Merge branch 'akpm' (patches from Andrew)

Merge more updates from Andrew Morton:
 "Various misc subsystems, before getting into the post-linux-next
  material.

  41 patches.

  Subsystems affected by this patch series: procfs, misc, core-kernel,
  lib, checkpatch, init, pipe, minix, fat, cgroups, kexec, kdump,
  taskstats, panic, kcov, resource, and ubsan"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (41 commits)
  Revert "ubsan, kcsan: Don't combine sanitizer with kcov on clang"
  kernel/resource: fix kfree() of bootmem memory again
  kcov: properly handle subsequent mmap calls
  kcov: split ioctl handling into locked and unlocked parts
  panic: move panic_print before kmsg dumpers
  panic: add option to dump all CPUs backtraces in panic_print
  docs: sysctl/kernel: add missing bit to panic_print
  taskstats: remove unneeded dead assignment
  kasan: no need to unset panic_on_warn in end_report()
  ubsan: no need to unset panic_on_warn in ubsan_epilogue()
  panic: unset panic_on_warn inside panic()
  docs: kdump: add scp example to write out the dump file
  docs: kdump: update description about sysfs file system support
  arm64: mm: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef
  x86/setup: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef
  riscv: mm: init: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef
  kexec: make crashk_res, crashk_low_res and crash_notes symbols always visible
  cgroup: use irqsave in cgroup_rstat_flush_locked().
  fat: use pointer to simple type in put_user()
  minix: fix bug when opening a file with O_DIRECT
  ...

1 files changed, 24 insertions, 13 deletions

diff --git a/kernel/panic.c b/kernel/panic.c
index 55b50e052ec3..eb4dfb932c85 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);
@@ -147,10 +148,16 @@ void nmi_panic(struct pt_regs *regs, const char *msg)
 }
 EXPORT_SYMBOL(nmi_panic);
 
-static void panic_print_sys_info(void)
+static void panic_print_sys_info(bool console_flush)
 {
-	if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
-		console_flush_on_panic(CONSOLE_REPLAY_ALL);
+	if (console_flush) {
+		if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
+			console_flush_on_panic(CONSOLE_REPLAY_ALL);
+		return;
+	}
+
+	if (panic_print & PANIC_PRINT_ALL_CPU_BT)
+		trigger_all_cpu_backtrace();
 
 	if (panic_print & PANIC_PRINT_TASK_INFO)
 		show_state();
@@ -185,6 +192,16 @@ void panic(const char *fmt, ...)
 	int old_cpu, this_cpu;
 	bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
 
+	if (panic_on_warn) {
+		/*
+		 * This thread may hit another WARN() in the panic path.
+		 * Resetting this prevents additional WARN() from panicking the
+		 * system on this thread.  Other threads are blocked by the
+		 * panic_mutex in panic().
+		 */
+		panic_on_warn = 0;
+	}
+
 	/*
 	 * Disable local interrupts. This will prevent panic_smp_self_stop
 	 * from deadlocking the first cpu that invokes the panic, since
@@ -272,6 +289,8 @@ void panic(const char *fmt, ...)
 	 */
 	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
 
+	panic_print_sys_info(false);
+
 	kmsg_dump(KMSG_DUMP_PANIC);
 
 	/*
@@ -302,7 +321,7 @@ void panic(const char *fmt, ...)
 	debug_locks_off();
 	console_flush_on_panic(CONSOLE_FLUSH_PENDING);
 
-	panic_print_sys_info();
+	panic_print_sys_info(true);
 
 	if (!panic_blink)
 		panic_blink = no_blink;
@@ -576,16 +595,8 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
 	if (regs)
 		show_regs(regs);
 
-	if (panic_on_warn) {
-		/*
-		 * This thread may hit another WARN() in the panic path.
-		 * Resetting this prevents additional WARN() from panicking the
-		 * system on this thread.  Other threads are blocked by the
-		 * panic_mutex in panic().
-		 */
-		panic_on_warn = 0;
+	if (panic_on_warn)
 		panic("panic_on_warn set ...\n");
-	}
 
 	if (!regs)
 		dump_stack();