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From:   Daniel Vetter <daniel.vetter@ffwll.ch>
To:     Intel Graphics Development <intel-gfx@lists.freedesktop.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        Daniel Vetter <daniel.vetter@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
        Dmitry Vyukov <dvyukov@google.com>,
        "Paul E. McKenney" <paulmck@linux.ibm.com>,
        Valdis Kletnieks <valdis.kletnieks@vt.edu>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        "Liu, Chuansheng" <chuansheng.liu@intel.com>
Subject: [PATCH] RFC: hung_task: taint kernel
Date:   Thu,  2 May 2019 22:46:48 +0200
Message-Id: <20190502204648.5537-1-daniel.vetter@ffwll.ch>
In-Reply-To: <20190502194208.3535-1-daniel.vetter@ffwll.ch>
References: <20190502194208.3535-1-daniel.vetter@ffwll.ch>
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There's the hung_task_panic sysctl, but that's a bit an extreme measure.
As a fallback taint at least the machine.

Our CI uses this to decide when a reboot is necessary, plus to figure
out whether the kernel is still happy.

v2: Works much better when I put the else { add_taint() } at the right
place.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>
Cc: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: "Liu, Chuansheng" <chuansheng.liu@intel.com>
---
 kernel/hung_task.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index f108a95882c6..d90d98f53ccb 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -117,6 +117,8 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
 		console_verbose();
 		hung_task_show_lock = true;
 		hung_task_call_panic = true;
+	} else {
+		add_taint(TAINT_WARN, LOCKDEP_STILL_OK);
 	}
 
 	/*
-- 
2.20.1