[merged mm-nonmm-stable] watchdog-hardlockup-avoid-large-stack-frames-in-watchdog_hardlockup_check.patch removed from -mm tree

[merged mm-nonmm-stable] watchdog-hardlockup-avoid-large-stack-frames-in-watchdog_hardlockup_check.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: watchdog/hardlockup: avoid large stack frames in watchdog_hardlockup_check()
has been removed from the -mm tree.  Its filename was
     watchdog-hardlockup-avoid-large-stack-frames-in-watchdog_hardlockup_check.patch

This patch was dropped because it was merged into the mm-nonmm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Douglas Anderson <dianders@chromium.org>
Subject: watchdog/hardlockup: avoid large stack frames in watchdog_hardlockup_check()
Date: Fri, 4 Aug 2023 07:00:43 -0700

After commit 77c12fc95980 ("watchdog/hardlockup: add a "cpu" param to
watchdog_hardlockup_check()") we started storing a `struct cpumask` on the
stack in watchdog_hardlockup_check().  On systems with CONFIG_NR_CPUS set
to 8192 this takes up 1K on the stack.  That triggers warnings with
`CONFIG_FRAME_WARN` set to 1024.

We'll use the new trigger_allbutcpu_cpu_backtrace() to avoid needing to
use a CPU mask at all.

Link: https://lkml.kernel.org/r/20230804065935.v4.2.I501ab68cb926ee33a7c87e063d207abf09b9943c@changeid
Fixes: 77c12fc95980 ("watchdog/hardlockup: add a "cpu" param to watchdog_hardlockup_check()")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/r/202307310955.pLZDhpnl-lkp@intel.com
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/watchdog.c |    9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

--- a/kernel/watchdog.c~watchdog-hardlockup-avoid-large-stack-frames-in-watchdog_hardlockup_check
+++ a/kernel/watchdog.c
@@ -151,9 +151,6 @@ void watchdog_hardlockup_check(unsigned
 	 */
 	if (is_hardlockup(cpu)) {
 		unsigned int this_cpu = smp_processor_id();
-		struct cpumask backtrace_mask;
-
-		cpumask_copy(&backtrace_mask, cpu_online_mask);
 
 		/* Only print hardlockups once. */
 		if (per_cpu(watchdog_hardlockup_warned, cpu))
@@ -167,10 +164,8 @@ void watchdog_hardlockup_check(unsigned
 				show_regs(regs);
 			else
 				dump_stack();
-			cpumask_clear_cpu(cpu, &backtrace_mask);
 		} else {
-			if (trigger_single_cpu_backtrace(cpu))
-				cpumask_clear_cpu(cpu, &backtrace_mask);
+			trigger_single_cpu_backtrace(cpu);
 		}
 
 		/*
@@ -179,7 +174,7 @@ void watchdog_hardlockup_check(unsigned
 		 */
 		if (sysctl_hardlockup_all_cpu_backtrace &&
 		    !test_and_set_bit(0, &watchdog_hardlockup_all_cpu_dumped))
-			trigger_cpumask_backtrace(&backtrace_mask);
+			trigger_allbutcpu_cpu_backtrace(cpu);
 
 		if (hardlockup_panic)
 			nmi_panic(regs, "Hard LOCKUP");
_

Patches currently in -mm which might be from dianders@chromium.org are