Commit-ID: 115ef3b7e61ac64e32827611a127002672ed3725
Gitweb: http://git.kernel.org/tip/115ef3b7e61ac64e32827611a127002672ed3725
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Mon, 25 Sep 2017 20:21:54 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Mon, 25 Sep 2017 20:21:54 +0200
watchdog/hardlockup/perf: Cure UP damage
for_each_cpu() unintuitively reports CPU0 as set independend of the actual
cpumask content on UP kernels. That leads to a NULL pointer dereference
when the cleanup function is invoked and there is no event to clean up.
Reported-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
kernel/watchdog_hld.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c
index b293115..204a8ca 100644
--- a/kernel/watchdog_hld.c
+++ b/kernel/watchdog_hld.c
@@ -220,8 +220,13 @@ void hardlockup_detector_perf_cleanup(void)
for_each_cpu(cpu, &dead_events_mask) {
struct perf_event *event = per_cpu(watchdog_ev, cpu);
+ /*
+ * Required because for_each_cpu() reports unconditionally
+ * CPU0 as set on UP kernels. Sigh.
+ */
+ if (event)
+ perf_event_release_kernel(event);
per_cpu(watchdog_ev, cpu) = NULL;
- perf_event_release_kernel(event);
}
cpumask_clear(&dead_events_mask);
}
--
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