Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
From:   Tiezhu Yang <yangtiezhu@loongson.cn>
To:     Baoquan He <bhe@redhat.com>, Jonathan Corbet <corbet@lwn.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Marco Elver <elver@google.com>
Cc:     kexec@lists.infradead.org, linux-doc@vger.kernel.org,
        kasan-dev@googlegroups.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH 4/5] sched: unset panic_on_warn before calling panic()
Date:   Fri, 28 Jan 2022 19:42:24 +0800
Message-Id: <1643370145-26831-5-git-send-email-yangtiezhu@loongson.cn>
In-Reply-To: <1643370145-26831-1-git-send-email-yangtiezhu@loongson.cn>
References: <1643370145-26831-1-git-send-email-yangtiezhu@loongson.cn>
Precedence: bulk

As done in the full WARN() handler, panic_on_warn needs to be cleared
before calling panic() to avoid recursive panics.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 kernel/sched/core.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 848eaa0..f5b0886 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5524,8 +5524,17 @@ static noinline void __schedule_bug(struct task_struct *prev)
 		pr_err("Preemption disabled at:");
 		print_ip_sym(KERN_ERR, preempt_disable_ip);
 	}
-	if (panic_on_warn)
+
+	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;
 		panic("scheduling while atomic\n");
+	}
 
 	dump_stack();
 	add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
-- 
2.1.0