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authorTejun Heo <tj@kernel.org>2018-01-22 23:00:55 +0100
committerIngo Molnar <mingo@kernel.org>2018-01-24 10:00:09 +0100
commit88f1c87de11a86d839f4ce5313e552d96709b990 (patch)
tree4869d6b64b9317c2eaf4df912b3dd6deec207fa4
parentfutex: Fix OWNER_DEAD fixup (diff)
downloadlinux-88f1c87de11a86d839f4ce5313e552d96709b990.tar.xz
linux-88f1c87de11a86d839f4ce5313e552d96709b990.zip
locking/lockdep: Avoid triggering hardlockup from debug_show_all_locks()
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> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kernel-team@fb.com Link: http://lkml.kernel.org/r/20180122220055.GB1771050@devbig577.frc2.facebook.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--kernel/locking/lockdep.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 5fa1324a4f29..521659044719 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 @@ retry:
if (!unlock)
if (read_trylock(&tasklist_lock))
unlock = 1;
+ touch_nmi_watchdog();
} while_each_thread(g, p);
pr_warn("\n");