic_print
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 <gpiccoli@igalia.com>
Reviewed-by: Feng Tang <feng.tang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
Documentation/admin-guide/kernel-parameters.txt | 1 +
Documentation/admin-guide/sysctl/kernel.rst | 1 +
kernel/panic.c | 4 ++++
3 files changed, 6 insertions(+)
--- a/Documentation/admin-guide/kernel-parameters.txt~panic-add-option-to-dump-all-cpus-backtraces-in-panic_print
+++ a/Documentation/admin-guide/kernel-parameters.txt
@@ -3726,6 +3726,7 @@
bit 3: print locks info if CONFIG_LOCKDEP is on
bit 4: print ftrace buffer
bit 5: print all printk messages in buffer
+ bit 6: print all CPUs backtrace (if available in the arch)
panic_on_taint= Bitmask for conditionally calling panic() in add_taint()
Format: <hex>[,nousertaint]
--- a/Documentation/admin-guide/sysctl/kernel.rst~panic-add-option-to-dump-all-cpus-backtraces-in-panic_print
+++ a/Documentation/admin-guide/sysctl/kernel.rst
@@ -807,6 +807,7 @@ bit 2 print timer info
bit 3 print locks info if ``CONFIG_LOCKDEP`` is on
bit 4 print ftrace buffer
bit 5 print all printk messages in buffer
+bit 6 print all CPUs backtrace (if available in the arch)
===== ============================================
So for example to print tasks and memory info on panic, user can::
--- a/kernel/panic.c~panic-add-option-to-dump-all-cpus-backtraces-in-panic_print
+++ a/kernel/panic.c
@@ -66,6 +66,7 @@ EXPORT_SYMBOL_GPL(panic_timeout);
#define PANIC_PRINT_LOCK_INFO 0x00000008
#define PANIC_PRINT_FTRACE_INFO 0x00000010
#define PANIC_PRINT_ALL_PRINTK_MSG 0x00000020
+#define PANIC_PRINT_ALL_CPU_BT 0x00000040
unsigned long panic_print;
ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
@@ -152,6 +153,9 @@ static void panic_print_sys_info(void)
if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
console_flush_on_panic(CONSOLE_REPLAY_ALL);
+ if (panic_print & PANIC_PRINT_ALL_CPU_BT)
+ trigger_all_cpu_backtrace();
+
if (panic_print & PANIC_PRINT_TASK_INFO)
show_state();
_
next prev parent reply other threads:[~2022-03-23 23:07 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-23 23:04 incoming Andrew Morton
2022-03-23 23:05 ` [patch 01/41] proc: alloc PATH_MAX bytes for /proc/${pid}/fd/ symlinks Andrew Morton
2022-03-23 23:05 ` [patch 02/41] proc/vmcore: fix possible deadlock on concurrent mmap and read Andrew Morton
2022-03-23 23:05 ` [patch 03/41] proc/vmcore: fix vmcore_alloc_buf() kernel-doc comment Andrew Morton
2022-03-23 23:05 ` [patch 04/41] linux/types.h: remove unnecessary __bitwise__ Andrew Morton
2022-03-23 23:05 ` [patch 05/41] Documentation/sparse: add hints about __CHECKER__ Andrew Morton
2022-03-23 23:05 ` [patch 06/41] kernel/ksysfs.c: use helper macro __ATTR_RW Andrew Morton
2022-03-23 23:05 ` [patch 07/41] Kconfig.debug: make DEBUG_INFO selectable from a choice Andrew Morton
2022-03-23 23:05 ` [patch 08/41] include: drop pointless __compiler_offsetof indirection Andrew Morton
2022-03-23 23:05 ` [patch 09/41] ilog2: force inlining of __ilog2_u32() and __ilog2_u64() Andrew Morton
2022-03-23 23:05 ` [patch 10/41] bitfield: add explicit inclusions to the example Andrew Morton
2022-03-23 23:05 ` [patch 11/41] lib/Kconfig.debug: add ARCH dependency for FUNCTION_ALIGN option Andrew Morton
2022-03-23 23:05 ` [patch 12/41] lib: bitmap: fix many kernel-doc warnings Andrew Morton
2022-03-23 23:05 ` [patch 13/41] checkpatch: prefer MODULE_LICENSE("GPL") over MODULE_LICENSE("GPL v2") Andrew Morton
2022-03-23 23:05 ` [patch 14/41] checkpatch: add --fix option for some TRAILING_STATEMENTS Andrew Morton
2022-03-23 23:06 ` [patch 15/41] checkpatch: add early_param exception to blank line after struct/function test Andrew Morton
2022-03-23 23:06 ` [patch 16/41] checkpatch: use python3 to find codespell dictionary Andrew Morton
2022-03-23 23:06 ` [patch 17/41] init: use ktime_us_delta() to make initcall_debug log more precise Andrew Morton
2022-03-23 23:06 ` [patch 18/41] init.h: improve __setup and early_param documentation Andrew Morton
2022-03-23 23:06 ` [patch 19/41] init/main.c: return 1 from handled __setup() functions Andrew Morton
2022-03-23 23:06 ` [patch 20/41] fs/pipe: use kvcalloc to allocate a pipe_buffer array Andrew Morton
2022-03-23 23:06 ` [patch 21/41] fs/pipe.c: local vars have to match types of proper pipe_inode_info fields Andrew Morton
2022-03-23 23:06 ` [patch 22/41] minix: fix bug when opening a file with O_DIRECT Andrew Morton
2022-03-23 23:06 ` [patch 23/41] fat: use pointer to simple type in put_user() Andrew Morton
2022-03-23 23:06 ` [patch 24/41] cgroup: use irqsave in cgroup_rstat_flush_locked() Andrew Morton
2022-03-23 23:06 ` [patch 25/41] kexec: make crashk_res, crashk_low_res and crash_notes symbols always visible Andrew Morton
2022-03-23 23:06 ` [patch 26/41] riscv: mm: init: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef Andrew Morton
2022-03-23 23:06 ` [patch 27/41] x86/setup: " Andrew Morton
2022-03-23 23:06 ` [patch 28/41] arm64: mm: " Andrew Morton
2022-03-23 23:06 ` [patch 29/41] docs: kdump: update description about sysfs file system support Andrew Morton
2022-03-23 23:06 ` [patch 30/41] docs: kdump: add scp example to write out the dump file Andrew Morton
2022-03-23 23:06 ` [patch 31/41] panic: unset panic_on_warn inside panic() Andrew Morton
2022-03-23 23:06 ` [patch 32/41] ubsan: no need to unset panic_on_warn in ubsan_epilogue() Andrew Morton
2022-03-23 23:06 ` [patch 33/41] kasan: no need to unset panic_on_warn in end_report() Andrew Morton
2022-03-23 23:07 ` [patch 34/41] taskstats: remove unneeded dead assignment Andrew Morton
2022-03-23 23:07 ` [patch 35/41] docs: sysctl/kernel: add missing bit to panic_print Andrew Morton
2022-03-23 23:07 ` Andrew Morton [this message]
2022-03-23 23:07 ` [patch 37/41] panic: move panic_print before kmsg dumpers Andrew Morton
2022-03-23 23:07 ` [patch 38/41] kcov: split ioctl handling into locked and unlocked parts Andrew Morton
2022-03-23 23:07 ` [patch 39/41] kcov: properly handle subsequent mmap calls Andrew Morton
2022-03-23 23:07 ` [patch 40/41] kernel/resource: fix kfree() of bootmem memory again Andrew Morton
2022-03-23 23:07 ` [patch 41/41] Revert "ubsan, kcsan: Don't combine sanitizer with kcov on clang" Andrew Morton
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