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| author | Guilherme G. Piccoli <gpiccoli@igalia.com> | 2022-03-23 16:07:06 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-03-23 19:00:35 -0700 |
| commit | 8d470a45d1a65e6a308aeee5da7f5b37d3303c04 (patch) | |
| tree | 868c5db3a56bc8636621215a20ac3b310cb0f611 | |
| parent | a1ff1de00db21ecb956213f046b79741b64c6b65 (diff) | |
| download | ci-8d470a45d1a65e6a308aeee5da7f5b37d3303c04.tar.gz | |
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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 1 | ||||
| -rw-r--r-- | Documentation/admin-guide/sysctl/kernel.rst | 1 | ||||
| -rw-r--r-- | kernel/panic.c | 4 |
3 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 7123524a86b8b4..6287f6be4a98d3 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/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] diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 0f86e9f9312934..cfd6c20ce42e57 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -796,6 +796,7 @@ 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:: diff --git a/kernel/panic.c b/kernel/panic.c index 95ba825522dd4e..3c3fb36d8d4144 100644 --- a/kernel/panic.c +++ b/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(); |