• Ingo Molnar's avatar
    softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks · 82a1fcb9
    Ingo Molnar authored
    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: default avatarIngo Molnar <mingo@elte.hu>
    Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
    82a1fcb9
softlockup.c 7.33 KB