2 files changed, 29 insertions, 2 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 9973a7e2e0ac..b9f67781c577 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2361,6 +2361,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         timeout < 0: reboot immediately
                         Format: <timeout>
 
+        crash_kexec_post_notifiers
+                        Run kdump after running panic-notifiers and dumping
+                        kmsg. This only for the users who doubt kdump always
+                        succeeds in any situation.
+                        Note that this also increases risks of kdump failure,
+                        because some panic notifiers can make the crashed
+                        kernel more unstable.
+
         parkbd.port=    [HW] Parallel port number the keyboard adapter is
                         connected to, default is 0.
                         Format: <parport#>
diff --git a/kernel/panic.c b/kernel/panic.c
index d02fa9fef46a..62e16cef9cc2 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -32,6 +32,7 @@ static unsigned long tainted_mask;
 static int pause_on_oops;
 static int pause_on_oops_flag;
 static DEFINE_SPINLOCK(pause_on_oops_lock);
+static bool crash_kexec_post_notifiers;
 
 int panic_timeout = CONFIG_PANIC_TIMEOUT;
 EXPORT_SYMBOL_GPL(panic_timeout);
@@ -112,9 +113,11 @@ void panic(const char *fmt, ...)
         /*
          * If we have crashed and we have a crash kernel loaded let it handle
          * everything else.
-         * Do we want to call this before we try to display a message?
+         * If we want to run this after calling panic_notifiers, pass
+         * the "crash_kexec_post_notifiers" option to the kernel.
          */
-        crash_kexec(NULL);
+        if (!crash_kexec_post_notifiers)
+                crash_kexec(NULL);
 
         /*
          * Note smp_send_stop is the usual smp shutdown function, which
@@ -131,6 +134,15 @@ void panic(const char *fmt, ...)
 
         kmsg_dump(KMSG_DUMP_PANIC);
 
+        /*
+         * If you doubt kdump always works fine in any situation,
+         * "crash_kexec_post_notifiers" offers you a chance to run
+         * panic_notifiers and dumping kmsg before kdump.
+         * Note: since some panic_notifiers can make crashed kernel
+         * more unstable, it can increase risks of the kdump failure too.
+         */
+        crash_kexec(NULL);
+
         bust_spinlocks(0);
 
         if (!panic_blink)
@@ -472,6 +484,13 @@ EXPORT_SYMBOL(__stack_chk_fail);
 core_param(panic, panic_timeout, int, 0644);
 core_param(pause_on_oops, pause_on_oops, int, 0644);
 
+static int __init setup_crash_kexec_post_notifiers(char *s)
+{
+        crash_kexec_post_notifiers = true;
+        return 0;
+}
+early_param("crash_kexec_post_notifiers", setup_crash_kexec_post_notifiers);
+
 static int __init oops_setup(char *s)
 {
         if (!s)