From: Tejun Heo <tj@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: [PATCH] lockdep: Avoid triggering hardlockup from debug_show_all_locks()
Date: Mon, 22 Jan 2018 14:00:55 -0800 [thread overview]
Message-ID: <20180122220055.GB1771050@devbig577.frc2.facebook.com> (raw)
debug_show_all_locks() iterates all tasks and print held locks whole
holding tasklist_lock. This can take a while on a slow console device
and may end up triggering NMI hardlockup detector if someone else ends
up waiting for tasklist_lock.
Touch the NMI watchdog while printing the held locks to avoid
spuriously triggering the hardlockup detector.
Signed-off-by: Tejun Heo <tj@kernel.org>
---
kernel/locking/lockdep.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 5fa1324..5216590 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -49,6 +49,7 @@
#include <linux/gfp.h>
#include <linux/random.h>
#include <linux/jhash.h>
+#include <linux/nmi.h>
#include <asm/sections.h>
@@ -4490,6 +4491,7 @@ void debug_show_all_locks(void)
if (!unlock)
if (read_trylock(&tasklist_lock))
unlock = 1;
+ touch_nmi_watchdog();
} while_each_thread(g, p);
pr_warn("\n");
next reply other threads:[~2018-01-22 22:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-22 22:00 Tejun Heo [this message]
2018-01-23 19:03 ` [PATCH] lockdep: Avoid triggering hardlockup from debug_show_all_locks() Rik van Riel
2018-01-23 20:57 ` Tejun Heo
2018-01-23 21:00 ` Steven Rostedt
2018-01-23 21:11 ` Tejun Heo
2018-01-24 2:49 ` Sergey Senozhatsky
2018-01-24 2:54 ` Steven Rostedt
2018-01-24 5:00 ` Sergey Senozhatsky
2018-01-24 19:10 ` Tejun Heo
2018-01-24 10:38 ` [tip:locking/urgent] locking/lockdep: " tip-bot for Tejun Heo
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