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authorchenqiwu <chenqiwu@xiaomi.com>2019-12-19 14:29:53 +0800
committerChristian Brauner <christian.brauner@ubuntu.com>2019-12-21 16:48:01 +0100
commit43cf75d96409a20ef06b756877a2e72b10a026fc (patch)
treee4ee7ca8f43d13a2ba8348a314ec23883b8b9a70 /kernel
parent0b8d616fb5a8ffa307b1d3af37f55c15dae14f28 (diff)
exit: panic before exit_mm() on global init exit
Currently, when global init and all threads in its thread-group have exited we panic via: do_exit() -> exit_notify() -> forget_original_parent() -> find_child_reaper() This makes it hard to extract a useable coredump for global init from a kernel crashdump because by the time we panic exit_mm() will have already released global init's mm. This patch moves the panic futher up before exit_mm() is called. As was the case previously, we only panic when global init and all its threads in the thread-group have exited. Signed-off-by: chenqiwu <chenqiwu@xiaomi.com> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Acked-by: Oleg Nesterov <oleg@redhat.com> [christian.brauner@ubuntu.com: fix typo, rewrite commit message] Link: https://lore.kernel.org/r/1576736993-10121-1-git-send-email-qiwuchen55@gmail.com Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/exit.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/kernel/exit.c b/kernel/exit.c
index a46a50d67002..fc364272759d 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -517,10 +517,6 @@ static struct task_struct *find_child_reaper(struct task_struct *father,
}
write_unlock_irq(&tasklist_lock);
- if (unlikely(pid_ns == &init_pid_ns)) {
- panic("Attempted to kill init! exitcode=0x%08x\n",
- father->signal->group_exit_code ?: father->exit_code);
- }
list_for_each_entry_safe(p, n, dead, ptrace_entry) {
list_del_init(&p->ptrace_entry);
@@ -786,6 +782,14 @@ void __noreturn do_exit(long code)
acct_update_integrals(tsk);
group_dead = atomic_dec_and_test(&tsk->signal->live);
if (group_dead) {
+ /*
+ * If the last thread of global init has exited, panic
+ * immediately to get a useable coredump.
+ */
+ if (unlikely(is_global_init(tsk)))
+ panic("Attempted to kill init! exitcode=0x%08x\n",
+ tsk->signal->group_exit_code ?: (int)code);
+
#ifdef CONFIG_POSIX_TIMERS
hrtimer_cancel(&tsk->signal->real_timer);
exit_itimers(tsk->signal);

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