)]}'
{
  "commit": "1423cc033df017c762a9155eec470da77a460141",
  "tree": "5f44bf17e3df58eeccdd33de8d9d43466d3518e8",
  "parents": [
    "684ca5cc9a772532bc893cdc994bd89bf0773719"
  ],
  "author": {
    "name": "Paul E. McKenney",
    "email": "paulmck@linux.vnet.ibm.com",
    "time": "Tue Aug 18 23:06:14 2009 -0700"
  },
  "committer": {
    "name": "Ingo Molnar",
    "email": "mingo@elte.hu",
    "time": "Wed Aug 19 13:58:54 2009 +0200"
  },
  "message": "rcu: Delay rcu_barrier() wait until beginning of next CPU-hotunplug operation.\n\nIngo Molnar reported this lockup:\n\n [  200.380003] Hangcheck: hangcheck value past margin!\n [  248.192003] INFO: task S99local:2974 blocked for more than 120 seconds.\n [  248.194532] \"echo 0 \u003e /proc/sys/kernel/hung_task_timeout_secs\" disables this message.\n [  248.202330] S99local      D 0000000c  6256  2974   2687 0x00000000\n [  248.208929]  9c7ebe90 00000086 6b67ef8b 0000000c 9f25a610 81a69869 00000001 820b6990\n [  248.216123]  820b6990 820b6990 9c6e4c20 9c6e4eb4 82c78990 00000000 6b993559 0000000c\n [  248.220616]  9c7ebe90 8105f22a 9c6e4eb4 9c6e4c20 00000001 9c7ebe98 9c7ebeb4 81a65cb3\n [  248.229990] Call Trace:\n [  248.234049]  [\u003c81a69869\u003e] ? _spin_unlock_irqrestore+0x22/0x37\n [  248.239769]  [\u003c8105f22a\u003e] ? prepare_to_wait+0x48/0x4e\n [  248.244796]  [\u003c81a65cb3\u003e] rcu_barrier_cpu_hotplug+0xaa/0xc9\n [  248.250343]  [\u003c8105f029\u003e] ? autoremove_wake_function+0x0/0x38\n [  248.256063]  [\u003c81062cf2\u003e] notifier_call_chain+0x49/0x71\n [  248.261263]  [\u003c81062da0\u003e] raw_notifier_call_chain+0x11/0x13\n [  248.266809]  [\u003c81a0b475\u003e] _cpu_down+0x272/0x288\n [  248.271316]  [\u003c81a0b4d5\u003e] cpu_down+0x4a/0xa2\n [  248.275563]  [\u003c81a0c48a\u003e] store_online+0x2a/0x5e\n [  248.280156]  [\u003c81a0c460\u003e] ? store_online+0x0/0x5e\n [  248.284836]  [\u003c814ddc35\u003e] sysdev_store+0x20/0x28\n [  248.289429]  [\u003c8112e403\u003e] sysfs_write_file+0xb8/0xe3\n [  248.294369]  [\u003c8112e34b\u003e] ? sysfs_write_file+0x0/0xe3\n [  248.299396]  [\u003c810e4c8f\u003e] vfs_write+0x91/0x120\n [  248.303817]  [\u003c810e4dc1\u003e] sys_write+0x40/0x65\n [  248.308150]  [\u003c81002d73\u003e] sysenter_do_call+0x12/0x28\n\nThis change moves an RCU grace period delay off of the\ncritical path for CPU-hotunplug operations.\n\nSince RCU callback migration is only performed on\nCPU-hotunplug operations, and since the rcu_barrier() race is\nprovoked only by consecutive CPU-hotunplug operations, it is\nnot necessary to delay the end of a given CPU-hotunplug\noperation.\n\nWe can instead choose to delay the beginning of the next\nCPU-hotunplug operation.\n\nReported-by: Ingo Molnar \u003cmingo@elte.hu\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: Josh Triplett \u003cjosht@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: akpm@linux-foundation.org\nCc: mathieu.desnoyers@polymtl.ca\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: hugh.dickins@tiscali.co.uk\nCc: benh@kernel.crashing.org\nLKML-Reference: \u003c20090819060614.GA14383@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n",
  "tree_diff": [
    {
      "type": "modify",
      "old_id": "8df115600c2d301e530eac440ac2863f71b3c414",
      "old_mode": 33188,
      "old_path": "kernel/rcupdate.c",
      "new_id": "bd5d5c8e51408343f3067a80611d5d1fed8ca89d",
      "new_mode": 33188,
      "new_path": "kernel/rcupdate.c"
    }
  ]
}