From: john.hubbard@gmail•com
To: Andrew Morton <akpm@linux-foundation•org>
Cc: Stephen Rothwell <sfr@canb•auug.org.au>,
linux-next@vger•kernel.org, mm-commits@vger•kernel.org,
John Hubbard <jhubbard@nvidia•com>
Subject: [PATCH v3] watchdog: Fix a watchdog crash in some configurations
Date: Tue, 5 May 2015 13:20:45 -0700 [thread overview]
Message-ID: <1430857245-16927-1-git-send-email-jhubbard@nvidia.com> (raw)
In-Reply-To: <55491ef8.oLKEdMAPkQJVpO38%akpm@linux-foundation.org>
From: John Hubbard <jhubbard@nvidia•com>
Commit <8fcf2cc768acd845c> in linux-next
introduced a regression in some configurations. Specifically,
with CONFIG_NO_HZ_FULL set, and CONFIG_NO_HZ_FULL_ALL *not* set,
the kernel will crash in lockup_detector_init(), due to a
NULL tick_nohz_full_mask pointer.
This is because the above commit uses tick_nohz_full_mask
(in lockup_detector_init), if CONFIG_NO_HZ_FULL is set, but
tick_nohz_full_mask only gets allocated if either:
a) CONFIG_NO_HZ_FULL_ALL is set, or
b) Someone passes in nohz_full=<any_value> on the boot
args line.
To correct this, change lockup_detector_init so that it does
a runtime check instead of the ifdef check. This fix is
simpler than my original proposed fix, thanks to Chris Metcalf
for that.
Signed-off-by: John Hubbard <jhubbard@nvidia•com>
---
kernel/watchdog.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/kernel/watchdog.c b/kernel/watchdog.c
index 40fda2f..e8caf09 100644
--- a/kernel/watchdog.c
+++ b/kernel/watchdog.c
@@ -920,14 +920,13 @@ void __init lockup_detector_init(void)
{
set_sample_period();
-#ifdef CONFIG_NO_HZ_FULL
- if (!cpumask_empty(tick_nohz_full_mask))
- pr_info("Disabling watchdog on nohz_full cores by default\n");
- cpumask_andnot(&watchdog_cpumask, cpu_possible_mask,
- tick_nohz_full_mask);
-#else
- cpumask_copy(&watchdog_cpumask, cpu_possible_mask);
-#endif
+ if (tick_nohz_full_enabled()) {
+ if (!cpumask_empty(tick_nohz_full_mask))
+ pr_info("Disabling watchdog on nohz_full cores by default\n");
+ cpumask_andnot(&watchdog_cpumask, cpu_possible_mask,
+ tick_nohz_full_mask);
+ } else
+ cpumask_copy(&watchdog_cpumask, cpu_possible_mask);
if (watchdog_enabled)
watchdog_enable_all_cpus();
--
2.3.7
next parent reply other threads:[~2015-05-05 20:21 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <55491ef8.oLKEdMAPkQJVpO38%akpm@linux-foundation.org>
2015-05-05 20:20 ` john.hubbard [this message]
2015-05-05 20:42 ` [PATCH v3] watchdog: Fix a watchdog crash in some configurations John Hubbard
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