From b3acc56bfe1287c6b666e80edc70b89eea2a1a80 Mon Sep 17 00:00:00 2001 From: Petr Tesarik Date: Mon, 23 Jun 2014 13:22:03 -0700 Subject: kexec: save PG_head_mask in VMCOREINFO To allow filtering of huge pages, makedumpfile must be able to identify them in the dump. This can be done by checking the appropriate page flag, so communicate its value to makedumpfile through the VMCOREINFO interface. There's only one small catch. Depending on how many page flags are available on a given architecture, this bit can be called PG_head or PG_compound. I sent a similar patch back in 2012, but Eric Biederman did not like using an #ifdef. So, this time I'm adding a common symbol (PG_head_mask) instead. See https://lkml.org/lkml/2012/11/28/91 for the previous version. Signed-off-by: Petr Tesarik Acked-by: Vivek Goyal Cc: Eric Biederman Cc: Paul Mackerras Cc: Fengguang Wu Cc: Benjamin Herrenschmidt Cc: Shaohua Li Cc: Alexey Kardashevskiy Cc: Sasha Levin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/page-flags.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include') diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 3c545b48aeab..8304959ad336 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -360,6 +360,9 @@ static inline void ClearPageCompound(struct page *page) ClearPageHead(page); } #endif + +#define PG_head_mask ((1L << PG_head)) + #else /* * Reduce page flag use as much as possible by overlapping -- cgit v1.2.3 From f3aca3d09525f87731ba6b892c9b010570bc54b4 Mon Sep 17 00:00:00 2001 From: Aaron Tomlin Date: Mon, 23 Jun 2014 13:22:05 -0700 Subject: nmi: provide the option to issue an NMI back trace to every cpu but current Sometimes it is preferred not to use the trigger_all_cpu_backtrace() routine when one wants to avoid capturing a back trace for current. For instance if one was previously captured recently. This patch provides a new routine namely trigger_allbutself_cpu_backtrace() which offers the flexibility to issue an NMI to every cpu but current and capture a back trace accordingly. Patch x86 and sparc to support new routine. [dzickus@redhat.com: add stub in #else clause] [dzickus@redhat.com: don't print message in single processor case, wrap with get/put_cpu based on Oleg's suggestion] [sfr@canb.auug.org.au: undo C99ism] Signed-off-by: Aaron Tomlin Signed-off-by: Don Zickus Acked-by: David S. Miller Cc: Mateusz Guzik Cc: Oleg Nesterov Signed-off-by: Stephen Rothwell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/nmi.h | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/nmi.h b/include/linux/nmi.h index 6a45fb583ff1..a17ab6398d7c 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -32,15 +32,24 @@ static inline void touch_nmi_watchdog(void) #ifdef arch_trigger_all_cpu_backtrace static inline bool trigger_all_cpu_backtrace(void) { - arch_trigger_all_cpu_backtrace(); + arch_trigger_all_cpu_backtrace(true); return true; } +static inline bool trigger_allbutself_cpu_backtrace(void) +{ + arch_trigger_all_cpu_backtrace(false); + return true; +} #else static inline bool trigger_all_cpu_backtrace(void) { return false; } +static inline bool trigger_allbutself_cpu_backtrace(void) +{ + return false; +} #endif #ifdef CONFIG_LOCKUP_DETECTOR -- cgit v1.2.3 From ed235875e2ca983197831337a986f0517074e1a0 Mon Sep 17 00:00:00 2001 From: Aaron Tomlin Date: Mon, 23 Jun 2014 13:22:05 -0700 Subject: kernel/watchdog.c: print traces for all cpus on lockup detection A 'softlockup' is defined as a bug that causes the kernel to loop in kernel mode for more than a predefined period to time, without giving other tasks a chance to run. Currently, upon detection of this condition by the per-cpu watchdog task, debug information (including a stack trace) is sent to the system log. On some occasions, we have observed that the "victim" rather than the actual "culprit" (i.e. the owner/holder of the contended resource) is reported to the user. Often this information has proven to be insufficient to assist debugging efforts. To avoid loss of useful debug information, for architectures which support NMI, this patch makes it possible to improve soft lockup reporting. This is accomplished by issuing an NMI to each cpu to obtain a stack trace. If NMI is not supported we just revert back to the old method. A sysctl and boot-time parameter is available to toggle this feature. [dzickus@redhat.com: add CONFIG_SMP in certain areas] [akpm@linux-foundation.org: additional CONFIG_SMP=n optimisations] [mq@suse.cz: fix warning] Signed-off-by: Aaron Tomlin Signed-off-by: Don Zickus Cc: David S. Miller Cc: Mateusz Guzik Cc: Oleg Nesterov Signed-off-by: Jan Moskyto Matejka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/nmi.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/linux/nmi.h b/include/linux/nmi.h index a17ab6398d7c..447775ee2c4b 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -57,6 +57,7 @@ int hw_nmi_is_cpu_stuck(struct pt_regs *); u64 hw_nmi_get_sample_period(int watchdog_thresh); extern int watchdog_user_enabled; extern int watchdog_thresh; +extern int sysctl_softlockup_all_cpu_backtrace; struct ctl_table; extern int proc_dowatchdog(struct ctl_table *, int , void __user *, size_t *, loff_t *); -- cgit v1.2.3