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* softlock: fix false panic which can occur if softlockup_thresh is reducedMandeep Singh Baines2009-01-14
| | | | | | | | | | | | | At run-time, if softlockup_thresh is changed to a much lower value, touch_timestamp is likely to be much older than the new softlock_thresh. This will cause a false softlockup to be detected. If softlockup_panic is enabled, the system will panic. The fix is to touch all watchdogs before changing softlockup_thresh. Signed-off-by: Mandeep Singh Baines <msb@google.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* cpumask: convert rest of files in kernel/Rusty Russell2008-12-31
| | | | | | | | | | | | | | | Impact: Reduce stack usage, use new cpumask API. Mainly changing cpumask_t to 'struct cpumask' and similar simple API conversion. Two conversions worth mentioning: 1) we use cpumask_any_but to avoid a temporary in kernel/softlockup.c, 2) Use cpumask_var_t in taskstats_user_cmd(). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Mike Travis <travis@sgi.com> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@redhat.com>
* cpumask: remove any_online_cpu() users: kernel/Rusty Russell2008-12-31
| | | | | | | | | | | | | | Impact: Remove obsolete API usage any_online_cpu() is a good name, but it takes a cpumask_t, not a pointer. There are several places where any_online_cpu() doesn't really want a mask arg at all. Replace all callers with cpumask_any() and cpumask_any_and(). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Mike Travis <travis@sgi.com>
* Merge commit 'v2.6.28' into core/coreIngo Molnar2008-12-25
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| * check_hung_task(): unsigned sysctl_hung_task_warnings cannot be less than 0Roel Kluin2008-12-03
| | | | | | | | | | | | | | | | | | Impact: fix warnings-limit cutoff check for debug feature unsigned sysctl_hung_task_warnings cannot be less than 0 Signed-off-by: Roel Kluin <roel.kluin@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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*-. \ Merge branches 'core/debug', 'core/futexes', 'core/locking', 'core/rcu', ↵Ingo Molnar2008-11-24
|\ \ \ | |_|/ |/| | | | | 'core/signal', 'core/urgent' and 'core/xen' into core/core
| * | Merge branch 'linus' into core/debugIngo Molnar2008-09-10
| |\| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Conflicts: lib/vsprintf.c Manual merge: include/linux/kernel.h Signed-off-by: Ingo Molnar <mingo@elte.hu>
| * | softlockup: increase hung tasks check from 2 minutes to 8 minutesIngo Molnar2008-09-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Andrew says: > Seems that about 100% of the reports we get of this warning triggering > are sys_sync, transaction commit, etc. increase the timeout. If it still triggers for people, we can kill it. Signed-off-by: Ingo Molnar <mingo@elte.hu>
* | | Make the taint flags reliableAndi Kleen2008-10-16
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It's somewhat unlikely that it happens, but right now a race window between interrupts or machine checks or oopses could corrupt the tainted bitmap because it is modified in a non atomic fashion. Convert the taint variable to an unsigned long and use only atomic bit operations on it. Unfortunately this means the intvec sysctl functions cannot be used on it anymore. It turned out the taint sysctl handler could actually be simplified a bit (since it only increases capabilities) so this patch actually removes code. [akpm@linux-foundation.org: remove unneeded include] Signed-off-by: Andi Kleen <ak@linux.intel.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | softlockup: minor cleanup, don't check task->state twiceOleg Nesterov2008-09-02
| | | | | | | | | | | | | | | | | | | | The recent commit 16d9679f33caf7e683471647d1472bfe133d858 changed check_hung_task() to filter out the TASK_KILLABLE tasks. We can move this check to the caller which has to test t->state anyway. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | Don't trigger softlockup detector on network fs blocked tasksAndi Kleen2008-08-29
|/ | | | | | | | | | | | | | | | | | | Pulling the ethernet cable on a 2.6.27-rc system with NFS mounts currently leads to an ongoing flood of soft lockup detector backtraces for all tasks blocked on the NFS mounts when the hickup takes longer than 120s. I don't think NFS problems should be all that noisy. Luckily there's a reasonably easy way to distingush this case. Don't report task softlockup warnings for tasks in TASK_KILLABLE state, which is used by the network file systems. I believe this patch is a 2.6.27 candidate. Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Full conversion to early_initcall() interface, remove old interfaceEduard - Gabriel Munteanu2008-07-26
| | | | | | | | | | | | | | | | A previous patch added the early_initcall(), to allow a cleaner hooking of pre-SMP initcalls. Now we remove the older interface, converting all existing users to the new one. [akpm@linux-foundation.org: cleanups] [akpm@linux-foundation.org: build fix] [kosaki.motohiro@jp.fujitsu.com: warning fix] [kosaki.motohiro@jp.fujitsu.com: warning fix] Signed-off-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro> Cc: Tom Zanussi <tzanussi@gmail.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* softlockup: fix watchdog task wakeup frequencyJohannes Weiner2008-07-01
| | | | | | | | | | | | | | The print_timestamp can never be bigger than the touch_timestamp, at maximum it can be equal. And if it is, the second check for touch_timestamp + 1 bigger print_timestamp is always true, too. The check for equality is sufficient as we proceed in one-second-steps and are at least one second away from the last print-out if we have another timestamp. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* softlockup: fix watchdog task wakeup frequencyJohannes Weiner2008-06-30
| | | | | | | | | | Updating the timestamp more often is pointless as we print the warnings only if we exceed the threshold. And the check for hung tasks relies on the last timestamp, so it will keep working correctly, too. Signed-off-by: Johannes Weiner <hannes@saeurebad.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* softlockup: show irqtraceVegard Nossum2008-06-25
| | | | | | | | | | | This patch adds some information about when interrupts were last enabled and disabled to the output of the softlockup detector. Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Johannes Weiner <hannes@saeurebad.de> Cc: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* softlockup: print a module list on being stuckArjan van de Ven2008-06-18
| | | | | | | | | | | Most places in the kernel that go BUG: print a module list (which is very useful for doing statistics and finding patterns), however the softlockup detector does not do this yet. This patch adds the one line change to fix this gap. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* softlockup: fix NMI hangs due to lock race - 2.6.26-rc regressionJason Wessel2008-06-02
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The touch_nmi_watchdog() routine on x86 ultimately calls touch_softlockup_watchdog(). The problem is that to touch the softlockup watchdog, the cpu_clock code has to be called which could involve multiple cpu locks and can lead to a hard hang if one of the locks is held by a processor that is not going to return anytime soon (such as could be the case with kgdb or perhaps even with some other kind of exception). This patch causes the public version of the touch_softlockup_watchdog() to defer the cpu clock access to a later point. The test case for this problem is to use the following kernel config options: CONFIG_KGDB_TESTS=y CONFIG_KGDB_TESTS_ON_BOOT=y CONFIG_KGDB_TESTS_BOOT_STRING="V1F100I100000" It should be noted that kgdb test suite and these options were not available until 2.6.26-rc2, so it was necessary to patch the kgdb test suite during the bisection. I would consider this patch a regression fix because the problem first appeared in commit 27ec4407790d075c325e1f4da0a19c56953cce23 when some logic was added to try to periodically sync the clocks. It was possible to work around this particular problem by simply not performing the sync anytime the system was in a critical context. This was ok until commit 3e51f33fcc7f55e6df25d15b55ed10c8b4da84cd, which added config option CONFIG_HAVE_UNSTABLE_SCHED_CLOCK and some multi-cpu locks to sync the clocks. It became clear that accessing this code from an nmi was the source of the lockups. Avoiding the access to the low level clock code from an code inside the NMI processing also fixed the problem with the 27ec44... commit. Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* softlockup: fix softlockup_thresh unaligned access and disable detection at ↵Dimitri Sivanich2008-05-25
| | | | | | | | | | | | | | | | | runtime Fix unaligned access errors when setting softlockup_thresh on 64 bit platforms. Allow softlockup detection to be disabled by setting softlockup_thresh <= 0. Detect that boot time softlockup detection has been disabled earlier in softlockup_tick. Signed-off-by: Dimitri Sivanich <sivanich@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* softlockup: allow panic on lockupIngo Molnar2008-05-25
| | | | | | | | | | | | | | | | | | | | allow users to configure the softlockup detector to generate a panic instead of a warning message. high-availability systems might opt for this strict method (combined with panic_timeout= boot option/sysctl), instead of generating softlockup warnings ad infinitum. also, automated tests work better if the system reboots reliably (into a safe kernel) in case of a lockup. The full spectrum of configurability is supported: boot option, sysctl option and Kconfig option. it's default-disabled. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* softlockup: fix task state settingDmitry Adamushko2008-02-29
| | | | | | | | kthread_stop() can be called when a 'watchdog' thread is executing after kthread_should_stop() but before set_task_state(TASK_INTERRUPTIBLE). Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* debug: softlockup looping fixPeter Zijlstra2008-02-01
| | | | | | | | | | | | | | | | | | | | | | | | Rafael J. Wysocki reported weird, multi-seconds delays during suspend/resume and bisected it back to: commit 82a1fcb90287052aabfa235e7ffc693ea003fe69 Author: Ingo Molnar <mingo@elte.hu> Date: Fri Jan 25 21:08:02 2008 +0100 softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks fix it: - restore the old wakeup mechanism - fix break usage in do_each_thread() { } while_each_thread(). - fix the hotplug switch stmt, a fall-through case was broken. Bisected-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* softlockup: fix signednessIngo Molnar2008-01-25
| | | | | | | | fix softlockup tunables signedness. mark tunables read-mostly. Signed-off-by: Ingo Molnar <mingo@elte.hu>
* softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasksIngo Molnar2008-01-25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | this patch extends the soft-lockup detector to automatically detect hung TASK_UNINTERRUPTIBLE tasks. Such hung tasks are printed the following way: ------------------> INFO: task prctl:3042 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message prctl D fd5e3793 0 3042 2997 f6050f38 00000046 00000001 fd5e3793 00000009 c06d8264 c06dae80 00000286 f6050f40 f6050f00 f7d34d90 f7d34fc8 c1e1be80 00000001 f6050000 00000000 f7e92d00 00000286 f6050f18 c0489d1a f6050f40 00006605 00000000 c0133a5b Call Trace: [<c04883a5>] schedule_timeout+0x6d/0x8b [<c04883d8>] schedule_timeout_uninterruptible+0x15/0x17 [<c0133a76>] msleep+0x10/0x16 [<c0138974>] sys_prctl+0x30/0x1e2 [<c0104c52>] sysenter_past_esp+0x5f/0xa5 ======================= 2 locks held by prctl/3042: #0: (&sb->s_type->i_mutex_key#5){--..}, at: [<c0197d11>] do_fsync+0x38/0x7a #1: (jbd_handle){--..}, at: [<c01ca3d2>] journal_start+0xc7/0xe9 <------------------ the current default timeout is 120 seconds. Such messages are printed up to 10 times per bootup. If the system has crashed already then the messages are not printed. if lockdep is enabled then all held locks are printed as well. this feature is a natural extension to the softlockup-detector (kernel locked up without scheduling) and to the NMI watchdog (kernel locked up with IRQs disabled). [ Gautham R Shenoy <ego@in.ibm.com>: CPU hotplug fixes. ] [ Andrew Morton <akpm@linux-foundation.org>: build warning fix. ] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
* Use helpers to obtain task pid in printksPavel Emelyanov2007-10-19
| | | | | | | | | | | | | | | | The task_struct->pid member is going to be deprecated, so start using the helpers (task_pid_nr/task_pid_vnr/task_pid_nr_ns) in the kernel. The first thing to start with is the pid, printed to dmesg - in this case we may safely use task_pid_nr(). Besides, printks produce more (much more) than a half of all the explicit pid usage. [akpm@linux-foundation.org: git-drm went and changed lots of stuff] Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Cc: Dave Airlie <airlied@linux.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* softlockup: add a /proc tuning parameterRavikiran G Thirumalai2007-10-17
| | | | | | | | | | | | | | | | | | Control the trigger limit for softlockup warnings. This is useful for debugging softlockups, by lowering the softlockup_thresh to identify possible softlockups earlier. This patch: 1. Adds a sysctl softlockup_thresh with valid values of 1-60s (Higher value to disable false positives) 2. Changes the softlockup printk to print the cpu softlockup time [akpm@linux-foundation.org: Fix various warnings and add definition of "two"] Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org> Signed-off-by: Shai Fultheim <shai@scalex86.org> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* softlockup watchdog: style cleanupsIngo Molnar2007-10-17
| | | | | | | | | | | | | | | | kernel/softirq.c grew a few style uncleanlinesses in the past few months, clean that up. No functional changes: text data bss dec hex filename 1126 76 4 1206 4b6 softlockup.o.before 1129 76 4 1209 4b9 softlockup.o.after ( the 3 bytes .text increase is due to the "<1>" appended to one of the printk messages. ) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* softlockup: improve debug outputIngo Molnar2007-10-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Improve the debuggability of kernel lockups by enhancing the debug output of the softlockup detector: print the task that causes the lockup and try to print a more intelligent backtrace. The old format was: BUG: soft lockup detected on CPU#1! [<c0105e4a>] show_trace_log_lvl+0x19/0x2e [<c0105f43>] show_trace+0x12/0x14 [<c0105f59>] dump_stack+0x14/0x16 [<c015f6bc>] softlockup_tick+0xbe/0xd0 [<c013457d>] run_local_timers+0x12/0x14 [<c01346b8>] update_process_times+0x3e/0x63 [<c0145fb8>] tick_sched_timer+0x7c/0xc0 [<c0140a75>] hrtimer_interrupt+0x135/0x1ba [<c011bde7>] smp_apic_timer_interrupt+0x6e/0x80 [<c0105aa3>] apic_timer_interrupt+0x33/0x38 [<c0104f8a>] syscall_call+0x7/0xb ======================= The new format is: BUG: soft lockup detected on CPU#1! [prctl:2363] Pid: 2363, comm: prctl EIP: 0060:[<c013915f>] CPU: 1 EIP is at sys_prctl+0x24/0x18c EFLAGS: 00000213 Not tainted (2.6.22-cfs-v20 #26) EAX: 00000001 EBX: 000003e7 ECX: 00000001 EDX: f6df0000 ESI: 000003e7 EDI: 000003e7 EBP: f6df0fb0 DS: 007b ES: 007b FS: 00d8 CR0: 8005003b CR2: 4d8c3340 CR3: 3731d000 CR4: 000006d0 [<c0105e4a>] show_trace_log_lvl+0x19/0x2e [<c0105f43>] show_trace+0x12/0x14 [<c01040be>] show_regs+0x1ab/0x1b3 [<c015f807>] softlockup_tick+0xef/0x108 [<c013457d>] run_local_timers+0x12/0x14 [<c01346b8>] update_process_times+0x3e/0x63 [<c0145fcc>] tick_sched_timer+0x7c/0xc0 [<c0140a89>] hrtimer_interrupt+0x135/0x1ba [<c011bde7>] smp_apic_timer_interrupt+0x6e/0x80 [<c0105aa3>] apic_timer_interrupt+0x33/0x38 [<c0104f8a>] syscall_call+0x7/0xb ======================= Note that in the old format we only knew that some system call locked up, we didnt know _which_. With the new format we know that it's at a specific place in sys_prctl(). [which was where i created an artificial kernel lockup to test the new format.] This is also useful if the lockup happens in user-space - the user-space EIP (and other registers) will be printed too. (such a lockup would either suggest that the task was running at SCHED_FIFO:99 and looping for more than 10 seconds, or that the softlockup detector has a false-positive.) The task name is printed too first, just in case we dont manage to print a useful backtrace. [satyam@infradead.org: fix warning] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Satyam Sharma <satyam@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fix the softlockup watchdog to actually workIngo Molnar2007-10-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | this Xen related commit: commit 966812dc98e6a7fcdf759cbfa0efab77500a8868 Author: Jeremy Fitzhardinge <jeremy@goop.org> Date: Tue May 8 00:28:02 2007 -0700 Ignore stolen time in the softlockup watchdog broke the softlockup watchdog to never report any lockups. (!) print_timestamp defaults to 0, this makes the following condition always true: if (print_timestamp < (touch_timestamp + 1) || and we'll in essence never report soft lockups. apparently the functionality of the soft lockup watchdog was never actually tested with that patch applied ... Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* softlockup: use cpu_clock() instead of sched_clock()Ingo Molnar2007-10-17
| | | | | | | | sched_clock() is not a reliable time-source, use cpu_clock() instead. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Freezer: make kernel threads nonfreezable by defaultRafael J. Wysocki2007-07-17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, the freezer treats all tasks as freezable, except for the kernel threads that explicitly set the PF_NOFREEZE flag for themselves. This approach is problematic, since it requires every kernel thread to either set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't care for the freezing of tasks at all. It seems better to only require the kernel threads that want to or need to be frozen to use some freezer-related code and to remove any freezer-related code from the other (nonfreezable) kernel threads, which is done in this patch. The patch causes all kernel threads to be nonfreezable by default (ie. to have PF_NOFREEZE set by default) and introduces the set_freezable() function that should be called by the freezable kernel threads in order to unset PF_NOFREEZE. It also makes all of the currently freezable kernel threads call set_freezable(), so it shouldn't cause any (intentional) change of behaviour to appear. Additionally, it updates documentation to describe the freezing of tasks more accurately. [akpm@linux-foundation.org: build fixes] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net> Cc: Pavel Machek <pavel@ucw.cz> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Gautham R Shenoy <ego@in.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Add suspend-related notifications for CPU hotplugRafael J. Wysocki2007-05-09
| | | | | | | | | | | | | | | | | | | | | Since nonboot CPUs are now disabled after tasks and devices have been frozen and the CPU hotplug infrastructure is used for this purpose, we need special CPU hotplug notifications that will help the CPU-hotplug-aware subsystems distinguish normal CPU hotplug events from CPU hotplug events related to a system-wide suspend or resume operation in progress. This patch introduces such notifications and causes them to be used during suspend and resume transitions. It also changes all of the CPU-hotplug-aware subsystems to take these notifications into consideration (for now they are handled in the same way as the corresponding "normal" ones). [oleg@tv-sign.ru: cleanups] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Cc: Gautham R Shenoy <ego@in.ibm.com> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* add touch_all_softlockup_watchdogs()Jeremy Fitzhardinge2007-05-08
| | | | | | | | | | | | | | | | | | | | Add touch_all_softlockup_watchdogs() to allow the softlockup watchdog timers on all cpus to be updated. This is used to prevent sysrq-t from generating a spurious watchdog message when generating lots of output. Softlockup watchdogs use sched_clock() as its timebase, which is inherently per-cpu (at least, when it is measuring unstolen time). Because of this, it isn't possible for one CPU to directly update the other CPU's timers, but it is possible to tell the other CPUs to do update themselves appropriately. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Acked-by: Chris Lalancette <clalance@redhat.com> Signed-off-by: Prarit Bhargava <prarit@redhat.com> Cc: Rick Lindsley <ricklind@us.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Ignore stolen time in the softlockup watchdogJeremy Fitzhardinge2007-05-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The softlockup watchdog is currently a nuisance in a virtual machine, since the whole system could have the CPU stolen from it for a long period of time. While it would be unlikely for a guest domain to be denied timer interrupts for over 10s, it could happen and any softlockup message would be completely spurious. Earlier I proposed that sched_clock() return time in unstolen nanoseconds, which is how Xen and VMI currently implement it. If the softlockup watchdog uses sched_clock() to measure time, it would automatically ignore stolen time, and therefore only report when the guest itself locked up. When running native, sched_clock() returns real-time nanoseconds, so the behaviour would be unchanged. Note that sched_clock() used this way is inherently per-cpu, so this patch makes sure that the per-processor watchdog thread initialized its own timestamp. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: john stultz <johnstul@us.ibm.com> Cc: Zachary Amsden <zach@vmware.com> Cc: James Morris <jmorris@namei.org> Cc: Dan Hecht <dhecht@vmware.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Lalancette <clalance@redhat.com> Cc: Rick Lindsley <ricklind@us.ibm.com> Cc: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* softlockup: s/99/MAX_RT_PRIO/Oleg Nesterov2007-05-08
| | | | | | | | | Don't use hardcoded 99 value, use MAX_RT_PRIO. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] check return value of cpu_callbackAkinobu Mita2006-09-29
| | | | | | | | | | | | | Spawing ksoftirqd, migration, or watchdog, and calling init_timers_cpu() may fail with small memory. If it happens in initcalls, kernel NULL pointer dereference happens later. This patch makes crash happen immediately in such cases. It seems a bit better than getting kernel NULL pointer dereference later. Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Akinobu Mita <mita@miraclelinux.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] cpu hotplug: replace __devinit* with __cpuinit* for cpu notificationsChandra Seetharaman2006-07-31
| | | | | | | | | | | | | | | | Few of the callback functions and notifier blocks that are associated with cpu notifications incorrectly have __devinit and __devinitdata. They should be __cpuinit and __cpuinitdata instead. It makes no functional difference but wastes text area when CONFIG_HOTPLUG is enabled and CONFIG_HOTPLUG_CPU is not. This patch fixes all those instances. Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Cc: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] cpu hotplug: revert initdata patch submitted for 2.6.17Chandra Seetharaman2006-06-27
| | | | | | | | | This patch reverts notifier_block changes made in 2.6.17 Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Cc: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] cpu hotplug: revert init patch submitted for 2.6.17Chandra Seetharaman2006-06-27
| | | | | | | | | | | | | | | | | | | | | In 2.6.17, there was a problem with cpu_notifiers and XFS. I provided a band-aid solution to solve that problem. In the process, i undid all the changes you both were making to ensure that these notifiers were available only at init time (unless CONFIG_HOTPLUG_CPU is defined). We deferred the real fix to 2.6.18. Here is a set of patches that fixes the XFS problem cleanly and makes the cpu notifiers available only at init time (unless CONFIG_HOTPLUG_CPU is defined). If CONFIG_HOTPLUG_CPU is defined then cpu notifiers are available at run time. This patch reverts the notifier_call changes made in 2.6.17 Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Cc: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] cpu hotplug: fix CPU_UP_CANCEL handlingHeiko Carstens2006-06-25
| | | | | | | | | | | | | | If a cpu hotplug callback fails on CPU_UP_PREPARE, all callbacks will be called with CPU_UP_CANCELED. A few of these callbacks assume that on CPU_UP_PREPARE a pointer to task has been stored in a percpu array. This assumption is not true if CPU_UP_PREPARE fails and the following calls to kthread_bind() in CPU_UP_CANCELED will cause an addressing exception because of passing a NULL pointer. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Define __raw_get_cpu_var and use itPaul Mackerras2006-06-25
| | | | | | | | | | | | | | | | | | | | | | | There are several instances of per_cpu(foo, raw_smp_processor_id()), which is semantically equivalent to __get_cpu_var(foo) but without the warning that smp_processor_id() can give if CONFIG_DEBUG_PREEMPT is enabled. For those architectures with optimized per-cpu implementations, namely ia64, powerpc, s390, sparc64 and x86_64, per_cpu() turns into more and slower code than __get_cpu_var(), so it would be preferable to use __get_cpu_var on those platforms. This defines a __raw_get_cpu_var(x) macro which turns into per_cpu(x, raw_smp_processor_id()) on architectures that use the generic per-cpu implementation, and turns into __get_cpu_var(x) on the architectures that have an optimized per-cpu implementation. Signed-off-by: Paul Mackerras <paulus@samba.org> Acked-by: David S. Miller <davem@davemloft.net> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Remove __devinit and __cpuinit from notifier_call definitionsChandra Seetharaman2006-04-26
| | | | | | | | | | | | | Few of the notifier_chain_register() callers use __init in the definition of notifier_call. It is incorrect as the function definition should be available after the initializations (they do not unregister them during initializations). This patch fixes all such usages to _not_ have the notifier_call __init section. Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Remove __devinitdata from notifier block definitionsChandra Seetharaman2006-04-26
| | | | | | | | | | | | | | | | Few of the notifier_chain_register() callers use __devinitdata in the definition of notifier_block data structure. It is incorrect as the data structure should be available after the initializations (they do not unregister them during initializations). This was leading to an oops when notifier_chain_register() call is invoked for those callback chains after initialization. This patch fixes all such usages to _not_ have the notifier_block data structure in the init data section. Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Notifier chain update: API changesAlan Stern2006-03-27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The kernel's implementation of notifier chains is unsafe. There is no protection against entries being added to or removed from a chain while the chain is in use. The issues were discussed in this thread: http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2 We noticed that notifier chains in the kernel fall into two basic usage classes: "Blocking" chains are always called from a process context and the callout routines are allowed to sleep; "Atomic" chains can be called from an atomic context and the callout routines are not allowed to sleep. We decided to codify this distinction and make it part of the API. Therefore this set of patches introduces three new, parallel APIs: one for blocking notifiers, one for atomic notifiers, and one for "raw" notifiers (which is really just the old API under a new name). New kinds of data structures are used for the heads of the chains, and new routines are defined for registration, unregistration, and calling a chain. The three APIs are explained in include/linux/notifier.h and their implementation is in kernel/sys.c. With atomic and blocking chains, the implementation guarantees that the chain links will not be corrupted and that chain callers will not get messed up by entries being added or removed. For raw chains the implementation provides no guarantees at all; users of this API must provide their own protections. (The idea was that situations may come up where the assumptions of the atomic and blocking APIs are not appropriate, so it should be possible for users to handle these things in their own way.) There are some limitations, which should not be too hard to live with. For atomic/blocking chains, registration and unregistration must always be done in a process context since the chain is protected by a mutex/rwsem. Also, a callout routine for a non-raw chain must not try to register or unregister entries on its own chain. (This did happen in a couple of places and the code had to be changed to avoid it.) Since atomic chains may be called from within an NMI handler, they cannot use spinlocks for synchronization. Instead we use RCU. The overhead falls almost entirely in the unregister routine, which is okay since unregistration is much less frequent that calling a chain. Here is the list of chains that we adjusted and their classifications. None of them use the raw API, so for the moment it is only a placeholder. ATOMIC CHAINS ------------- arch/i386/kernel/traps.c: i386die_chain arch/ia64/kernel/traps.c: ia64die_chain arch/powerpc/kernel/traps.c: powerpc_die_chain arch/sparc64/kernel/traps.c: sparc64die_chain arch/x86_64/kernel/traps.c: die_chain drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list kernel/panic.c: panic_notifier_list kernel/profile.c: task_free_notifier net/bluetooth/hci_core.c: hci_notifier net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain net/ipv6/addrconf.c: inet6addr_chain net/netfilter/nf_conntrack_core.c: nf_conntrack_chain net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain net/netlink/af_netlink.c: netlink_chain BLOCKING CHAINS --------------- arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain arch/s390/kernel/process.c: idle_chain arch/x86_64/kernel/process.c idle_notifier drivers/base/memory.c: memory_chain drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list drivers/macintosh/adb.c: adb_client_list drivers/macintosh/via-pmu.c sleep_notifier_list drivers/macintosh/via-pmu68k.c sleep_notifier_list drivers/macintosh/windfarm_core.c wf_client_list drivers/usb/core/notify.c usb_notifier_list drivers/video/fbmem.c fb_notifier_list kernel/cpu.c cpu_chain kernel/module.c module_notify_list kernel/profile.c munmap_notifier kernel/profile.c task_exit_notifier kernel/sys.c reboot_notifier_list net/core/dev.c netdev_chain net/decnet/dn_dev.c: dnaddr_chain net/ipv4/devinet.c: inetaddr_chain It's possible that some of these classifications are wrong. If they are, please let us know or submit a patch to fix them. Note that any chain that gets called very frequently should be atomic, because the rwsem read-locking used for blocking chains is very likely to incur cache misses on SMP systems. (However, if the chain's callout routines may sleep then the chain cannot be atomic.) The patch set was written by Alan Stern and Chandra Seetharaman, incorporating material written by Keith Owens and suggestions from Paul McKenney and Andrew Morton. [jes@sgi.com: restructure the notifier chain initialization macros] Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Jes Sorensen <jes@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] timer irq driven soft watchdog fixAndrew Morton2006-03-25
| | | | | | | | | I seem to have lost this hunk in yesterday's patch. It brings the coming-online CPU's softlockup timer up to date so we don't get false-positive tripups during CPU hot-add. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] timer-irq-driven soft-watchdog, cleanupsIngo Molnar2006-03-24
| | | | | | | | | | | | | | | Make the softlockup detector purely timer-interrupt driven, removing softirq-context (timer) dependencies. This means that if the softlockup watchdog triggers, it has truly observed a longer than 10 seconds scheduling delay of a SCHED_FIFO prio 99 task. (the patch also turns off the softlockup detector during the initial bootup phase and does small style fixes) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] quieten softlockup at bootAnton Blanchard2005-11-09
| | | | | | | | | On a large SMP box we get a lot of softlockup thread XX started lines. Signed-off-by: Anton Blanchard <anton@samba.org> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] cpu hoptlug: avoid usage of smp_processor_id() in preemptible codeHeiko Carstens2005-11-07
| | | | | | | | | | | | | | | | | | | | Replace smp_processor_id() with any_online_cpu(cpu_online_map) in order to avoid lots of "BUG: using smp_processor_id() in preemptible [00000001] code:..." messages in case taking a cpu online fails. All the traces start at the last notifier_call_chain(...) in kernel/cpu.c. Since we hold the cpu_control semaphore it shouldn't be any problem to access cpu_online_map. The reason why cpu_up failed is simply that the cpu that was supposed to be taken online wasn't even there. That is because on s390 we never know when a new cpu comes and therefore cpu_possible_map consists of only ones and doesn't reflect reality. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] detect soft lockupsIngo Molnar2005-09-07
This patch adds a new kernel debug feature: CONFIG_DETECT_SOFTLOCKUP. When enabled then per-CPU watchdog threads are started, which try to run once per second. If they get delayed for more than 10 seconds then a callback from the timer interrupt detects this condition and prints out a warning message and a stack dump (once per lockup incident). The feature is otherwise non-intrusive, it doesnt try to unlock the box in any way, it only gets the debug info out, automatically, and on all CPUs affected by the lockup. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-Off-By: Matthias Urlichs <smurf@smurf.noris.de> Signed-off-by: Richard Purdie <rpurdie@rpsys.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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