linux-kernel - [PATCH 1/1] hung_task: fix objtool sibling call warning in watchdog()

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Message-ID: <20250731023934.48840-1-lance.yang@linux.dev>
Date: Thu, 31 Jul 2025 10:39:34 +0800
From: Lance Yang <lance.yang@...ux.dev>
To: lkp@...el.com,
	akpm@...ux-foundation.org
Cc: zi.li@...ux.dev,
	llvm@...ts.linux.dev,
	mhiramat@...nel.org,
	oe-kbuild-all@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Lance Yang <lance.yang@...ux.dev>
Subject: [PATCH 1/1] hung_task: fix objtool sibling call warning in watchdog()

From: Lance Yang <lance.yang@...ux.dev>

The kernel test robot reported an objtool warning on the loongarch
architecture with clang:

        vmlinux.o: warning: objtool: watchdog+0x418: sibling call from
callable instruction with modified stack frame

To resolve this, explicitly prevent the compiler from inlining or
performing a tail call on check_hung_uninterruptible_tasks() by marking
it with the noinline attribute. This ensures a standard function call
with a proper stack frame, satisfying objtool's validation requirements.

Reported-by: kernel test robot <lkp@...el.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202507301256.cZlxQ10s-lkp@intel.com/
Signed-off-by: Lance Yang <lance.yang@...ux.dev>
---
 kernel/hung_task.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 8708a1205f82..a5b5a0a2c262 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -283,7 +283,7 @@ static bool rcu_lock_break(struct task_struct *g, struct task_struct *t)
  * a really long time (120 seconds). If that happens, print out
  * a warning.
  */
-static void check_hung_uninterruptible_tasks(unsigned long timeout)
+static noinline void check_hung_uninterruptible_tasks(unsigned long timeout)
 {
 	int max_count = sysctl_hung_task_check_count;
 	unsigned long last_break = jiffies;
-- 
2.49.0