diff options
| author | Ryo Takakura <takakura@valinux.co.jp> | 2024-08-12 16:27:03 +0900 |
|---|---|---|
| committer | Petr Mladek <pmladek@suse.com> | 2024-08-13 14:16:22 +0200 |
| commit | bcc954c6caba01fca143162d5fbb90e46aa1ad80 (patch) | |
| tree | 1753c205754918fdb84a270566df359ae6dc8cd5 | |
| parent | 8bf100092d60bf586bbc1a3a2cd833bb212d9d53 (diff) | |
printk/panic: Allow cpu backtraces to be written into ringbuffer during panic
commit 779dbc2e78d7 ("printk: Avoid non-panic CPUs writing
to ringbuffer") disabled non-panic CPUs to further write messages to
ringbuffer after panicked.
Since the commit, non-panicked CPU's are not allowed to write to
ring buffer after panicked and CPU backtrace which is triggered
after panicked to sample non-panicked CPUs' backtrace no longer
serves its function as it has nothing to print.
Fix the issue by allowing non-panicked CPUs to write into ringbuffer
while CPU backtrace is in flight.
Fixes: 779dbc2e78d7 ("printk: Avoid non-panic CPUs writing to ringbuffer")
Signed-off-by: Ryo Takakura <takakura@valinux.co.jp>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240812072703.339690-1-takakura@valinux.co.jp
Signed-off-by: Petr Mladek <pmladek@suse.com>
| -rw-r--r-- | include/linux/panic.h | 1 | ||||
| -rw-r--r-- | kernel/panic.c | 8 | ||||
| -rw-r--r-- | kernel/printk/printk.c | 2 |
3 files changed, 9 insertions, 2 deletions
diff --git a/include/linux/panic.h b/include/linux/panic.h index 3130e0b5116b..54d90b6c5f47 100644 --- a/include/linux/panic.h +++ b/include/linux/panic.h @@ -16,6 +16,7 @@ extern void oops_enter(void); extern void oops_exit(void); extern bool oops_may_print(void); +extern bool panic_triggering_all_cpu_backtrace; extern int panic_timeout; extern unsigned long panic_print; extern int panic_on_oops; diff --git a/kernel/panic.c b/kernel/panic.c index f861bedc1925..2a0449144f82 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -64,6 +64,8 @@ unsigned long panic_on_taint; bool panic_on_taint_nousertaint = false; static unsigned int warn_limit __read_mostly; +bool panic_triggering_all_cpu_backtrace; + int panic_timeout = CONFIG_PANIC_TIMEOUT; EXPORT_SYMBOL_GPL(panic_timeout); @@ -253,8 +255,12 @@ void check_panic_on_warn(const char *origin) */ static void panic_other_cpus_shutdown(bool crash_kexec) { - if (panic_print & PANIC_PRINT_ALL_CPU_BT) + if (panic_print & PANIC_PRINT_ALL_CPU_BT) { + /* Temporary allow non-panic CPUs to write their backtraces. */ + panic_triggering_all_cpu_backtrace = true; trigger_all_cpu_backtrace(); + panic_triggering_all_cpu_backtrace = false; + } /* * Note that smp_send_stop() is the usual SMP shutdown function, diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 054c0e7784fd..c22b07049c38 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2316,7 +2316,7 @@ asmlinkage int vprintk_emit(int facility, int level, * non-panic CPUs are generating any messages, they will be * silently dropped. */ - if (other_cpu_in_panic()) + if (other_cpu_in_panic() && !panic_triggering_all_cpu_backtrace) return 0; if (level == LOGLEVEL_SCHED) { |