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watchdog: handle the ENODEV failure case of lockup_detector_delay_init() separately

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When watchdog_hardlockup_probe() is being called by
lockup_detector_delay_init(), an error return of -ENODEV will happen
for the arm64 arch when arch_perf_nmi_is_available() returns false. This
means that NMI is not usable by the hard lockup detector and so has to
be disabled. This can be considered a deficiency in that particular
arm64 chip, but there is nothing we can do about it.  That also means
the following error will always be reported when the kernel boot up.

  watchdog: Delayed init of the lockup detector failed: -19

The word "failed" itself has a connotation that there is something
wrong with the kernel which is not really the case here. Handle this
special ENODEV case separately and explain the reason behind disabling
hard lockup detector without causing anxiety for those users who read
the above message and wonder about it.

Link: https://lkml.kernel.org/r/20240802151621.617244-1-longman@redhat.com
Signed-off-by: Waiman Long <longman@redhat.com>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Joel Granados <j.granados@samsung.com>
Cc: Li Zhe <lizhe.67@bytedance.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Waiman Long 2024-08-02 11:16:21 -04:00 committed by Andrew Morton
parent e0ba72e3a4
commit 97cf8f5f93
1 changed files with 4 additions and 1 deletions
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5
kernel/watchdog.c
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@ -1203,7 +1203,10 @@ static void __init lockup_detector_delay_init(struct work_struct *work)
ret = watchdog_hardlockup_probe();
if (ret) {
pr_info("Delayed init of the lockup detector failed: %d\n", ret);
if (ret == -ENODEV)
pr_info("NMI not fully supported\n");
else
pr_info("Delayed init of the lockup detector failed: %d\n", ret);
pr_info("Hard watchdog permanently disabled\n");
return;
}