)]}' { "log": [ { "commit": "e90c53d3e238dd0b7b02964370e8fece1778df96", "tree": "23e5b8623c2c37bd8a4656c66266209872f80701", "parents": [ "5b61b0baa9e80289c53413e573befc5790a04ac7" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Sat Aug 20 18:29:32 2011 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Sep 28 21:38:48 2011 -0700" }, "message": "rcu: Remove rcu_needs_cpu_flush() to avoid false quiescent states\n\nThe purpose of rcu_needs_cpu_flush() was to iterate on pushing the\ncurrent grace period in order to help the current CPU enter dyntick-idle\nmode. However, this can result in failures if the CPU starts entering\ndyntick-idle mode, but then backs out. In this case, the call to\nrcu_pending() from rcu_needs_cpu_flush() might end up announcing a\nnon-existing quiescent state.\n\nThis commit therefore removes rcu_needs_cpu_flush() in favor of letting\nthe dyntick-idle machinery at the end of the softirq handler push the\nloop along via its call to rcu_pending().\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "9bc8b5586f94be6391458074ecbba8827ba8ba9d", "tree": "323804bb7180337c266f88519cea6b1f42114ead", "parents": [ "037067a1b6f9a70f862f3ed9d59fe28b7cd55ac4" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Sat Aug 13 13:31:47 2011 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Sep 28 21:38:41 2011 -0700" }, "message": "rcu: Suppress NMI backtraces when stall ends before dump\n\nIt is possible for an RCU CPU stall to end just as it is detected, in\nwhich case the current code will uselessly dump all CPU\u0027s stacks.\nThis commit therefore checks for this condition and refrains from\nsending needless NMIs.\n\nAnd yes, the stall might also end just after we checked all CPUs and\ntasks, but in that case we would at least have given some clue as\nto which CPU/task was at fault.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "e4cc1f22b2f4e9b0207a8cdb63e56dcf99e82d35", "tree": "ec3fad6587f0a83e764a571394bdfb85a84edf30", "parents": [ "d4c08f2ac311a360230eef7e5395b0ec8d8f0670" ], "author": { "name": "Paul E. McKenney", "email": "paul.mckenney@linaro.org", "time": "Mon Jun 27 00:17:43 2011 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Sep 28 21:38:22 2011 -0700" }, "message": "rcu: Simplify quiescent-state accounting\n\nThere is often a delay between the time that a CPU passes through a\nquiescent state and the time that this quiescent state is reported to the\nRCU core. It is quite possible that the grace period ended before the\nquiescent state could be reported, for example, some other CPU might have\ndeduced that this CPU passed through dyntick-idle mode. It is critically\nimportant that quiescent state be counted only against the grace period\nthat was in effect at the time that the quiescent state was detected.\n\nPreviously, this was handled by recording the number of the last grace\nperiod to complete when passing through a quiescent state. The RCU\ncore then checks this number against the current value, and rejects\nthe quiescent state if there is a mismatch. However, one additional\npossibility must be accounted for, namely that the quiescent state was\nrecorded after the prior grace period completed but before the current\ngrace period started. In this case, the RCU core must reject the\nquiescent state, but the recorded number will match. This is handled\nwhen the CPU becomes aware of a new grace period -- at that point,\nit invalidates any prior quiescent state.\n\nThis works, but is a bit indirect. The new approach records the current\ngrace period, and the RCU core checks to see (1) that this is still the\ncurrent grace period and (2) that this grace period has not yet ended.\nThis approach simplifies reasoning about correctness, and this commit\nchanges over to this new approach.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "d4c08f2ac311a360230eef7e5395b0ec8d8f0670", "tree": "06e425b8153e076fbe43b037cf4497ac50afddb7", "parents": [ "965a002b4f1a458c5dcb334ec29f48a0046faa25" ], "author": { "name": "Paul E. McKenney", "email": "paul.mckenney@linaro.org", "time": "Sat Jun 25 06:36:56 2011 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Sep 28 21:38:21 2011 -0700" }, "message": "rcu: Add grace-period, quiescent-state, and call_rcu trace events\n\nAdd trace events to record grace-period start and end, quiescent states,\nCPUs noticing grace-period start and end, grace-period initialization,\ncall_rcu() invocation, tasks blocking in RCU read-side critical sections,\ntasks exiting those same critical sections, force_quiescent_state()\ndetection of dyntick-idle and offline CPUs, CPUs entering and leaving\ndyntick-idle mode (except from NMIs), CPUs coming online and going\noffline, and CPUs being kicked for staying in dyntick-idle mode for too\nlong (as in many weeks, even on 32-bit systems).\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n\nrcu: Add the rcu flavor to callback trace events\n\nThe earlier trace events for registering RCU callbacks and for invoking\nthem did not include the RCU flavor (rcu_bh, rcu_preempt, or rcu_sched).\nThis commit adds the RCU flavor to those trace events.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "eab0993c7ba5c7d9b3613d6037e0f31f0ccbe181", "tree": "9f37a94506e2c58d7d0139374bc21b64b9e073ed", "parents": [ "e0f23060adfa3f27beaa7918eff70258b88471b6" ], "author": { "name": "Paul E. McKenney", "email": "paul.mckenney@linaro.org", "time": "Tue Jun 21 01:59:33 2011 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Sep 28 21:38:18 2011 -0700" }, "message": "rcu: Move RCU_BOOST declarations to allow compiler checking\n\nAndi Kleen noticed that one of the RCU_BOOST data declarations was\nout of sync with the definition. Move the declarations so that the\ncompiler can do the checking in the future.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "f8b7fc6b514f34a51875dd48dff70d4d17a54f38", "tree": "dc6583851e3536516761b0fd9b07f5a3a1743ebb", "parents": [ "a46e0899eec7a3069bcadd45dfba7bf67c6ed016" ], "author": { "name": "Paul E. McKenney", "email": "paul.mckenney@linaro.org", "time": "Thu Jun 16 08:26:32 2011 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu Jun 16 16:12:05 2011 -0700" }, "message": "rcu: Move RCU_BOOST #ifdefs to header file\n\nThe commit \"use softirq instead of kthreads except when RCU_BOOST\u003dy\"\njust applied #ifdef in place. This commit is a cleanup that moves\nthe newly #ifdef\u0027ed code to the header file kernel/rcutree_plugin.h.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "a46e0899eec7a3069bcadd45dfba7bf67c6ed016", "tree": "78158b4056fe1365d5086f66769abdc3ef2643c3", "parents": [ "09223371deac67d08ca0b70bd18787920284c967" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Jun 15 15:47:09 2011 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Jun 15 23:07:21 2011 -0700" }, "message": "rcu: use softirq instead of kthreads except when RCU_BOOST\u003dy\n\nThis patch #ifdefs RCU kthreads out of the kernel unless RCU_BOOST\u003dy,\nthus eliminating context-switch overhead if RCU priority boosting has\nnot been configured.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "09223371deac67d08ca0b70bd18787920284c967", "tree": "0ad0354a93ac209c8cfd2b79d03d0462aa3c5c58", "parents": [ "9a432736904d386cda28b987b38ba14dae960ecc" ], "author": { "name": "Shaohua Li", "email": "shaohua.li@intel.com", "time": "Tue Jun 14 13:26:25 2011 +0800" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Tue Jun 14 15:25:39 2011 -0700" }, "message": "rcu: Use softirq to address performance regression\n\nCommit a26ac2455ffcf3(rcu: move TREE_RCU from softirq to kthread)\nintroduced performance regression. In an AIM7 test, this commit degraded\nperformance by about 40%.\n\nThe commit runs rcu callbacks in a kthread instead of softirq. We observed\nhigh rate of context switch which is caused by this. Out test system has\n64 CPUs and HZ is 1000, so we saw more than 64k context switch per second\nwhich is caused by RCU\u0027s per-CPU kthread. A trace showed that most of\nthe time the RCU per-CPU kthread doesn\u0027t actually handle any callbacks,\nbut instead just does a very small amount of work handling grace periods.\nThis means that RCU\u0027s per-CPU kthreads are making the scheduler do quite\na bit of work in order to allow a very small amount of RCU-related\nprocessing to be done.\n\nAlex Shi\u0027s analysis determined that this slowdown is due to lock\ncontention within the scheduler. Unfortunately, as Peter Zijlstra points\nout, the scheduler\u0027s real-time semantics require global action, which\nmeans that this contention is inherent in real-time scheduling. (Yes,\nperhaps someone will come up with a workaround -- otherwise, -rt is not\ngoing to do well on large SMP systems -- but this patch will work around\nthis issue in the meantime. And \"the meantime\" might well be forever.)\n\nThis patch therefore re-introduces softirq processing to RCU, but only\nfor core RCU work. RCU callbacks are still executed in kthread context,\nso that only a small amount of RCU work runs in softirq context in the\ncommon case. This should minimize ksoftirqd execution, allowing us to\nskip boosting of ksoftirqd for CONFIG_RCU_BOOST\u003dy kernels.\n\nSigned-off-by: Shaohua Li \u003cshaohua.li@intel.com\u003e\nTested-by: \"Alex,Shi\" \u003calex.shi@intel.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "08bca60a6912ad225254250c0a9c3a05b4152cfa", "tree": "760b20e6eaaa02412fcecb6bc5c3598b6bc0fdce", "parents": [ "8826f3b0397562eee6f8785d548be9dfdb169100" ], "author": { "name": "Peter Zijlstra", "email": "a.p.zijlstra@chello.nl", "time": "Fri May 20 16:06:29 2011 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Sat May 28 17:41:52 2011 +0200" }, "message": "rcu: Remove waitqueue usage for cpu, node, and boost kthreads\n\nIt is not necessary to use waitqueues for the RCU kthreads because\nwe always know exactly which thread is to be awakened. In addition,\nwake_up() only issues an actual wakeup when there is a thread waiting on\nthe queue, which was why there was an extra explicit wake_up_process()\nto get the RCU kthreads started.\n\nEliminating the waitqueues (and wake_up()) in favor of wake_up_process()\neliminates the need for the initial wake_up_process() and also shrinks\nthe data structure size a bit. The wakeup logic is placed in a new\nrcu_wait() macro.\n\nSigned-off-by: Peter Zijlstra \u003ca.p.zijlstra@chello.nl\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "8826f3b0397562eee6f8785d548be9dfdb169100", "tree": "3b911e0ffe56b1792126f3f36f1fa4de39fd5979", "parents": [ "55c2945aa9d4d907ec5ca4f6a4e30ae908d8d30d" ], "author": { "name": "Paul E. McKenney", "email": "paul.mckenney@linaro.org", "time": "Wed May 11 05:41:41 2011 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Sat May 28 17:41:49 2011 +0200" }, "message": "rcu: Avoid acquiring rcu_node locks in timer functions\n\nThis commit switches manipulations of the rcu_node -\u003ewakemask field\nto atomic operations, which allows rcu_cpu_kthread_timer() to avoid\nacquiring the rcu_node lock. This should avoid the following lockdep\nsplat reported by Valdis Kletnieks:\n\n[ 12.872150] usb 1-4: new high speed USB device number 3 using ehci_hcd\n[ 12.986667] usb 1-4: New USB device found, idVendor\u003d413c, idProduct\u003d2513\n[ 12.986679] usb 1-4: New USB device strings: Mfr\u003d0, Product\u003d0, SerialNumber\u003d0\n[ 12.987691] hub 1-4:1.0: USB hub found\n[ 12.987877] hub 1-4:1.0: 3 ports detected\n[ 12.996372] input: PS/2 Generic Mouse as /devices/platform/i8042/serio1/input/input10\n[ 13.071471] udevadm used greatest stack depth: 3984 bytes left\n[ 13.172129]\n[ 13.172130] \u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\u003d\n[ 13.172425] [ INFO: possible circular locking dependency detected ]\n[ 13.172650] 2.6.39-rc6-mmotm0506 #1\n[ 13.172773] -------------------------------------------------------\n[ 13.172997] blkid/267 is trying to acquire lock:\n[ 13.173009] (\u0026p-\u003epi_lock){-.-.-.}, at: [\u003cffffffff81032d8f\u003e] try_to_wake_up+0x29/0x1aa\n[ 13.173009]\n[ 13.173009] but task is already holding lock:\n[ 13.173009] (rcu_node_level_0){..-...}, at: [\u003cffffffff810901cc\u003e] rcu_cpu_kthread_timer+0x27/0x58\n[ 13.173009]\n[ 13.173009] which lock already depends on the new lock.\n[ 13.173009]\n[ 13.173009]\n[ 13.173009] the existing dependency chain (in reverse order) is:\n[ 13.173009]\n[ 13.173009] -\u003e #2 (rcu_node_level_0){..-...}:\n[ 13.173009] [\u003cffffffff810679b9\u003e] check_prevs_add+0x8b/0x104\n[ 13.173009] [\u003cffffffff81067da1\u003e] validate_chain+0x36f/0x3ab\n[ 13.173009] [\u003cffffffff8106846b\u003e] __lock_acquire+0x369/0x3e2\n[ 13.173009] [\u003cffffffff81068a0f\u003e] lock_acquire+0xfc/0x14c\n[ 13.173009] [\u003cffffffff815697f1\u003e] _raw_spin_lock+0x36/0x45\n[ 13.173009] [\u003cffffffff81090794\u003e] rcu_read_unlock_special+0x8c/0x1d5\n[ 13.173009] [\u003cffffffff8109092c\u003e] __rcu_read_unlock+0x4f/0xd7\n[ 13.173009] [\u003cffffffff81027bd3\u003e] rcu_read_unlock+0x21/0x23\n[ 13.173009] [\u003cffffffff8102cc34\u003e] cpuacct_charge+0x6c/0x75\n[ 13.173009] [\u003cffffffff81030cc6\u003e] update_curr+0x101/0x12e\n[ 13.173009] [\u003cffffffff810311d0\u003e] check_preempt_wakeup+0xf7/0x23b\n[ 13.173009] [\u003cffffffff8102acb3\u003e] check_preempt_curr+0x2b/0x68\n[ 13.173009] [\u003cffffffff81031d40\u003e] ttwu_do_wakeup+0x76/0x128\n[ 13.173009] [\u003cffffffff81031e49\u003e] ttwu_do_activate.constprop.63+0x57/0x5c\n[ 13.173009] [\u003cffffffff81031e96\u003e] scheduler_ipi+0x48/0x5d\n[ 13.173009] [\u003cffffffff810177d5\u003e] smp_reschedule_interrupt+0x16/0x18\n[ 13.173009] [\u003cffffffff815710f3\u003e] reschedule_interrupt+0x13/0x20\n[ 13.173009] [\u003cffffffff810b66d1\u003e] rcu_read_unlock+0x21/0x23\n[ 13.173009] [\u003cffffffff810b739c\u003e] find_get_page+0xa9/0xb9\n[ 13.173009] [\u003cffffffff810b8b48\u003e] filemap_fault+0x6a/0x34d\n[ 13.173009] [\u003cffffffff810d1a25\u003e] __do_fault+0x54/0x3e6\n[ 13.173009] [\u003cffffffff810d447a\u003e] handle_pte_fault+0x12c/0x1ed\n[ 13.173009] [\u003cffffffff810d48f7\u003e] handle_mm_fault+0x1cd/0x1e0\n[ 13.173009] [\u003cffffffff8156cfee\u003e] do_page_fault+0x42d/0x5de\n[ 13.173009] [\u003cffffffff8156a75f\u003e] page_fault+0x1f/0x30\n[ 13.173009]\n[ 13.173009] -\u003e #1 (\u0026rq-\u003elock){-.-.-.}:\n[ 13.173009] [\u003cffffffff810679b9\u003e] check_prevs_add+0x8b/0x104\n[ 13.173009] [\u003cffffffff81067da1\u003e] validate_chain+0x36f/0x3ab\n[ 13.173009] [\u003cffffffff8106846b\u003e] __lock_acquire+0x369/0x3e2\n[ 13.173009] [\u003cffffffff81068a0f\u003e] lock_acquire+0xfc/0x14c\n[ 13.173009] [\u003cffffffff815697f1\u003e] _raw_spin_lock+0x36/0x45\n[ 13.173009] [\u003cffffffff81027e19\u003e] __task_rq_lock+0x8b/0xd3\n[ 13.173009] [\u003cffffffff81032f7f\u003e] wake_up_new_task+0x41/0x108\n[ 13.173009] [\u003cffffffff810376c3\u003e] do_fork+0x265/0x33f\n[ 13.173009] [\u003cffffffff81007d02\u003e] kernel_thread+0x6b/0x6d\n[ 13.173009] [\u003cffffffff8153a9dd\u003e] rest_init+0x21/0xd2\n[ 13.173009] [\u003cffffffff81b1db4f\u003e] start_kernel+0x3bb/0x3c6\n[ 13.173009] [\u003cffffffff81b1d29f\u003e] x86_64_start_reservations+0xaf/0xb3\n[ 13.173009] [\u003cffffffff81b1d393\u003e] x86_64_start_kernel+0xf0/0xf7\n[ 13.173009]\n[ 13.173009] -\u003e #0 (\u0026p-\u003epi_lock){-.-.-.}:\n[ 13.173009] [\u003cffffffff81067788\u003e] check_prev_add+0x68/0x20e\n[ 13.173009] [\u003cffffffff810679b9\u003e] check_prevs_add+0x8b/0x104\n[ 13.173009] [\u003cffffffff81067da1\u003e] validate_chain+0x36f/0x3ab\n[ 13.173009] [\u003cffffffff8106846b\u003e] __lock_acquire+0x369/0x3e2\n[ 13.173009] [\u003cffffffff81068a0f\u003e] lock_acquire+0xfc/0x14c\n[ 13.173009] [\u003cffffffff815698ea\u003e] _raw_spin_lock_irqsave+0x44/0x57\n[ 13.173009] [\u003cffffffff81032d8f\u003e] try_to_wake_up+0x29/0x1aa\n[ 13.173009] [\u003cffffffff81032f3c\u003e] wake_up_process+0x10/0x12\n[ 13.173009] [\u003cffffffff810901e9\u003e] rcu_cpu_kthread_timer+0x44/0x58\n[ 13.173009] [\u003cffffffff81045286\u003e] call_timer_fn+0xac/0x1e9\n[ 13.173009] [\u003cffffffff8104556d\u003e] run_timer_softirq+0x1aa/0x1f2\n[ 13.173009] [\u003cffffffff8103e487\u003e] __do_softirq+0x109/0x26a\n[ 13.173009] [\u003cffffffff8157144c\u003e] call_softirq+0x1c/0x30\n[ 13.173009] [\u003cffffffff81003207\u003e] do_softirq+0x44/0xf1\n[ 13.173009] [\u003cffffffff8103e8b9\u003e] irq_exit+0x58/0xc8\n[ 13.173009] [\u003cffffffff81017f5a\u003e] smp_apic_timer_interrupt+0x79/0x87\n[ 13.173009] [\u003cffffffff81570fd3\u003e] apic_timer_interrupt+0x13/0x20\n[ 13.173009] [\u003cffffffff810bd51a\u003e] get_page_from_freelist+0x2aa/0x310\n[ 13.173009] [\u003cffffffff810bdf03\u003e] __alloc_pages_nodemask+0x178/0x243\n[ 13.173009] [\u003cffffffff8101fe2f\u003e] pte_alloc_one+0x1e/0x3a\n[ 13.173009] [\u003cffffffff810d27fe\u003e] __pte_alloc+0x22/0x14b\n[ 13.173009] [\u003cffffffff810d48a8\u003e] handle_mm_fault+0x17e/0x1e0\n[ 13.173009] [\u003cffffffff8156cfee\u003e] do_page_fault+0x42d/0x5de\n[ 13.173009] [\u003cffffffff8156a75f\u003e] page_fault+0x1f/0x30\n[ 13.173009]\n[ 13.173009] other info that might help us debug this:\n[ 13.173009]\n[ 13.173009] Chain exists of:\n[ 13.173009] \u0026p-\u003epi_lock --\u003e \u0026rq-\u003elock --\u003e rcu_node_level_0\n[ 13.173009]\n[ 13.173009] Possible unsafe locking scenario:\n[ 13.173009]\n[ 13.173009] CPU0 CPU1\n[ 13.173009] ---- ----\n[ 13.173009] lock(rcu_node_level_0);\n[ 13.173009] lock(\u0026rq-\u003elock);\n[ 13.173009] lock(rcu_node_level_0);\n[ 13.173009] lock(\u0026p-\u003epi_lock);\n[ 13.173009]\n[ 13.173009] *** DEADLOCK ***\n[ 13.173009]\n[ 13.173009] 3 locks held by blkid/267:\n[ 13.173009] #0: (\u0026mm-\u003emmap_sem){++++++}, at: [\u003cffffffff8156cdb4\u003e] do_page_fault+0x1f3/0x5de\n[ 13.173009] #1: (\u0026yield_timer){+.-...}, at: [\u003cffffffff810451da\u003e] call_timer_fn+0x0/0x1e9\n[ 13.173009] #2: (rcu_node_level_0){..-...}, at: [\u003cffffffff810901cc\u003e] rcu_cpu_kthread_timer+0x27/0x58\n[ 13.173009]\n[ 13.173009] stack backtrace:\n[ 13.173009] Pid: 267, comm: blkid Not tainted 2.6.39-rc6-mmotm0506 #1\n[ 13.173009] Call Trace:\n[ 13.173009] \u003cIRQ\u003e [\u003cffffffff8154a529\u003e] print_circular_bug+0xc8/0xd9\n[ 13.173009] [\u003cffffffff81067788\u003e] check_prev_add+0x68/0x20e\n[ 13.173009] [\u003cffffffff8100c861\u003e] ? save_stack_trace+0x28/0x46\n[ 13.173009] [\u003cffffffff810679b9\u003e] check_prevs_add+0x8b/0x104\n[ 13.173009] [\u003cffffffff81067da1\u003e] validate_chain+0x36f/0x3ab\n[ 13.173009] [\u003cffffffff8106846b\u003e] __lock_acquire+0x369/0x3e2\n[ 13.173009] [\u003cffffffff81032d8f\u003e] ? try_to_wake_up+0x29/0x1aa\n[ 13.173009] [\u003cffffffff81068a0f\u003e] lock_acquire+0xfc/0x14c\n[ 13.173009] [\u003cffffffff81032d8f\u003e] ? try_to_wake_up+0x29/0x1aa\n[ 13.173009] [\u003cffffffff810901a5\u003e] ? rcu_check_quiescent_state+0x82/0x82\n[ 13.173009] [\u003cffffffff815698ea\u003e] _raw_spin_lock_irqsave+0x44/0x57\n[ 13.173009] [\u003cffffffff81032d8f\u003e] ? try_to_wake_up+0x29/0x1aa\n[ 13.173009] [\u003cffffffff81032d8f\u003e] try_to_wake_up+0x29/0x1aa\n[ 13.173009] [\u003cffffffff810901a5\u003e] ? rcu_check_quiescent_state+0x82/0x82\n[ 13.173009] [\u003cffffffff81032f3c\u003e] wake_up_process+0x10/0x12\n[ 13.173009] [\u003cffffffff810901e9\u003e] rcu_cpu_kthread_timer+0x44/0x58\n[ 13.173009] [\u003cffffffff810901a5\u003e] ? rcu_check_quiescent_state+0x82/0x82\n[ 13.173009] [\u003cffffffff81045286\u003e] call_timer_fn+0xac/0x1e9\n[ 13.173009] [\u003cffffffff810451da\u003e] ? del_timer+0x75/0x75\n[ 13.173009] [\u003cffffffff810901a5\u003e] ? rcu_check_quiescent_state+0x82/0x82\n[ 13.173009] [\u003cffffffff8104556d\u003e] run_timer_softirq+0x1aa/0x1f2\n[ 13.173009] [\u003cffffffff8103e487\u003e] __do_softirq+0x109/0x26a\n[ 13.173009] [\u003cffffffff8106365f\u003e] ? tick_dev_program_event+0x37/0xf6\n[ 13.173009] [\u003cffffffff810a0e4a\u003e] ? time_hardirqs_off+0x1b/0x2f\n[ 13.173009] [\u003cffffffff8157144c\u003e] call_softirq+0x1c/0x30\n[ 13.173009] [\u003cffffffff81003207\u003e] do_softirq+0x44/0xf1\n[ 13.173009] [\u003cffffffff8103e8b9\u003e] irq_exit+0x58/0xc8\n[ 13.173009] [\u003cffffffff81017f5a\u003e] smp_apic_timer_interrupt+0x79/0x87\n[ 13.173009] [\u003cffffffff81570fd3\u003e] apic_timer_interrupt+0x13/0x20\n[ 13.173009] \u003cEOI\u003e [\u003cffffffff810bd384\u003e] ? get_page_from_freelist+0x114/0x310\n[ 13.173009] [\u003cffffffff810bd51a\u003e] ? get_page_from_freelist+0x2aa/0x310\n[ 13.173009] [\u003cffffffff812220e7\u003e] ? clear_page_c+0x7/0x10\n[ 13.173009] [\u003cffffffff810bd1ef\u003e] ? prep_new_page+0x14c/0x1cd\n[ 13.173009] [\u003cffffffff810bd51a\u003e] get_page_from_freelist+0x2aa/0x310\n[ 13.173009] [\u003cffffffff810bdf03\u003e] __alloc_pages_nodemask+0x178/0x243\n[ 13.173009] [\u003cffffffff810d46b9\u003e] ? __pmd_alloc+0x87/0x99\n[ 13.173009] [\u003cffffffff8101fe2f\u003e] pte_alloc_one+0x1e/0x3a\n[ 13.173009] [\u003cffffffff810d46b9\u003e] ? __pmd_alloc+0x87/0x99\n[ 13.173009] [\u003cffffffff810d27fe\u003e] __pte_alloc+0x22/0x14b\n[ 13.173009] [\u003cffffffff810d48a8\u003e] handle_mm_fault+0x17e/0x1e0\n[ 13.173009] [\u003cffffffff8156cfee\u003e] do_page_fault+0x42d/0x5de\n[ 13.173009] [\u003cffffffff810d915f\u003e] ? sys_brk+0x32/0x10c\n[ 13.173009] [\u003cffffffff810a0e4a\u003e] ? time_hardirqs_off+0x1b/0x2f\n[ 13.173009] [\u003cffffffff81065c4f\u003e] ? trace_hardirqs_off_caller+0x3f/0x9c\n[ 13.173009] [\u003cffffffff812235dd\u003e] ? trace_hardirqs_off_thunk+0x3a/0x3c\n[ 13.173009] [\u003cffffffff8156a75f\u003e] page_fault+0x1f/0x30\n[ 14.010075] usb 5-1: new full speed USB device number 2 using uhci_hcd\n\nReported-by: Valdis Kletnieks \u003cValdis.Kletnieks@vt.edu\u003e\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "23b5c8fa01b723c70a20d6e4ef4ff54c7656d6e1", "tree": "d03faad5e19848b35a019793b9a1cbc0bb68a708", "parents": [ "4305ce7894dd38b0633bfc8978437320119223bd" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Tue Sep 07 10:38:22 2010 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu May 26 09:42:23 2011 -0700" }, "message": "rcu: Decrease memory-barrier usage based on semi-formal proof\n\n(Note: this was reverted, and is now being re-applied in pieces, with\nthis being the fifth and final piece. See below for the reason that\nit is now felt to be safe to re-apply this.)\n\nCommit d09b62d fixed grace-period synchronization, but left some smp_mb()\ninvocations in rcu_process_callbacks() that are no longer needed, but\nsheer paranoia prevented them from being removed. This commit removes\nthem and provides a proof of correctness in their absence. It also adds\na memory barrier to rcu_report_qs_rsp() immediately before the update to\nrsp-\u003ecompleted in order to handle the theoretical possibility that the\ncompiler or CPU might move massive quantities of code into a lock-based\ncritical section. This also proves that the sheer paranoia was not\nentirely unjustified, at least from a theoretical point of view.\n\nIn addition, the old dyntick-idle synchronization depended on the fact\nthat grace periods were many milliseconds in duration, so that it could\nbe assumed that no dyntick-idle CPU could reorder a memory reference\nacross an entire grace period. Unfortunately for this design, the\naddition of expedited grace periods breaks this assumption, which has\nthe unfortunate side-effect of requiring atomic operations in the\nfunctions that track dyntick-idle state for RCU. (There is some hope\nthat the algorithms used in user-level RCU might be applied here, but\nsome work is required to handle the NMIs that user-space applications\ncan happily ignore. For the short term, better safe than sorry.)\n\nThis proof assumes that neither compiler nor CPU will allow a lock\nacquisition and release to be reordered, as doing so can result in\ndeadlock. The proof is as follows:\n\n1.\tA given CPU declares a quiescent state under the protection of\n\tits leaf rcu_node\u0027s lock.\n\n2.\tIf there is more than one level of rcu_node hierarchy, the\n\tlast CPU to declare a quiescent state will also acquire the\n\t-\u003elock of the next rcu_node up in the hierarchy, but only\n\tafter releasing the lower level\u0027s lock. The acquisition of this\n\tlock clearly cannot occur prior to the acquisition of the leaf\n\tnode\u0027s lock.\n\n3.\tStep 2 repeats until we reach the root rcu_node structure.\n\tPlease note again that only one lock is held at a time through\n\tthis process. The acquisition of the root rcu_node\u0027s -\u003elock\n\tmust occur after the release of that of the leaf rcu_node.\n\n4.\tAt this point, we set the -\u003ecompleted field in the rcu_state\n\tstructure in rcu_report_qs_rsp(). However, if the rcu_node\n\thierarchy contains only one rcu_node, then in theory the code\n\tpreceding the quiescent state could leak into the critical\n\tsection. We therefore precede the update of -\u003ecompleted with a\n\tmemory barrier. All CPUs will therefore agree that any updates\n\tpreceding any report of a quiescent state will have happened\n\tbefore the update of -\u003ecompleted.\n\n5.\tRegardless of whether a new grace period is needed, rcu_start_gp()\n\twill propagate the new value of -\u003ecompleted to all of the leaf\n\trcu_node structures, under the protection of each rcu_node\u0027s -\u003elock.\n\tIf a new grace period is needed immediately, this propagation\n\twill occur in the same critical section that -\u003ecompleted was\n\tset in, but courtesy of the memory barrier in #4 above, is still\n\tseen to follow any pre-quiescent-state activity.\n\n6.\tWhen a given CPU invokes __rcu_process_gp_end(), it becomes\n\taware of the end of the old grace period and therefore makes\n\tany RCU callbacks that were waiting on that grace period eligible\n\tfor invocation.\n\n\tIf this CPU is the same one that detected the end of the grace\n\tperiod, and if there is but a single rcu_node in the hierarchy,\n\twe will still be in the single critical section. In this case,\n\tthe memory barrier in step #4 guarantees that all callbacks will\n\tbe seen to execute after each CPU\u0027s quiescent state.\n\n\tOn the other hand, if this is a different CPU, it will acquire\n\tthe leaf rcu_node\u0027s -\u003elock, and will again be serialized after\n\teach CPU\u0027s quiescent state for the old grace period.\n\nOn the strength of this proof, this commit therefore removes the memory\nbarriers from rcu_process_callbacks() and adds one to rcu_report_qs_rsp().\nThe effect is to reduce the number of memory barriers by one and to\nreduce the frequency of execution from about once per scheduling tick\nper CPU to once per grace period.\n\nThis was reverted do to hangs found during testing by Yinghai Lu and\nIngo Molnar. Frederic Weisbecker supplied Yinghai with tracing that\nlocated the underlying problem, and Frederic also provided the fix.\n\nThe underlying problem was that the HARDIRQ_ENTER() macro from\nlib/locking-selftest.c invoked irq_enter(), which in turn invokes\nrcu_irq_enter(), but HARDIRQ_EXIT() invoked __irq_exit(), which\ndoes not invoke rcu_irq_exit(). This situation resulted in calls\nto rcu_irq_enter() that were not balanced by the required calls to\nrcu_irq_exit(). Therefore, after these locking selftests completed,\nRCU\u0027s dyntick-idle nesting count was a large number (for example,\n72), which caused RCU to to conclude that the affected CPU was not in\ndyntick-idle mode when in fact it was.\n\nRCU would therefore incorrectly wait for this dyntick-idle CPU, resulting\nin hangs.\n\nIn contrast, with Frederic\u0027s patch, which replaces the irq_enter()\nin HARDIRQ_ENTER() with an __irq_enter(), these tests don\u0027t ever call\neither rcu_irq_enter() or rcu_irq_exit(), which works because the CPU\nrunning the test is already marked as not being in dyntick-idle mode.\nThis means that the rcu_irq_enter() and rcu_irq_exit() calls and RCU\nthen has no problem working out which CPUs are in dyntick-idle mode and\nwhich are not.\n\nThe reason that the imbalance was not noticed before the barrier patch\nwas applied is that the old implementation of rcu_enter_nohz() ignored\nthe nesting depth. This could still result in delays, but much shorter\nones. Whenever there was a delay, RCU would IPI the CPU with the\nunbalanced nesting level, which would eventually result in rcu_enter_nohz()\nbeing called, which in turn would force RCU to see that the CPU was in\ndyntick-idle mode.\n\nThe reason that very few people noticed the problem is that the mismatched\nirq_enter() vs. __irq_exit() occured only when the kernel was built with\nCONFIG_DEBUG_LOCKING_API_SELFTESTS.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n" }, { "commit": "80d02085d99039b3b7f3a73c8896226b0cb1ba07", "tree": "c310902423ecb00effadcb59c60cbf118d4037cb", "parents": [ "11c476f31a0fabc6e604da5b09a6590b57c3fb20" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu May 12 01:08:07 2011 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Thu May 19 23:25:29 2011 +0200" }, "message": "Revert \"rcu: Decrease memory-barrier usage based on semi-formal proof\"\n\nThis reverts commit e59fb3120becfb36b22ddb8bd27d065d3cdca499.\n\nThis reversion was due to (extreme) boot-time slowdowns on SPARC seen by\nYinghai Lu and on x86 by Ingo\n.\nThis is a non-trivial reversion due to intervening commits.\n\nConflicts:\n\n\tDocumentation/RCU/trace.txt\n\tkernel/rcutree.c\n\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "1217ed1ba5c67393293dfb0f03c353b118dadeb4", "tree": "a765356c8418e134de85fd05d9fe6eda41de859c", "parents": [ "29ce831000081dd757d3116bf774aafffc4b6b20" ], "author": { "name": "Paul E. McKenney", "email": "paul.mckenney@linaro.org", "time": "Wed May 04 21:43:49 2011 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Sat May 07 22:50:45 2011 -0700" }, "message": "rcu: permit rcu_read_unlock() to be called while holding runqueue locks\n\nAvoid calling into the scheduler while holding core RCU locks. This\nallows rcu_read_unlock() to be called while holding the runqueue locks,\nbut only as long as there was no chance of the RCU read-side critical\nsection having been preempted. (Otherwise, if RCU priority boosting\nis enabled, rcu_read_unlock() might call into the scheduler in order to\nunboost itself, which might allows self-deadlock on the runqueue locks\nwithin the scheduler.)\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "6cc68793e380bb51f447d8d02af873b7bc01f222", "tree": "f2b66ace23acc0a31a08f136ad25659d6b51c4b1", "parents": [ "13491a0ee1ef862b6c842132b6eb9c5e721af5ad" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Mar 02 13:15:15 2011 -0800" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu May 05 23:16:59 2011 -0700" }, "message": "rcu: fix spelling\n\nThe \"preemptible\" spelling is preferable. May as well fix it.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n" }, { "commit": "15ba0ba860871cf74b48b1bb47c26c91a66126f3", "tree": "2043eeca7d6df62fc0ae918b61abada073f81415", "parents": [ "a9f4793d8900dc5dc09b3951bdcd4731290e06fe" ], "author": { "name": "Paul E. McKenney", "email": "paul.mckenney@linaro.org", "time": "Wed Apr 06 16:01:16 2011 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu May 05 23:16:56 2011 -0700" }, "message": "rcu: add grace-period age and more kthread state to tracing\n\nThis commit adds the age in jiffies of the current grace period along\nwith the duration in jiffies of the longest grace period since boot\nto the rcu/rcugp debugfs file. It also adds an additional \"O\" state\nto kthread tracing to differentiate between the kthread waiting due to\nhaving nothing to do on the one hand and waiting due to being on the\nwrong CPU on the other hand.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "d71df90eadfc35aa549ff9a850842673febca71f", "tree": "dd275a3f4848784bc6625574341c11befc1b3823", "parents": [ "0ac3d136b2e3cdf1161178223bc5da14a06241d0" ], "author": { "name": "Paul E. McKenney", "email": "paul.mckenney@linaro.org", "time": "Tue Mar 29 17:48:28 2011 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu May 05 23:16:56 2011 -0700" }, "message": "rcu: add tracing for RCU\u0027s kthread run states.\n\nAdd tracing to help debugging situations when RCU\u0027s kthreads are not\nrunning but are supposed to be.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n" }, { "commit": "0ea1f2ebeb217d38770aebf91c4ecaa8e01b3305", "tree": "ef558d2eb804ca033a5166d24f5b4be7cf87727f", "parents": [ "67b98dba474f293c389fc2b7254dcf7c0492e3bd" ], "author": { "name": "Paul E. McKenney", "email": "paul.mckenney@linaro.org", "time": "Tue Feb 22 13:42:43 2011 -0800" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu May 05 23:16:55 2011 -0700" }, "message": "rcu: Add boosting to TREE_PREEMPT_RCU tracing\n\nIncludes total number of tasks boosted, number boosted on behalf of each\nof normal and expedited grace periods, and statistics on attempts to\ninitiate boosting that failed for various reasons.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n" }, { "commit": "27f4d28057adf98750cf863c40baefb12f5b6d21", "tree": "a66584d2cb68cebda327313f78b8f4eb602ed4ef", "parents": [ "a26ac2455ffcf3be5c6ef92bc6df7182700f2114" ], "author": { "name": "Paul E. McKenney", "email": "paul.mckenney@linaro.org", "time": "Mon Feb 07 12:47:15 2011 -0800" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu May 05 23:16:55 2011 -0700" }, "message": "rcu: priority boosting for TREE_PREEMPT_RCU\n\nAdd priority boosting for TREE_PREEMPT_RCU, similar to that for\nTINY_PREEMPT_RCU. This is enabled by the default-off RCU_BOOST\nkernel parameter. The priority to which to boost preempted\nRCU readers is controlled by the RCU_BOOST_PRIO kernel parameter\n(defaulting to real-time priority 1) and the time to wait before\nboosting the readers who are blocking a given grace period is\ncontrolled by the RCU_BOOST_DELAY kernel parameter (defaulting to\n500 milliseconds).\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n" }, { "commit": "a26ac2455ffcf3be5c6ef92bc6df7182700f2114", "tree": "601697c7c3fd152a1b3f29f43d3a028fc8fefd5f", "parents": [ "12f5f524cafef3ab689929b118f2dfb8bf2be321" ], "author": { "name": "Paul E. McKenney", "email": "paul.mckenney@linaro.org", "time": "Wed Jan 12 14:10:23 2011 -0800" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu May 05 23:16:54 2011 -0700" }, "message": "rcu: move TREE_RCU from softirq to kthread\n\nIf RCU priority boosting is to be meaningful, callback invocation must\nbe boosted in addition to preempted RCU readers. Otherwise, in presence\nof CPU real-time threads, the grace period ends, but the callbacks don\u0027t\nget invoked. If the callbacks don\u0027t get invoked, the associated memory\ndoesn\u0027t get freed, so the system is still subject to OOM.\n\nBut it is not reasonable to priority-boost RCU_SOFTIRQ, so this commit\nmoves the callback invocations to a kthread, which can be boosted easily.\n\nAlso add comments and properly synchronized all accesses to\nrcu_cpu_kthread_task, as suggested by Lai Jiangshan.\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n" }, { "commit": "12f5f524cafef3ab689929b118f2dfb8bf2be321", "tree": "639473556b6edf9b79e0a18d5ba58f80eea76519", "parents": [ "e59fb3120becfb36b22ddb8bd27d065d3cdca499" ], "author": { "name": "Paul E. McKenney", "email": "paul.mckenney@linaro.org", "time": "Mon Nov 29 21:56:39 2010 -0800" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu May 05 23:16:54 2011 -0700" }, "message": "rcu: merge TREE_PREEPT_RCU blocked_tasks[] lists\n\nCombine the current TREE_PREEMPT_RCU -\u003eblocked_tasks[] lists in the\nrcu_node structure into a single -\u003eblkd_tasks list with -\u003egp_tasks\nand -\u003eexp_tasks tail pointers. This is in preparation for RCU priority\nboosting, which will add a third dimension to the combinatorial explosion\nin the -\u003eblocked_tasks[] case, but simply a third pointer in the new\n-\u003eblkd_tasks case.\n\nAlso update documentation to reflect blocked_tasks[] merge\n\nSigned-off-by: Paul E. McKenney \u003cpaul.mckenney@linaro.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n" }, { "commit": "e59fb3120becfb36b22ddb8bd27d065d3cdca499", "tree": "37eaadfe112b64caae943fc7469274bc96553d92", "parents": [ "a00e0d714fbded07a7a2254391ce9ed5a5cb9d82" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Tue Sep 07 10:38:22 2010 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu May 05 23:16:54 2011 -0700" }, "message": "rcu: Decrease memory-barrier usage based on semi-formal proof\n\nCommit d09b62d fixed grace-period synchronization, but left some smp_mb()\ninvocations in rcu_process_callbacks() that are no longer needed, but\nsheer paranoia prevented them from being removed. This commit removes\nthem and provides a proof of correctness in their absence. It also adds\na memory barrier to rcu_report_qs_rsp() immediately before the update to\nrsp-\u003ecompleted in order to handle the theoretical possibility that the\ncompiler or CPU might move massive quantities of code into a lock-based\ncritical section. This also proves that the sheer paranoia was not\nentirely unjustified, at least from a theoretical point of view.\n\nIn addition, the old dyntick-idle synchronization depended on the fact\nthat grace periods were many milliseconds in duration, so that it could\nbe assumed that no dyntick-idle CPU could reorder a memory reference\nacross an entire grace period. Unfortunately for this design, the\naddition of expedited grace periods breaks this assumption, which has\nthe unfortunate side-effect of requiring atomic operations in the\nfunctions that track dyntick-idle state for RCU. (There is some hope\nthat the algorithms used in user-level RCU might be applied here, but\nsome work is required to handle the NMIs that user-space applications\ncan happily ignore. For the short term, better safe than sorry.)\n\nThis proof assumes that neither compiler nor CPU will allow a lock\nacquisition and release to be reordered, as doing so can result in\ndeadlock. The proof is as follows:\n\n1.\tA given CPU declares a quiescent state under the protection of\n\tits leaf rcu_node\u0027s lock.\n\n2.\tIf there is more than one level of rcu_node hierarchy, the\n\tlast CPU to declare a quiescent state will also acquire the\n\t-\u003elock of the next rcu_node up in the hierarchy, but only\n\tafter releasing the lower level\u0027s lock. The acquisition of this\n\tlock clearly cannot occur prior to the acquisition of the leaf\n\tnode\u0027s lock.\n\n3.\tStep 2 repeats until we reach the root rcu_node structure.\n\tPlease note again that only one lock is held at a time through\n\tthis process. The acquisition of the root rcu_node\u0027s -\u003elock\n\tmust occur after the release of that of the leaf rcu_node.\n\n4.\tAt this point, we set the -\u003ecompleted field in the rcu_state\n\tstructure in rcu_report_qs_rsp(). However, if the rcu_node\n\thierarchy contains only one rcu_node, then in theory the code\n\tpreceding the quiescent state could leak into the critical\n\tsection. We therefore precede the update of -\u003ecompleted with a\n\tmemory barrier. All CPUs will therefore agree that any updates\n\tpreceding any report of a quiescent state will have happened\n\tbefore the update of -\u003ecompleted.\n\n5.\tRegardless of whether a new grace period is needed, rcu_start_gp()\n\twill propagate the new value of -\u003ecompleted to all of the leaf\n\trcu_node structures, under the protection of each rcu_node\u0027s -\u003elock.\n\tIf a new grace period is needed immediately, this propagation\n\twill occur in the same critical section that -\u003ecompleted was\n\tset in, but courtesy of the memory barrier in #4 above, is still\n\tseen to follow any pre-quiescent-state activity.\n\n6.\tWhen a given CPU invokes __rcu_process_gp_end(), it becomes\n\taware of the end of the old grace period and therefore makes\n\tany RCU callbacks that were waiting on that grace period eligible\n\tfor invocation.\n\n\tIf this CPU is the same one that detected the end of the grace\n\tperiod, and if there is but a single rcu_node in the hierarchy,\n\twe will still be in the single critical section. In this case,\n\tthe memory barrier in step #4 guarantees that all callbacks will\n\tbe seen to execute after each CPU\u0027s quiescent state.\n\n\tOn the other hand, if this is a different CPU, it will acquire\n\tthe leaf rcu_node\u0027s -\u003elock, and will again be serialized after\n\teach CPU\u0027s quiescent state for the old grace period.\n\nOn the strength of this proof, this commit therefore removes the memory\nbarriers from rcu_process_callbacks() and adds one to rcu_report_qs_rsp().\nThe effect is to reduce the number of memory barriers by one and to\nreduce the frequency of execution from about once per scheduling tick\nper CPU to once per grace period.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n" }, { "commit": "a00e0d714fbded07a7a2254391ce9ed5a5cb9d82", "tree": "7c213dbf1e2561655d07749b6d689027460fb8cc", "parents": [ "0ee5623f9a6e52df90a78bd21179f8ab370e102e" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Tue Feb 08 17:14:39 2011 -0800" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu May 05 23:16:54 2011 -0700" }, "message": "rcu: Remove conditional compilation for RCU CPU stall warnings\n\nThe RCU CPU stall warnings can now be controlled using the\nrcu_cpu_stall_suppress boot-time parameter or via the same parameter\nfrom sysfs. There is therefore no longer any reason to have\nkernel config parameters for this feature. This commit therefore\nremoves the RCU_CPU_STALL_DETECTOR and RCU_CPU_STALL_DETECTOR_RUNNABLE\nkernel config parameters. The RCU_CPU_STALL_TIMEOUT parameter remains\nto allow the timeout to be tuned and the RCU_CPU_STALL_VERBOSE parameter\nremains to allow task-stall information to be suppressed if desired.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n" }, { "commit": "0209f6490b030f35349a2bb71294f3fd75b0f36d", "tree": "159e233c6fcaf63fbb1a18f5db54af38a8336ee3", "parents": [ "121dfc4b3eba9e2f3c42d35205a3510cc65b9931" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Tue Dec 14 16:07:52 2010 -0800" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Fri Dec 17 12:34:20 2010 -0800" }, "message": "rcu: limit rcu_node leaf-level fanout\n\nSome recent benchmarks have indicated possible lock contention on the\nleaf-level rcu_node locks. This commit therefore limits the number of\nCPUs per leaf-level rcu_node structure to 16, in other words, there\ncan be at most 16 rcu_data structures fanning into a given rcu_node\nstructure. Prior to this, the limit was 32 on 32-bit systems and 64 on\n64-bit systems.\n\nNote that the fanout of non-leaf rcu_node structures is unchanged. The\norganization of accesses to the rcu_node tree is such that references\nto non-leaf rcu_node structures are much less frequent than to the\nleaf structures.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "29494be71afe2a16ad04e344306a620d7cc22d06", "tree": "d16a2acd1566be326483d5217d39b78d2ef798c5", "parents": [ "7b27d5475f86186914e54e4a6bb994e9a985337b" ], "author": { "name": "Lai Jiangshan", "email": "laijs@cn.fujitsu.com", "time": "Wed Oct 20 14:13:06 2010 +0800" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Mon Nov 29 22:01:58 2010 -0800" }, "message": "rcu,cleanup: simplify the code when cpu is dying\n\nWhen we handle the CPU_DYING notifier, the whole system is stopped except\nfor the current CPU. We therefore need no synchronization with the other\nCPUs. This allows us to move any orphaned RCU callbacks directly to the\nlist of any online CPU without needing to run them through the global\norphan lists. These global orphan lists can therefore be dispensed with.\nThis commit makes thes changes, though currently victimizes CPU 0 @@@.\n\nSigned-off-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "269dcc1c2ec25864308ee03a3fa26ea819d9f5d0", "tree": "1c81ee6a9151ab1580628f6e9f85c469ceccb5c0", "parents": [ "0ddea0ead2ced99eaaaddff2beb755381e5c89f8" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Tue Sep 07 14:23:09 2010 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu Sep 23 09:16:53 2010 -0700" }, "message": "rcu: Add tracing data to support queueing models\n\nThe current tracing data is not sufficient to deduce the average time\nthat a callback spends waiting for a grace period to end. Add three\nper-CPU counters recording the number of callbacks invoked (ci), the\nnumber of callbacks orphaned (co), and the number of callbacks adopted\n(ca). Given the existing callback queue length (ql), the average wait\ntime in absence of CPU hotplug operations is ql/ci. The units of wait\ntime will be in terms of the duration over which ci was measured.\n\nIn the presence of CPU hotplug operations, there is room for argument,\nbut ql/(ci-co+ca) won\u0027t steer you too far wrong.\n\nAlso fixes a typo called out by Lucas De Marchi \u003clucas.de.marchi@gmail.com\u003e.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "a3dc3fb161f9b4066c0fce22db72638af8baf83b", "tree": "e41a30edd7e4965807b199da7637a6d6e44d4ed1", "parents": [ "53d84e004d5e8c018be395c4330dc72fd60bd13e" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Fri Aug 13 16:16:25 2010 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Fri Aug 20 09:00:13 2010 -0700" }, "message": "rcu: repair code-duplication FIXMEs\n\nCombine the duplicate definitions of ULONG_CMP_GE(), ULONG_CMP_LT(),\nand rcu_preempt_depth() into include/linux/rcupdate.h.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "53d84e004d5e8c018be395c4330dc72fd60bd13e", "tree": "6d5b265442ac42c7cc73147b0de0d029644e312b", "parents": [ "8cdd32a918350430483751feaae1c19cef816f69" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Tue Aug 10 14:28:53 2010 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Fri Aug 20 09:00:12 2010 -0700" }, "message": "rcu: permit suppressing current grace period\u0027s CPU stall warnings\n\nWhen using a kernel debugger, a long sojourn in the debugger can get\nyou lots of RCU CPU stall warnings once you resume. This might not be\nhelpful, especially if you are using the system console. This patch\ntherefore allows RCU CPU stall warnings to be suppressed, but only for\nthe duration of the current set of grace periods.\n\nThis differs from Jason\u0027s original patch in that it adds support for\ntiny RCU and preemptible RCU, and uses a slightly different method for\nsuppressing the RCU CPU stall warning messages.\n\nSigned-off-by: Jason Wessel \u003cjason.wessel@windriver.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nTested-by: Jason Wessel \u003cjason.wessel@windriver.com\u003e\n" }, { "commit": "910b1b7e19a292ff685001caf1bf1a9775b771a1", "tree": "7ec42bf018ab62c3c2180fbe168cd6130556cb80", "parents": [ "687d7a960aea46e016182c7ce346d62c4dbd0366" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Jul 21 08:05:56 2010 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu Aug 19 17:18:04 2010 -0700" }, "message": "rcu: Allow RCU CPU stall warnings to be off at boot, but manually enablable\n\nCurrently, if RCU CPU stall warnings are enabled, they are enabled\nimmediately upon boot. They can be manually disabled via /sys (and\nalso re-enabled via /sys), and are automatically disabled upon panic.\nHowever, some users need RCU CPU stalls to be disabled at boot time,\nbut to be enabled without rebuilding/rebooting. For example, someone\nrunning a real-time application in production might not want the\nadditional latency of RCU CPU stall detection in normal operation, but\nmight need to enable it at any point for fault isolation purposes.\n\nThis commit therefore provides a new CONFIG_RCU_CPU_STALL_DETECTOR_RUNNABLE\nkernel configuration parameter that maintains the current behavior\n(enable at boot) by default, but allows a kernel to be configured\nwith RCU CPU stall detection built into the kernel, but disabled at\nboot time.\n\nRequested-by: Clark Williams \u003cwilliams@redhat.com\u003e\nRequested-by: John Kacur \u003cjkacur@redhat.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "b163760e37047781b37c412cde54d146ac4b651f", "tree": "5b447a210c81b78e20393472f4b53623c8fed28b", "parents": [ "4221a9918e38b7494cee341dda7b7b4bb8c04bde" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Jun 02 16:21:38 2010 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu Aug 19 17:18:02 2010 -0700" }, "message": "rcu: make CPU stall warning timeout configurable\n\nAlso set the default to 60 seconds, up from the previous hard-coded timeout\nof 10 seconds. This allows people who care to set short timeouts, while\navoiding people with unusual configurations (make randconfig!!!) from being\nbothered with spurious CPU stall warnings.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n" }, { "commit": "394f99a9007d4274f7076bb8553ab0ff9707688b", "tree": "7d379f91321cec58b87fd5f5089947872689d591", "parents": [ "e546f485e1d7520ca0200502cdcc11b503f4805c" ], "author": { "name": "Lai Jiangshan", "email": "laijs@cn.fujitsu.com", "time": "Mon Jun 28 16:25:04 2010 +0800" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu Aug 19 17:18:01 2010 -0700" }, "message": "rcu: simplify the usage of percpu data\n\n\u0026percpu_data is compatible with allocated percpu data.\n\nAnd we use it and remove the \"-\u003erda[NR_CPUS]\" array, saving significant\nstorage on systems with large numbers of CPUs. This does add an additional\nlevel of indirection and thus an additional cache line referenced, but\nbecause -\u003erda is not used on the read side, this is OK.\n\nSigned-off-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nReviewed-by: Tejun Heo \u003ctj@kernel.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nReviewed-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\n" }, { "commit": "d21670acab9fcb4bc74a40b68a6941059234c55c", "tree": "6a4c054bc4dbadf0524b4e221889a8da558dbdaf", "parents": [ "4a90a0681cf6cd21cd444184302aa045156486b3" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Apr 14 17:39:26 2010 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Mon May 10 11:08:35 2010 -0700" }, "message": "rcu: reduce the number of spurious RCU_SOFTIRQ invocations\n\nLai Jiangshan noted that up to 10% of the RCU_SOFTIRQ are spurious, and\ntraced this down to the fact that the current grace-period machinery\nwill uselessly raise RCU_SOFTIRQ when a given CPU needs to go through\na quiescent state, but has not yet done so. In this situation, there\nmight well be nothing that RCU_SOFTIRQ can do, and the overhead can be\nworth worrying about in the ksoftirqd case. This patch therefore avoids\nraising RCU_SOFTIRQ in this situation.\n\nChanges since v1 (http://lkml.org/lkml/2010/3/30/122 from Lai Jiangshan):\n\no\tOmit the rcu_qs_pending() prechecks, as they aren\u0027t that\n\tmuch less expensive than the quiescent-state checks.\n\no\tMerge with the set_need_resched() patch that reduces IPIs.\n\no\tAdd the new n_rp_report_qs field to the rcu_pending tracing output.\n\no\tUpdate the tracing documentation accordingly.\n\nSigned-off-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "4300aa642cc9ecb35f2e0683dd294fb790ef028c", "tree": "b70d676b02c6311a638fdaa6f3df8773b39fade1", "parents": [ "26845c2860cebebe6ce2d9d01ae3cb3db84b7e29" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Tue Apr 13 16:18:22 2010 -0700" }, "committer": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Mon May 10 11:08:34 2010 -0700" }, "message": "rcu: improve RCU CPU stall-warning messages\n\nThe existing RCU CPU stall-warning messages can be confusing, especially\nin the case where one CPU detects a single other stalled CPU. In addition,\nthe console messages did not say which flavor of RCU detected the stall,\nwhich can make it difficult to work out exactly what is causing the stall.\nThis commit improves these messages.\n\nRequested-by: Dhaval Giani \u003cdhaval.giani@gmail.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\n" }, { "commit": "007b09243b099811124f69d492adeebe9e439f96", "tree": "fc80fcd1f6c5dfcb37144f4d17507d22cbbc0c11", "parents": [ "3f379b03fbfddd20536389a85c6456f8233d1f8d" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Fri Mar 05 15:03:26 2010 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Thu Mar 11 13:38:01 2010 +0100" }, "message": "rcu: Increase RCU CPU stall timeouts if PROVE_RCU\n\nCONFIG_PROVE_RCU imposes additional overhead on the kernel, so\nincrease the RCU CPU stall timeouts in an attempt to allow for\nthis effect.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1267830207-9474-2-git-send-email-paulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "a47cd880b50e14b0b6f5e9d426ae9a2676c9c474", "tree": "c134dcec52450ec92ea853f4aeeef8e3967a36cb", "parents": [ "f5f654096487c6d526c47bb66308f9de81f091cf" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Fri Feb 26 16:38:56 2010 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Sat Feb 27 09:53:52 2010 +0100" }, "message": "rcu: Fix accelerated grace periods for last non-dynticked CPU\n\nIt is invalid to invoke __rcu_process_callbacks() with irqs\ndisabled, so do it indirectly via raise_softirq(). This\nrequires a state-machine implementation to cycle through the\ngrace-period machinery the required number of times.\n\nLocated-by: Ingo Molnar \u003cmingo@elte.hu\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1267231138-27856-1-git-send-email-paulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "1ed509a225008c9e8c0644fbd22168e09a7383a0", "tree": "db65a58258bb968e7bc922dab14f4f0714a7667e", "parents": [ "6155fec92e85f07d99e9746234496215443ffb0d" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Mon Feb 22 17:05:05 2010 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Thu Feb 25 10:35:02 2010 +0100" }, "message": "rcu: Add RCU_CPU_STALL_VERBOSE to dump detailed per-task information\n\nWhen RCU detects a grace-period stall, it currently just prints\nout the PID of any tasks doing the stalling. This patch adds\nRCU_CPU_STALL_VERBOSE, which enables the more-verbose reporting\nfrom sched_show_task().\n\nSuggested-by: Thomas Gleixner \u003ctglx@linutronix.de\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1266887105-1528-21-git-send-email-paulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "1304afb225288a2e250d6a7495462c28e5509cbb", "tree": "1ba76e304f718f7ce89532e1c4d276b4af439c07", "parents": [ "20133cfce7d0bbdcc0c398301030c091f5675c88" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Mon Feb 22 17:05:02 2010 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Thu Feb 25 10:34:58 2010 +0100" }, "message": "rcu: Convert to raw_spinlocks\n\nThe spinlocks in rcutree need to be real spinlocks in\npreempt-rt. Convert them to raw_spinlocks.\n\nSigned-off-by: Thomas Gleixner \u003ctglx@linutronix.de\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1266887105-1528-18-git-send-email-paulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "20133cfce7d0bbdcc0c398301030c091f5675c88", "tree": "337f242bfc89f5880cf86234fa6b574f52a2f0a5", "parents": [ "1bd22e374b20c2f0ba1d2723c1f585acab2251c5" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Mon Feb 22 17:05:01 2010 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Thu Feb 25 10:34:57 2010 +0100" }, "message": "rcu: Stop overflowing signed integers\n\nThe C standard does not specify the result of an operation that\noverflows a signed integer, so such operations need to be\navoided. This patch changes the type of several fields from\n\"long\" to \"unsigned long\" and adjusts operations as needed.\nULONG_CMP_GE() and ULONG_CMP_LT() macros are introduced to do\nthe modular comparisons that are appropriate given that overflow\nis an expected event.\n\nAcked-by: Mathieu Desnoyers \u003cmathieu.desnoyers@efficios.com\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1266887105-1528-17-git-send-email-paulmck@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "017c426138122c8e9b9f5057fbd0567c37b35247", "tree": "648d35f773bc08e83d06f0c02a68cae02c46a4cd", "parents": [ "4c54005ca438a8b46dd542b497d4f0dc2ca375e8" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu Jan 14 16:10:58 2010 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Sat Jan 16 10:25:22 2010 +0100" }, "message": "rcu: Fix sparse warnings\n\nRename local variable \"i\" in rcu_init() to avoid conflict with\nRCU_INIT_FLAVOR(), restrict the scope of RCU_TREE_NONCORE, and\nmake __synchronize_srcu() static.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12635142581560-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "46a1e34eda805501a8b32f26394faa435149f6d1", "tree": "56359434e348fce6ffc8701fb4948dee1cb4c91f", "parents": [ "45f014c52eef022873b19d6a20eb0ec9668f2b09" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Mon Jan 04 15:09:09 2010 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Wed Jan 13 09:06:05 2010 +0100" }, "message": "rcu: Make force_quiescent_state() start grace period if needed\n\nGrace periods cannot be started while force_quiescent_state() is\nactive. This is OK in that the affected CPUs will try again\nlater, but it does induce needless grace-period delays. This\npatch causes rcu_start_gp() to record a failed attempt to start\na grace period. When force_quiescent_state() prepares to return,\nit then starts the grace period if there was such a failed\nattempt.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12626465501854-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "ee47eb9f4da6f44af965d6d049e77ee8c8a4b822", "tree": "bc500b12150bd47afd34b24fd1db90939f5fec3b", "parents": [ "0f10dc826646134dce3e5751512b87d30f3903e4" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Mon Jan 04 15:09:07 2010 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Wed Jan 13 09:06:04 2010 +0100" }, "message": "rcu: Remove leg of force_quiescent_state() switch statement\n\nThe comparisons of rsp-\u003egpnum nad rsp-\u003ecompleted in\nrcu_process_dyntick() and force_quiescent_state() can be\nreplaced by the much more clear rcu_gp_in_progress() predicate\nfunction. After doing this, it becomes clear that the\nRCU_SAVE_COMPLETED leg of the force_quiescent_state() function\u0027s\nswitch statement is almost completely a no-op. A small change\nto the RCU_SAVE_DYNTICK leg renders it a complete no-op, after\nwhich it can be removed. Doing so also eliminates the forcenow\nlocal variable from force_quiescent_state().\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12626465501781-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "39c0bbfc07c6e28db7346d0e11106f2d045d3035", "tree": "82f0fdacb1eea0334e76e0adb8b9d5beec66f2a7", "parents": [ "f3a8b5c6aa543bd87764418d63632eb65b80e2f6" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Mon Jan 04 15:09:04 2010 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Wed Jan 13 09:06:03 2010 +0100" }, "message": "rcu: Eliminate local variable lastcomp from force_quiescent_state()\n\nBecause rsp-\u003efqs_active is set to 1 across\nforce_quiescent_state()\u0027s switch statement, rcu_start_gp() will\nrefrain from starting a new grace period during this time.\nTherefore, rsp-\u003egpnum is constant, and can be propagated to all\nuses of lastcomp, eliminating this local variable.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12626465502985-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "07079d5357a4d53c2b13126c4a38fb40e6e04966", "tree": "1a97552a220a9bbdfceb1cda01c1ee5b92ce75bd", "parents": [ "559569acf94f538b56bd6eead80b439d6a78cdff" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Mon Jan 04 15:09:02 2010 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Wed Jan 13 09:06:02 2010 +0100" }, "message": "rcu: Prohibit starting new grace periods while forcing quiescent states\n\nReduce the number and variety of race conditions by prohibiting\nthe start of a new grace period while force_quiescent_state() is\nactive. A new fqs_active flag in the rcu_state structure is used\nto trace whether or not force_quiescent_state() is active, and\nthis new flag is tested by rcu_start_gp(). If the CPU that\nclosed out the last grace period needs another grace period,\nthis new grace period may be delayed up to one scheduling-clock\ntick, but it will eventually get started.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c126264655052-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "d9a3da0699b24a589b27a61e1a5b5bd30d9db669", "tree": "f7440e396a6c818f3cef514ccc31ab55d88025ef", "parents": [ "cf244dc01bf68e1ad338b82447f8686d24ea4435" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Dec 02 12:10:15 2009 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Thu Dec 03 11:35:25 2009 +0100" }, "message": "rcu: Add expedited grace-period support for preemptible RCU\n\nImplement an synchronize_rcu_expedited() for preemptible RCU\nthat actually is expedited. This uses\nsynchronize_sched_expedited() to force all threads currently\nrunning in a preemptible-RCU read-side critical section onto the\nappropriate -\u003eblocked_tasks[] list, then takes a snapshot of all\nof these lists and waits for them to drain.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1259784616158-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "cf244dc01bf68e1ad338b82447f8686d24ea4435", "tree": "dc2aebb60ef1eddf92d7e23b72ec2f6c08797684", "parents": [ "d3f6bad3911736e44ba11f3f3f6ac4e8c837fdfc" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Dec 02 12:10:14 2009 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Thu Dec 03 11:34:53 2009 +0100" }, "message": "rcu: Enable fourth level of TREE_RCU hierarchy\n\nEnable a fourth level of rcu_node hierarchy for TREE_RCU and\nTREE_PREEMPT_RCU. This is for stress-testing and experiemental\npurposes only, although in theory this would enable 16,777,216\nCPUs on 64-bit systems, though only 1,048,576 CPUs on 32-bit\nsystems. Normal experimental use of this fourth level will\nnormally set CONFIG_RCU_FANOUT\u003d2, requiring a 16-CPU system,\nthough the more adventurous (and more fortunate) experimenters\nmay wish to chose CONFIG_RCU_FANOUT\u003d3 for 81-CPU systems or even\nCONFIG_RCU_FANOUT\u003d4 for 256-CPU systems.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nAcked-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\nAcked-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12597846161257-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "d3f6bad3911736e44ba11f3f3f6ac4e8c837fdfc", "tree": "55b0c2e11ab3ec02e9065cf3d46ffd20386dfed2", "parents": [ "6ebb237bece23275d1da149b61a342f0d4d06a08" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Dec 02 12:10:13 2009 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Thu Dec 03 11:34:26 2009 +0100" }, "message": "rcu: Rename \"quiet\" functions\n\nThe number of \"quiet\" functions has grown recently, and the\nnames are no longer very descriptive. The point of all of these\nfunctions is to do some portion of the task of reporting a\nquiescent state, so rename them accordingly:\n\no\tcpu_quiet() becomes rcu_report_qs_rdp(), which reports a\n\tquiescent state to the per-CPU rcu_data structure. If this\n\tturns out to be a new quiescent state for this grace period,\n\tthen rcu_report_qs_rnp() will be invoked to propagate the\n\tquiescent state up the rcu_node hierarchy.\n\no\tcpu_quiet_msk() becomes rcu_report_qs_rnp(), which reports\n\ta quiescent state for a given CPU (or possibly a set of CPUs)\n\tup the rcu_node hierarchy.\n\no\tcpu_quiet_msk_finish() becomes rcu_report_qs_rsp(), which\n\treports a full set of quiescent states to the global rcu_state\n\tstructure.\n\no\ttask_quiet() becomes rcu_report_unblock_qs_rnp(), which reports\n\ta quiescent state due to a task exiting an RCU read-side critical\n\tsection that had previously blocked in that same critical section.\n\tAs indicated by the new name, this type of quiescent state is\n\treported up the rcu_node hierarchy (using rcu_report_qs_rnp()\n\tto do so).\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nAcked-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\nAcked-by: Lai Jiangshan \u003claijs@cn.fujitsu.com\u003e\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12597846163698-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "b668c9cf3e58739dac54a1d6f42f2b4bdd980b3e", "tree": "c0165d39532a2314f8187d765f3c8ddf88b72831", "parents": [ "2f51f9884f6a36b0fe9636d5a1937e5cbd25723b" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Sun Nov 22 08:53:48 2009 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Sun Nov 22 18:58:15 2009 +0100" }, "message": "rcu: Fix grace-period-stall bug on large systems with CPU hotplug\n\nWhen the last CPU of a given leaf rcu_node structure goes\noffline, all of the tasks queued on that leaf rcu_node structure\n(due to having blocked in their current RCU read-side critical\nsections) are requeued onto the root rcu_node structure. This\nrequeuing is carried out by rcu_preempt_offline_tasks().\nHowever, it is possible that these queued tasks are the only\nthing preventing the leaf rcu_node structure from reporting a\nquiescent state up the rcu_node hierarchy. Unfortunately, the\nold code would fail to do this reporting, resulting in a\ngrace-period stall given the following sequence of events:\n\n1.\tKernel built for more than 32 CPUs on 32-bit systems or for more\n\tthan 64 CPUs on 64-bit systems, so that there is more than one\n\trcu_node structure. (Or CONFIG_RCU_FANOUT is artificially set\n\tto a number smaller than CONFIG_NR_CPUS.)\n\n2.\tThe kernel is built with CONFIG_TREE_PREEMPT_RCU.\n\n3.\tA task running on a CPU associated with a given leaf rcu_node\n\tstructure blocks while in an RCU read-side critical section\n\t-and- that CPU has not yet passed through a quiescent state\n\tfor the current RCU grace period. This will cause the task\n\tto be queued on the leaf rcu_node\u0027s blocked_tasks[] array, in\n\tparticular, on the element of this array corresponding to the\n\tcurrent grace period.\n\n4.\tEach of the remaining CPUs corresponding to this same leaf rcu_node\n\tstructure pass through a quiescent state. However, the task is\n\tstill in its RCU read-side critical section, so these quiescent\n\tstates cannot be reported further up the rcu_node hierarchy.\n\tNevertheless, all bits in the leaf rcu_node structure\u0027s -\u003eqsmask\n\tfield are now zero.\n\n5.\tEach of the remaining CPUs go offline. (The events in step\n\t#4 and #5 can happen in any order as long as each CPU passes\n\tthrough a quiescent state before going offline.)\n\n6.\tWhen the last CPU goes offline, __rcu_offline_cpu() will invoke\n\trcu_preempt_offline_tasks(), which will move the task to the\n\troot rcu_node structure, but without reporting a quiescent state\n\tup the rcu_node hierarchy (and this failure to report a quiescent\n\tstate is the bug).\n\n\tBut because this leaf rcu_node structure\u0027s -\u003eqsmask field is\n\talready zero and its -\u003eblock_tasks[] entries are all empty,\n\tforce_quiescent_state() will skip this rcu_node structure.\n\n\tTherefore, grace periods are now hung.\n\nThis patch abstracts some code out of rcu_read_unlock_special(),\ncalling the result task_quiet() by analogy with cpu_quiet(), and\ninvokes task_quiet() from both rcu_read_lock_special() and\n__rcu_offline_cpu(). Invoking task_quiet() from\n__rcu_offline_cpu() reports the quiescent state up the rcu_node\nhierarchy, fixing the bug. This ends up requiring a separate\nlock_class_key per level of the rcu_node hierarchy, which this\npatch also provides.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12589088301770-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "4bcfe055030d9e953945def3864f7e6997b27782", "tree": "5021112c826572bd0b356f193c2be742e54deb4f", "parents": [ "956539b75921f561c0956c22d37320780e8b4ba1" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Tue Nov 10 13:37:21 2009 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Tue Nov 10 22:48:50 2009 +0100" }, "message": "rcu: Rename dynticks_completed to completed_fqs\n\nThis field is used whether or not CONFIG_NO_HZ is set, so the\nold name of -\u003edynticks_completed is quite misleading.\n\nChange to -\u003ecompleted_fqs, given that it the value that\nforce_quiescent_state() is trying to drive the -\u003ecompleted field\naway from.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12578890423298-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "dbe01350fa8ce0c11948ab7d6be71a4d901be151", "tree": "8d79460aeb616f39f95ff74357c7b72ad3501839", "parents": [ "9160306e6f5b68bb64630c9031c517ca1cf463db" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Tue Nov 10 13:37:19 2009 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Tue Nov 10 22:48:49 2009 +0100" }, "message": "rcu: Remove inline from forward-referenced functions\n\nSome variants of gcc are reputed to dislike forward references\nto functions declared \"inline\". Remove the \"inline\" keyword\nfrom such functions.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12578890422402-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "d09b62dfa336447c52a5ec9bb88adbc479b0f3b8", "tree": "70a002fed2e0471def01ea3c166137449cb1527d", "parents": [ "281d150c5f8892f158747594ab49ce2823fd8b8c" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Mon Nov 02 13:52:28 2009 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Tue Nov 10 04:11:54 2009 +0100" }, "message": "rcu: Fix synchronization for rcu_process_gp_end() uses of -\u003ecompleted counter\n\nImpose a clear locking design on the rcu_process_gp_end()\nfunction\u0027s use of the -\u003ecompleted counter. This is done by\ncreating a -\u003ecompleted field in the rcu_node structure, which\ncan safely be accessed under the protection of that structure\u0027s\nlock. Performance and scalability are maintained by using a\nform of double-checked locking, so that rcu_process_gp_end()\nonly acquires the leaf rcu_node structure\u0027s -\u003elock if a grace\nperiod has recently ended.\n\nThis fix reduces rcutorture failure rate by at least two orders\nof magnitude under heavy stress with force_quiescent_state()\nbeing invoked artificially often. Without this fix,\nunsynchronized access to the -\u003ecompleted field can cause\nrcu_process_gp_end() to advance callbacks whose grace period has\nnot yet expired. (Bad idea!)\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nCc: \u003cstable@kernel.org\u003e # .32.x\nLKML-Reference: \u003c12571987494069-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "281d150c5f8892f158747594ab49ce2823fd8b8c", "tree": "e46ed3e84545ec33f99f58f4b7211121bbfe3755", "parents": [ "7e1a2766e67a529f62c8cfba0a47d63fc4f7fa8a" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Mon Nov 02 13:52:27 2009 -0800" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Tue Nov 10 04:11:17 2009 +0100" }, "message": "rcu: Prepare for synchronization fixes: clean up for non-NO_HZ handling of -\u003ecompleted counter\n\nImpose a clear locking design on non-NO_HZ handling of the\n-\u003ecompleted counter. This increases the distance between the\nRCU and the CPU-hotplug mechanisms.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nCc: \u003cstable@kernel.org\u003e # .32.x\nLKML-Reference: \u003c12571987491353-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "83f5b01ffbbaea6f97c9a79d21e240dbfb69f2f1", "tree": "e278471f3b9851028ef60e283ce8c73772531d82", "parents": [ "b00bc0b237055b4c45816325ee14f0bd83e6f590" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Oct 28 08:14:49 2009 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Mon Nov 02 16:06:21 2009 +0100" }, "message": "rcu: Fix long-grace-period race between forcing and initialization\n\nVery long RCU read-side critical sections (50 milliseconds or\nso) can cause a race between force_quiescent_state() and\nrcu_start_gp() as follows on kernel builds with multi-level\nrcu_node hierarchies:\n\n1.\tCPU 0 calls force_quiescent_state(), sees that there is a\n\tgrace period in progress, and acquires -\u003efsqlock.\n\n2.\tCPU 1 detects the end of the grace period, and so\n\tcpu_quiet_msk_finish() sets rsp-\u003ecompleted to rsp-\u003egpnum.\n\tThis operation is carried out under the root rnp-\u003elock,\n\tbut CPU 0 has not yet acquired that lock. Note that\n\trsp-\u003esignaled is still RCU_SAVE_DYNTICK from the last\n\tgrace period.\n\n3.\tCPU 1 calls rcu_start_gp(), but no one wants a new grace\n\tperiod, so it drops the root rnp-\u003elock and returns.\n\n4.\tCPU 0 acquires the root rnp-\u003elock and picks up rsp-\u003ecompleted\n\tand rsp-\u003esignaled, then drops rnp-\u003elock. It then enters the\n\tRCU_SAVE_DYNTICK leg of the switch statement.\n\n5.\tCPU 2 invokes call_rcu(), and now needs a new grace period.\n\tIt calls rcu_start_gp(), which acquires the root rnp-\u003elock, sets\n\trsp-\u003esignaled to RCU_GP_INIT (too bad that CPU 0 is already in\n\tthe RCU_SAVE_DYNTICK leg of the switch statement!) and starts\n\tinitializing the rcu_node hierarchy. If there are multiple\n\tlevels to the hierarchy, it will drop the root rnp-\u003elock and\n\tinitialize the lower levels of the hierarchy.\n\n6.\tCPU 0 notes that rsp-\u003ecompleted has not changed, which permits\n both CPU 2 and CPU 0 to try updating it concurrently. If CPU 0\u0027s\n\tupdate prevails, later calls to force_quiescent_state() can\n\tcount old quiescent states against the new grace period, which\n\tcan in turn result in premature ending of grace periods.\n\n\tNot good.\n\nThis patch adds an RCU_GP_IDLE state for rsp-\u003esignaled that is\nset initially at boot time and any time a grace period ends.\nThis prevents CPU 0 from getting into the workings of\nforce_quiescent_state() in step 4. Additional locking and\nchecks prevent the concurrent update of rsp-\u003esignaled in step 6.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1256742889199-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "237c80c5c8fb7ec128cf2a756b550dc41ad7eac7", "tree": "5d6b3346f2c53cd3f7471001479a8dbd741533a3", "parents": [ "019129d595caaa5bd0b41d128308da1be6a91869" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu Oct 15 09:26:14 2009 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Thu Oct 15 20:33:01 2009 +0200" }, "message": "rcu: Fix TREE_PREEMPT_RCU CPU_HOTPLUG bad-luck hang\n\nIf the following sequence of events occurs, then\nTREE_PREEMPT_RCU will hang waiting for a grace period to\ncomplete, eventually OOMing the system:\n\no\tA TREE_PREEMPT_RCU build of the kernel is booted on a system\n\twith more than 64 physical CPUs present (32 on a 32-bit system).\n\tAlternatively, a TREE_PREEMPT_RCU build of the kernel is booted\n\twith RCU_FANOUT set to a sufficiently small value that the\n\tphysical CPUs populate two or more leaf rcu_node structures.\n\no\tA task is preempted in an RCU read-side critical section\n\twhile running on a CPU corresponding to a given leaf rcu_node\n\tstructure.\n\no\tAll CPUs corresponding to this same leaf rcu_node structure\n\trecord quiescent states for the current grace period.\n\no\tAll of these same CPUs go offline (hence the need for enough\n\tphysical CPUs to populate more than one leaf rcu_node structure).\n\tThis causes the preempted task to be moved to the root rcu_node\n\tstructure.\n\nAt this point, there is nothing left to cause the quiescent\nstate to be propagated up the rcu_node tree, so the current\ngrace period never completes.\n\nThe simplest fix, especially after considering the deadlock\npossibilities, is to detect this situation when the last CPU is\nofflined, and to set that CPU\u0027s -\u003eqsmask bit in its leaf\nrcu_node structure. This will cause the next invocation of\nforce_quiescent_state() to end the grace period.\n\nWithout this fix, this hang can be triggered in an hour or so on\nsome machines with rcutorture and random CPU onlining/offlining.\nWith this fix, these same machines pass a full 10 hours of this\nsort of abuse.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c20091015162614.GA19131@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "37c72e56f6b234ea7387ba530434a80abf2658d8", "tree": "1c589c3ecdebbe19488359795cde4c55726a63aa", "parents": [ "2bc872036e1c5948b5b02942810bbdd8dbdb9812" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Oct 14 10:15:55 2009 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Thu Oct 15 11:17:16 2009 +0200" }, "message": "rcu: Prevent RCU IPI storms in presence of high call_rcu() load\n\nAs the number of callbacks on a given CPU rises, invoke\nforce_quiescent_state() only every blimit number of callbacks\n(defaults to 10,000), and even then only if no other CPU has\ninvoked force_quiescent_state() in the meantime.\n\nThis should fix the performance regression reported by Nick.\n\nReported-by: Nick Piggin \u003cnpiggin@suse.de\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nCc: jens.axboe@oracle.com\nLKML-Reference: \u003c12555405592133-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "e74f4c4564455c91a3b4075bb1721993c2a95dda", "tree": "213f9df0974c6e1e729de207b2c6dd942a39ba8c", "parents": [ "d0ec774cb2599c858be9d923bb873cf6697520d8" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Tue Oct 06 21:48:17 2009 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Wed Oct 07 08:11:20 2009 +0200" }, "message": "rcu: Make hot-unplugged CPU relinquish its own RCU callbacks\n\nThe current interaction between RCU and CPU hotplug requires that\nRCU block in CPU notifiers waiting for callbacks to drain.\n\nThis can be greatly simplified by having each CPU relinquish its\nown callbacks, and for both _rcu_barrier() and CPU_DEAD notifiers\nto adopt all callbacks that were previously relinquished.\n\nThis change also eliminates the possibility of certain types of\nhangs due to the previous practice of waiting for callbacks to be\ninvoked from within CPU notifiers. If you don\u0027t every wait, you\ncannot hang.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@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: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c1254890898456-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "a0b6c9a78c41dc36732d6e1e90f0f2f57b29816f", "tree": "4e68c76c95a74e1c8f3360c10e2c3496b7a7df0d", "parents": [ "3d76c082907e8f83c5d5c4572f38d53ad8f00c4b" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Mon Sep 28 07:46:33 2009 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Mon Oct 05 21:02:04 2009 +0200" }, "message": "rcu: Clean up code based on review feedback from Josh Triplett, part 4\n\nThese issues identified during an old-fashioned face-to-face code\nreview extending over many hours. This group improves an existing\nabstraction and introduces two new ones. It also fixes an RCU\nstall-warning bug found while making the other changes.\n\no\tMake RCU_INIT_FLAVOR() declare its own variables, removing\n\tthe need to declare them at each call site.\n\no\tCreate an rcu_for_each_leaf() macro that scans the leaf\n\tnodes of the rcu_node tree.\n\no\tCreate an rcu_for_each_node_breadth_first() macro that does\n\ta breadth-first traversal of the rcu_node tree, AKA\n\tstepping through the array in index-number order.\n\no\tIf all CPUs corresponding to a given leaf rcu_node\n\tstructure go offline, then any tasks queued on that leaf\n\twill be moved to the root rcu_node structure. Therefore,\n\tthe stall-warning code must dump out tasks queued on the\n\troot rcu_node structure as well as those queued on the leaf\n\trcu_node structures.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@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: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12541491934126-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "9b2619aff0332e95ea5eb7a0d75b0208818d871c", "tree": "a1aed182c4f1ec511352c0e3cb3eba0e20535263", "parents": [ "1eba8f84380bede3c602bd7758dea96925cead01" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Sep 23 09:50:43 2009 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Wed Sep 23 19:46:30 2009 +0200" }, "message": "rcu: Clean up code to address Ingo\u0027s checkpatch feedback\n\nMove declarations and update storage classes to make checkpatch happy.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@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: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12537246441701-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "1eba8f84380bede3c602bd7758dea96925cead01", "tree": "32dd97671016c9fdc24d75be50cc8540e6cc0730", "parents": [ "fc2219d49ef1606e7fd2c88af2b423b01ff3d319" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Sep 23 09:50:42 2009 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Wed Sep 23 19:46:29 2009 +0200" }, "message": "rcu: Clean up code based on review feedback from Josh Triplett, part 2\n\nThese issues identified during an old-fashioned face-to-face code\nreview extending over many hours.\n\no\tAdd comments for tricky parts of code, and correct comments\n\tthat have passed their sell-by date.\n\no\tGet rid of the vestiges of rcu_init_sched(), which is no\n\tlonger needed now that PREEMPT_RCU is gone.\n\no\tMove the #include of rcutree_plugin.h to the end of\n\trcutree.c, which means that, rather than having a random\n\tcollection of forward declarations, the new set of forward\n\tdeclarations document the set of plugins. The new home for\n\tthis #include also allows __rcu_init_preempt() to move into\n\trcutree_plugin.h.\n\no\tFix rcu_preempt_check_callbacks() to be static.\n\nSuggested-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\nSigned-off-by: Paul E. McKenney \u003cpaulmck@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: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12537246443924-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\nPeter Zijlstra \u003cpeterz@infradead.org\u003e\n" }, { "commit": "fc2219d49ef1606e7fd2c88af2b423b01ff3d319", "tree": "1c1cba7e4334898a98cf0e2c992e8cfef4b34979", "parents": [ "0729e196147692d84d4c099fcff056eba2ed61d8" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Wed Sep 23 09:50:41 2009 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Wed Sep 23 19:46:29 2009 +0200" }, "message": "rcu: Clean up code based on review feedback from Josh Triplett\n\nThese issues identified during an old-fashioned face-to-face code\nreview extended over many hours.\n\no\tBury various forms of the \"rsp-\u003ecompleted \u003d\u003d rsp-\u003egpnum\"\n\tcomparison into an rcu_gp_in_progress() function, which has\n\tthe beneficial side-effect of forcing consistent use of\n\tACCESS_ONCE().\n\no\tReplace hand-coded arithmetic with DIV_ROUND_UP().\n\no\tBury several \"!list_empty(\u0026rnp-\u003eblocked_tasks[rnp-\u003egpnum \u0026 0x01])\"\n\tinstances into an rcu_preempted_readers() function, as this\n\texpression indicates that there are no readers blocked\n\twithin RCU read-side critical sections blocking the current\n\tgrace period. (Though there might well be similar readers\n\tblocking the next grace period.)\n\no\tRemove a dangling rcu_restart_cpu() declaration that has\n\tbeen dangling for almost 20 minor releases of the kernel.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nAcked-by: Peter Zijlstra \u003cpeterz@infradead.org\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: akpm@linux-foundation.org\nCc: mathieu.desnoyers@polymtl.ca\nCc: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nCc: dhowells@redhat.com\nLKML-Reference: \u003c12537246442687-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "a71fca58b7f4abca551ae2256ac08dd9123a03f9", "tree": "55bef0550ff2558a117d768426474e15b081ff4b", "parents": [ "49e291266d0920264471d9d64268fb030e33a99a" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Fri Sep 18 10:28:19 2009 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Sat Sep 19 08:53:22 2009 +0200" }, "message": "rcu: Fix whitespace inconsistencies\n\nFix a number of whitespace ^Ierrors in the include/linux/rcu*\nand the kernel/rcu* files.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@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: josh@joshtriplett.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nCc: Valdis.Kletnieks@vt.edu\nLKML-Reference: \u003c20090918172819.GA24405@linux.vnet.ibm.com\u003e\n[ did more checkpatch fixlets ]\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "868489660dabc0c28087cca3dbc1adbbc398c6fe", "tree": "cf991ec94ce29bccfef27213107748810c51a1ca", "parents": [ "dd5d19bafd90d33043a4a14b2e2d98612caa293c" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Thu Aug 27 15:00:12 2009 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Sat Aug 29 15:34:40 2009 +0200" }, "message": "rcu: Changes from reviews: avoid casts, fix/add warnings, improve comments\n\nChanges suggested by review comments from Josh Triplett and\nMathieu Desnoyers.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@linux.vnet.ibm.com\u003e\nAcked-by: Josh Triplett \u003cjosh@joshtriplett.org\u003e\nAcked-by: Mathieu Desnoyers \u003cmathieu.desnoyers@polymtl.ca\u003e\nCc: laijs@cn.fujitsu.com\nCc: dipankar@in.ibm.com\nCc: akpm@linux-foundation.org\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nLKML-Reference: \u003c20090827220012.GA30525@linux.vnet.ibm.com\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "f41d911f8c49a5d65c86504c19e8204bb605c4fd", "tree": "59bcd3048652ef290b3e19d2904409afd5c90eb3", "parents": [ "a157229cabd6dd8cfa82525fc9bf730c94cc9ac2" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Sat Aug 22 13:56:52 2009 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Sun Aug 23 10:32:40 2009 +0200" }, "message": "rcu: Merge preemptable-RCU functionality into hierarchical RCU\n\nCreate a kernel/rcutree_plugin.h file that contains definitions\nfor preemptable RCU (or, under the #else branch of the #ifdef,\nempty definitions for the classic non-preemptable semantics).\nThese definitions fit into plugins defined in kernel/rcutree.c\nfor this purpose.\n\nThis variant of preemptable RCU uses a new algorithm whose\nread-side expense is roughly that of classic hierarchical RCU\nunder CONFIG_PREEMPT. This new algorithm\u0027s update-side expense\nis similar to that of classic hierarchical RCU, and, in absence\nof read-side preemption or blocking, is exactly that of classic\nhierarchical RCU. Perhaps more important, this new algorithm\nhas a much simpler implementation, saving well over 1,000 lines\nof code compared to mainline\u0027s implementation of preemptable\nRCU, which will hopefully be retired in favor of this new\nalgorithm.\n\nThe simplifications are obtained by maintaining per-task\nnesting state for running tasks, and using a simple\nlock-protected algorithm to handle accounting when tasks block\nwithin RCU read-side critical sections, making use of lessons\nlearned while creating numerous user-level RCU implementations\nover the past 18 months.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@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: josht@linux.vnet.ibm.com\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nLKML-Reference: \u003c12509746134003-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "d6714c22b43fbcbead7e7b706ff270e15f04a791", "tree": "1dc15e57d982351bed45b7b9768a118f86b88c19", "parents": [ "9f77da9f40045253e91f55c12d4481254b513d2d" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Sat Aug 22 13:56:46 2009 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Sun Aug 23 10:32:37 2009 +0200" }, "message": "rcu: Renamings to increase RCU clarity\n\nMake RCU-sched, RCU-bh, and RCU-preempt be underlying\nimplementations, with \"RCU\" defined in terms of one of the\nthree. Update the outdated rcu_qsctr_inc() names, as these\nfunctions no longer increment anything.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@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: josht@linux.vnet.ibm.com\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nLKML-Reference: \u003c12509746132696-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "9f77da9f40045253e91f55c12d4481254b513d2d", "tree": "8699c413d1493855ca8b1205e1b63090f568af42", "parents": [ "b560d8ad8583803978aaaeba50ef29dc8e97a610" ], "author": { "name": "Paul E. McKenney", "email": "paulmck@linux.vnet.ibm.com", "time": "Sat Aug 22 13:56:45 2009 -0700" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Sun Aug 23 10:32:36 2009 +0200" }, "message": "rcu: Move private definitions from include/linux/rcutree.h to kernel/rcutree.h\n\nSome information hiding that makes it easier to merge\npreemptability into rcutree without descending into #include\nhell.\n\nSigned-off-by: Paul E. McKenney \u003cpaulmck@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: josht@linux.vnet.ibm.com\nCc: dvhltc@us.ibm.com\nCc: niv@us.ibm.com\nCc: peterz@infradead.org\nCc: rostedt@goodmis.org\nLKML-Reference: \u003c1250974613373-git-send-email-\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" }, { "commit": "6258c4fb59e77d748f7efc2c137ad420372edd07", "tree": "c1e2ae0f027e81e55613b043ce44965858475d59", "parents": [ "b1f77b0581b8fd837acb4a973f7d5496cae6efee" ], "author": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Wed Mar 25 16:42:24 2009 +0100" }, "committer": { "name": "Ingo Molnar", "email": "mingo@elte.hu", "time": "Fri Apr 03 12:23:03 2009 +0200" }, "message": "kmemtrace, rcu: fix rcu_tree_trace.c data structure dependencies\n\nImpact: cleanup\n\nWe want to remove rcutree internals from the public rcutree.h file for\nupcoming kmemtrace changes - but kernel/rcutree_trace.c depends on them.\n\nIntroduce kernel/rcutree.h for internal definitions. (Probably all\nthe other data types from include/linux/rcutree.h could be\nmoved here too - except rcu_data.)\n\nCc: Pekka Enberg \u003cpenberg@cs.helsinki.fi\u003e\nCc: Eduard - Gabriel Munteanu \u003ceduard.munteanu@linux360.ro\u003e\nCc: paulmck@linux.vnet.ibm.com\nLKML-Reference: \u003c1237898630.25315.83.camel@penberg-laptop\u003e\nSigned-off-by: Ingo Molnar \u003cmingo@elte.hu\u003e\n" } ] }