From 55537871ef666b4153fd1ef8782e4a13fee142cc Mon Sep 17 00:00:00 2001 From: Jiri Kosina Date: Thu, 5 Nov 2015 18:44:41 -0800 Subject: kernel/watchdog.c: perform all-CPU backtrace in case of hard lockup In many cases of hardlockup reports, it's actually not possible to know why it triggered, because the CPU that got stuck is usually waiting on a resource (with IRQs disabled) in posession of some other CPU is holding. IOW, we are often looking at the stacktrace of the victim and not the actual offender. Introduce sysctl / cmdline parameter that makes it possible to have hardlockup detector perform all-CPU backtrace. Signed-off-by: Jiri Kosina Reviewed-by: Aaron Tomlin Cc: Ulrich Obergfell Acked-by: Don Zickus Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/sysctl/kernel.txt | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'Documentation/sysctl') diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt index 6fccb69c03e7..af70d1541d3a 100644 --- a/Documentation/sysctl/kernel.txt +++ b/Documentation/sysctl/kernel.txt @@ -33,6 +33,7 @@ show up in /proc/sys/kernel: - domainname - hostname - hotplug +- hardlockup_all_cpu_backtrace - hung_task_panic - hung_task_check_count - hung_task_timeout_secs @@ -292,6 +293,17 @@ Information Service) or YP (Yellow Pages) domainname. These two domain names are in general different. For a detailed discussion see the hostname(1) man page. +============================================================== +hardlockup_all_cpu_backtrace: + +This value controls the hard lockup detector behavior when a hard +lockup condition is detected as to whether or not to gather further +debug information. If enabled, arch-specific all-CPU stack dumping +will be initiated. + +0: do nothing. This is the default behavior. + +1: on detection capture more debug information. ============================================================== hotplug: -- cgit v1.2.3-58-ga151