linux/kernel/softlockup.c, branch v2.6.25

softlockup: fix task state setting

2008-02-29T17:46:53Z

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 Signed-off-by: Ingo Molnar

debug: softlockup looping fix

2008-02-02T03:27:45Z

Rafael J. Wysocki reported weird, multi-seconds delays during suspend/resume and bisected it back to: commit 82a1fcb90287052aabfa235e7ffc693ea003fe69 Author: Ingo Molnar 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 Signed-off-by: Peter Zijlstra Tested-by: Rafael J. Wysocki Signed-off-by: Ingo Molnar Acked-by: Rafael J. Wysocki Signed-off-by: Linus Torvalds

softlockup: fix signedness

2008-01-25T20:08:34Z

fix softlockup tunables signedness. mark tunables read-mostly. Signed-off-by: Ingo Molnar

softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks

2008-01-25T20:08:02Z

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: [] schedule_timeout+0x6d/0x8b [] schedule_timeout_uninterruptible+0x15/0x17 [] msleep+0x10/0x16 [] sys_prctl+0x30/0x1e2 [] sysenter_past_esp+0x5f/0xa5 ======================= 2 locks held by prctl/3042: #0: (&sb->s_type->i_mutex_key#5){--..}, at: [] do_fsync+0x38/0x7a #1: (jbd_handle){--..}, at: [] 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 : CPU hotplug fixes. ] [ Andrew Morton : build warning fix. ] Signed-off-by: Ingo Molnar Signed-off-by: Arjan van de Ven

Use helpers to obtain task pid in printks

2007-10-19T18:53:43Z

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 Cc: Dave Airlie Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

softlockup: add a /proc tuning parameter

2007-10-17T15:42:47Z

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 Signed-off-by: Shai Fultheim Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

softlockup watchdog: style cleanups

2007-10-17T15:42:47Z

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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

softlockup: improve debug output

2007-10-17T15:42:47Z

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! [] show_trace_log_lvl+0x19/0x2e [] show_trace+0x12/0x14 [] dump_stack+0x14/0x16 [] softlockup_tick+0xbe/0xd0 [] run_local_timers+0x12/0x14 [] update_process_times+0x3e/0x63 [] tick_sched_timer+0x7c/0xc0 [] hrtimer_interrupt+0x135/0x1ba [] smp_apic_timer_interrupt+0x6e/0x80 [] apic_timer_interrupt+0x33/0x38 [] syscall_call+0x7/0xb ======================= The new format is: BUG: soft lockup detected on CPU#1! [prctl:2363] Pid: 2363, comm: prctl EIP: 0060:[] 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 [] show_trace_log_lvl+0x19/0x2e [] show_trace+0x12/0x14 [] show_regs+0x1ab/0x1b3 [] softlockup_tick+0xef/0x108 [] run_local_timers+0x12/0x14 [] update_process_times+0x3e/0x63 [] tick_sched_timer+0x7c/0xc0 [] hrtimer_interrupt+0x135/0x1ba [] smp_apic_timer_interrupt+0x6e/0x80 [] apic_timer_interrupt+0x33/0x38 [] 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 Signed-off-by: Satyam Sharma Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fix the softlockup watchdog to actually work

2007-10-17T15:42:47Z

this Xen related commit: commit 966812dc98e6a7fcdf759cbfa0efab77500a8868 Author: Jeremy Fitzhardinge 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 Cc: Jeremy Fitzhardinge Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

softlockup: use cpu_clock() instead of sched_clock()

2007-10-17T15:42:46Z

sched_clock() is not a reliable time-source, use cpu_clock() instead. Signed-off-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds